Class Client (2.13.0)

This is the main class to interact with GCS. It provides member functions to invoke all the APIs in the service.

Performance

Creating an object of this type is a relatively low-cost operation. Connections to the service are created on demand. Copy-assignment and copy-construction are also relatively low-cost operations, they should be comparable to copying a few shared pointers. The first request (or any request that requires a new connection) incurs the cost of creating the connection and authenticating with the service. Note that the library may need to perform other bookkeeping operations that may impact performance. For example, access tokens need to be refreshed from time to time, and this may impact the performance of some operations.

Connection Pool

By default this class uses HTTPS to communicate with the service. Creating a new HTTPS session is relatively expensive, as it must go through the TCP/IP and SSL handshakes. To minimize this overhead the class maintains a connection pool to the service. After each request completes the connection is returned to the pool, and reused in future requests. Note that for downloads (implemented by the ReadObject() member function) the connection remains in use until the download completes. Therefore, having multiple downloads open at the same time requires multiple connections. The application can limit the maximum size of this connection pool using storage::ConnectionPoolSizeOption. If returning a connection to the pool would make the pool larger than this limit then the oldest connection in the pool is closed (recall that all connections in the pool are inactive). Note that this is the maximum size of the pool, the client library does not create connections until needed.

Note that the application may (at times) use more connections than the maximum size of the pool. For example if N downloads are in progress the library may need N connections, even if the pool size is smaller.

Two clients that compare equal share the same connection pool. Two clients created with the default constructor or with the constructor from a google::cloud::Options are never equal and do not share connection pools. Clients created via copy (or move) construction compare equal and share the connection pool.

Thread-safety

Instances of this class created via copy-construction or copy-assignment share the underlying pool of connections. Access to these copies via multiple threads is guaranteed to work. Two threads operating on the same instance of this class is not guaranteed to work.

Credentials

The default approach for creating a Client uses Google Application Default Credentials (ADCs). Note that a default-constructed client uses the ADCs:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client();
    PerformSomeOperations(client, bucket_name, object_name);
  }

Finding or loading the ADCs can fail. This will result in run-time errors when making requests.

If you prefer to explicitly load the ADCs use:

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::Options;
  using ::google::cloud::UnifiedCredentialsOption;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client(Options{}.set<UnifiedCredentialsOption>(
        google::cloud::MakeGoogleDefaultCredentials()));
    PerformSomeOperations(client, bucket_name, object_name);
  }

To load a service account credentials key file use:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Other credential types are available, including:

• google::cloud::MakeInsecureCredentials() for anonymous access to public GCS buckets or objects.
• google::cloud::MakeAccessTokenCredentials() to use an access token obtained through any out-of-band mechanism.
• google::cloud::MakeImpersonateServiceAccountCredentials() to use the IAM credentials service and [impersonate a service account].
• google::cloud::MakeServiceAccountCredentials() to use a service account key file.

Error Handling

This class uses StatusOr<T> to report errors. When an operation fails to perform its work the returned StatusOr<T> contains the error details. If the ok() member function in the StatusOr<T> returns true then it contains the expected result. Please consult the StatusOr<T> documentation for more details.

namespace gcs = google::cloud::storage;
gcs::Client client = ...;
google::cloud::StatusOr<gcs::BucketMetadata> bucket_metadata =
    client.GetBucketMetadata("my-bucket");

if (!bucket_metadata) {
  std::cerr << "Error getting metadata for my-bucket: "
            << bucket_metadata.status() << "\n";
  return;
}

// Use bucket_metadata as a smart pointer here, e.g.:
std::cout << "The generation for " << bucket_metadata->name() " is "
          << bucket_metadata->generation() << "\n";

In addition, the main page contains examples using StatusOr<T> to handle errors.

Optional Request Options

Most of the member functions in this class can receive optional request options. For example, the default when reading multi-version objects is to retrieve the latest version:

auto stream = gcs.ReadObject("my-bucket", "my-object");

Some applications may want to retrieve specific versions. In this case just provide the Generation request option:

auto stream = gcs.ReadObject(
    "my-bucket", "my-object", gcs::Generation(generation));

Each function documents the types accepted as optional request options. These parameters can be specified in any order. Specifying a request option that is not applicable to a member function results in a compile-time error.

All operations support the following common request options:

• Fields: return a partial response, which includes only the desired fields.
• QuotaUser: attribute the request to this specific label for quota purposes.
• UserProject: change the request costs (if applicable) to this GCP project.
• CustomHeader: include a custom header with the request. These are typically used for testing, though they are sometimes helpful if environments where HTTPS traffic is mediated by a proxy.
• IfMatchEtag: a pre-condition, the operation succeeds only if the resource ETag matches. Typically used in OCC loops ("change X only if its Etag is still Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
• IfNoneMatchEtag: a pre-condition, abort the operation if the resource ETag has not changed. Typically used in caching ("return the contents of X only if the Etag is different from the last value I got, which was Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
• UserIp: attribute the request to this specific IP address for quota purpose. Not recommended, prefer QuotaUser instead.

Per-operation Overrides

In addition to the request options, which are passed on to the service to modify the request, you can specify options that override the local behavior of the library. For example, you can override the local retry policy:

  namespace g = ::google::cloud;
  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name_1,
     std::string const& object_name_2) {
    auto client = gcs::Client();
    auto metadata = client.InsertObject(
        bucket_name, object_name_1,
        "The quick brown fox jumps over the lazy dog",
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    if (!metadata) throw std::move(metadata).status();

    auto is =
        client.ReadObject(bucket_name, object_name_1,
                          g::Options{}.set<gcs::RetryPolicyOption>(
                              gcs::LimitedErrorCountRetryPolicy(10).clone()));
    auto contents = std::string{std::istreambuf_iterator<char>(is.rdbuf()), {}};
    if (is.bad()) throw google::cloud::Status(is.status());

    auto os = client.WriteObject(
        bucket_name, object_name_2,
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    os << contents;
    os.Close();
    if (os.bad()) throw google::cloud::Status(os.metadata().status());

    auto result = client.DeleteObject(
        bucket_name, object_name_1, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();

    metadata = os.metadata();
    result = client.DeleteObject(
        bucket_name, object_name_2, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();
  }

Retry, Backoff, and Idempotency Policies

The library automatically retries requests that fail with transient errors, and follows the recommended practice to backoff between retries.

The default policies are to continue retrying for up to 15 minutes, and to use truncated (at 5 minutes) exponential backoff, doubling the maximum backoff period between retries. Likewise, the idempotency policy is configured to retry all operations.

The application can override these policies when constructing objects of this class. The documentation for the constructors show examples of this in action.

See Also

https://cloud.google.com/storage/ for an overview of GCS.

See Also

https://cloud.google.com/storage/docs/key-terms for an introduction of the key terms used in GCS.

See Also

https://cloud.google.com/storage/docs/json_api/ for an overview of the underlying API.

See Also

https://cloud.google.com/docs/authentication/production for details about Application Default Credentials.

See Also

google::cloud::StatusOr.

See Also

LimitedTimeRetryPolicy and LimitedErrorCountRetryPolicy for alternative retry policies.

See Also

ExponentialBackoffPolicy to configure different parameters for the exponential backoff policy.

See Also

AlwaysRetryIdempotencyPolicy and StrictIdempotencyPolicy for alternative idempotency policies.

See Also

ClientOptionList for a list of useful Client Library Configuration.

Idempotency Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only retries idempotent operations, the default is
    // to retry all operations.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::IdempotencyPolicyOption>(
            gcs::StrictIdempotencyPolicy().clone()));
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Modified Retry Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only gives up on the third error. The default policy
    // is to retry for several minutes.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(3).clone()));

    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Change Credentials Example

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& project_id) {
    int count = 0;
    for (auto&& bucket_metadata : client.ListBucketsForProject(project_id)) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in project " << project_id << "\n";
    }
  }

The default project is required to be configured in the ClientOptions used to construct this object. If the application does not set the project id in the ClientOptions, the value of the GOOGLE_CLOUD_PROJECT is used. If neither the environment variable is set, nor a value is set explicitly by the application, the returned ListBucketsReader will return an error status when used.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListBucketsReader bucket_list = client.ListBuckets();
    for (auto&& bucket_metadata : bucket_list) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in default project\n";
    }
  }

If the default project is not configured the server will reject the request, and this function returns the error status.

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucket(bucket_name, gcs::BucketMetadata());
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created."
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& project_id) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucketForProject(bucket_name, project_id,
                                      gcs::BucketMetadata{});
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created for project "
              << project_id << " [" << bucket_metadata->project_number() << "]"
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_get_bucket_metadata]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "The metadata for bucket " << bucket_metadata->name() << " is "
              << *bucket_metadata << "\n";
  }
  // [END storage_get_bucket_metadata]

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    google::cloud::Status status = client.DeleteBucket(bucket_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The bucket " << bucket_name << " was deleted successfully.\n";
  }

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a Buckets: update request to change the writable attributes in BucketMetadata.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case,IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> meta = client.GetBucketMetadata(bucket_name);
    if (!meta) throw std::move(meta).status();

    meta->set_storage_class(storage_class);
    StatusOr<gcs::BucketMetadata> updated =
        client.UpdateBucket(bucket_name, *meta);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated the storage class in " << updated->name() << " to "
              << updated->storage_class() << "."
              << "\nFull metadata:" << *updated << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request.

This function creates a patch request to change the writeable attributes in original to the values in updated. Non-writeable attributes are ignored, and attributes not present in updated are removed. Typically this function is used after the application obtained a value with GetBucketMetadata and has modified these parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    gcs::BucketMetadata desired = *original;
    desired.set_storage_class(storage_class);

    StatusOr<gcs::BucketMetadata> patched =
        client.PatchBucket(bucket_name, *original, desired);
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access?".

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a patch request based on the given BucketMetadataPatchBuilder which represents the desired set of changes.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetStorageClass(storage_class));
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to query the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies and their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();
    std::cout << "The IAM policy for bucket " << bucket_name << " is "
              << *policy << "\n";
  }

See Also

google::cloud::storage::NativeIamPolicy for details about the NativeIamPolicy class.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to set the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example: adding a new member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    for (auto& binding : policy->bindings()) {
      if (binding.role() != role || binding.has_condition()) {
        continue;
      }
      auto& members = binding.members();
      if (std::find(members.begin(), members.end(), member) == members.end()) {
        members.emplace_back(member);
      }
    }

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

Example: removing a IAM member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));
    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    std::vector<google::cloud::storage::NativeIamBinding> updated_bindings;
    for (auto& binding : policy->bindings()) {
      auto& members = binding.members();
      if (binding.role() == role && !binding.has_condition()) {
        members.erase(std::remove(members.begin(), members.end(), member),
                      members.end());
      }
      if (!members.empty()) {
        updated_bindings.emplace_back(std::move(binding));
      }
    }
    policy->bindings() = std::move(updated_bindings);

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

See Also

google::cloud::storage::NativeIamPolicy for details about the NativeIamPolicy class.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation tests the permissions of the caller for a Bucket. You must provide a list of permissions, this API will return the subset of those permissions that the current caller has in the given Bucket.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::vector<std::string> const& permissions) {
    StatusOr<std::vector<std::string>> actual_permissions =
        client.TestBucketIamPermissions(bucket_name, permissions);
    if (!actual_permissions) throw std::move(actual_permissions).status();

    if (actual_permissions->empty()) {
      std::cout << "The caller does not hold any of the tested permissions the"
                << " bucket " << bucket_name << "\n";
      return;
    }

    std::cout << "The caller is authorized for the following permissions on "
              << bucket_name << ": ";
    for (auto const& permission : *actual_permissions) {
      std::cout << "\n    " << permission;
    }
    std::cout << "\n";
  }

The Bucket Lock feature allows you to configure a data retention policy for a Cloud Storage bucket that governs how long objects in the bucket must be retained. The feature also allows you to lock the data retention policy, permanently preventing the policy from being reduced or removed.

Idempotency

This operation is always idempotent because the metageneration parameter is always required, and it acts as a pre-condition on the operation.

Example: lock the retention policy

  // [START storage_lock_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> updated_metadata =
        client.LockBucketRetentionPolicy(bucket_name,
                                         original->metageneration());
    if (!updated_metadata) throw std::move(updated_metadata).status();

    if (!updated_metadata->has_retention_policy()) {
      std::cerr << "The bucket " << updated_metadata->name()
                << " does not have a retention policy, even though the"
                << " operation to set it was successful.\n"
                << "This is unexpected, and may indicate that another"
                << " application has modified the bucket concurrently.\n";
      return;
    }

    std::cout << "Retention policy successfully locked for bucket "
              << updated_metadata->name() << "\nNew retention policy is: "
              << updated_metadata->retention_policy()
              << "\nFull metadata: " << *updated_metadata << "\n";
  }
  // [END storage_lock_retention_policy]

Example: get the current retention policy

  // [START storage_get_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    if (!bucket_metadata->has_retention_policy()) {
      std::cout << "The bucket " << bucket_metadata->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << bucket_metadata->name()
              << " retention policy is set to "
              << bucket_metadata->retention_policy() << "\n";
  }
  // [END storage_get_retention_policy]

Example: set the current retention policy

  // [START storage_set_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::chrono::seconds period) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetRetentionPolicy(period),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << "\n";
  }
  // [END storage_set_retention_policy]

Example: remove the retention policy

  // [START storage_remove_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name, gcs::BucketMetadataPatchBuilder().ResetRetentionPolicy(),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << ". This is unexpected, maybe a concurrent change by another"
              << " application?\n";
  }
  // [END storage_remove_retention_policy]

See Also

https://cloud.google.com/storage/docs/bucket-lock for a description of the Bucket Lock feature.

See Also

https://cloud.google.com/storage/docs/using-bucket-lock for examples of how to use the Bucket Lock and retention policy features.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Use CopyObject to copy between objects in the same location and storage class. Copying objects across locations or storage classes can fail for large objects and retrying the operation will not succeed.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta =
        client.CopyObject(source_bucket_name, source_object_name,
                          destination_bucket_name, destination_object_name);
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

Example: copy an encrypted object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& key_base64) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta = client.CopyObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, gcs::EncryptionKey::FromBase64Key(key_base64));
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/objects/copy for a full description of the advantages of Objects: rewrite over Objects: copy.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The metadata for object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket() << " is "
              << *object_metadata << "\n";
  }

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    for (auto&& object_metadata : client.ListObjects(bucket_name)) {
      if (!object_metadata) throw std::move(object_metadata).status();

      std::cout << "bucket_name=" << object_metadata->bucket()
                << ", object_name=" << object_metadata->name() << "\n";
    }
  }

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& bucket_prefix) {
    for (auto&& item : client.ListObjectsAndPrefixes(
             bucket_name, gcs::Prefix(bucket_prefix), gcs::Delimiter("/"))) {
      if (!item) throw std::move(item).status();
      auto result = *std::move(item);
      if (absl::holds_alternative<gcs::ObjectMetadata>(result)) {
        std::cout << "object_name="
                  << absl::get<gcs::ObjectMetadata>(result).name() << "\n";
      } else if (absl::holds_alternative<std::string>(result)) {
        std::cout << "prefix     =" << absl::get<std::string>(result) << "\n";
      }
    }
  }

Returns an object derived from std::istream which can be used to read the contents of the GCS blob. The application should check the badbit (e.g. by calling stream.bad()) on the returned object to detect if there was an error reading from the blob. If badbit is set, the application can check the status() variable to get details about the failure. Applications can also set the exception mask on the returned stream, in which case an exception is thrown if an error is detected.

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_stream_file_download]
  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      ++count;
    }

    std::cout << "The object has " << count << " lines\n";
  }
  // [END storage_stream_file_download]

Example: read only a sub-range in the object.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::int64_t start, std::int64_t end) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name, gcs::ReadRange(start, end));

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      std::cout << line << "\n";
      ++count;
    }

    std::cout << "The requested range has " << count << " lines\n";
  }

Example: read a object encrypted with a CSEK.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& base64_aes256_key) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name,
                          gcs::EncryptionKey::FromBase64Key(base64_aes256_key));

    std::string data(std::istreambuf_iterator<char>{stream}, {});
    std::cout << "The object contents are: " << data << "\n";
  }

Example: disable decompressive transcoding.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    auto is =
        client.ReadObject(bucket_name, object_name, gcs::AcceptEncodingGzip());
    auto const contents = std::string{std::istream_iterator<char>(is), {}};
    if (!is.status().ok()) throw google::cloud::Status(is.status());
    std::cout << "The object has " << contents.size() << " characters\n";
  }

This creates a std::ostream object to upload contents. The application can use either the regular operator<<(), or std::ostream::write() to upload data.

This function always uses resumable uploads. The application can provide a #RestoreResumableUploadSession() option to resume a previously created upload. The returned object has accessors to query the session id and the next byte expected by GCS.

For small uploads we recommend using InsertObject, consult the documentation for details.

If the application does not provide a #RestoreResumableUploadSession() option, or it provides the #NewResumableUploadSession() option then a new resumable upload session is created.

More information about buffering and recommendations around performance in the ObjectWriteStream class documentation.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, int desired_line_count) {
    std::string const text = "Lorem ipsum dolor sit amet";
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name);

    for (int lineno = 0; lineno != desired_line_count; ++lineno) {
      // Add 1 to the counter, because it is conventional to number lines
      // starting at 1.
      stream << (lineno + 1) << ": " << text << "\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: write an object with a CMEK.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& kms_key_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::KmsKeyName(kms_key_name));

    // Line numbers start at 1.
    for (int lineno = 1; lineno <= 10; ++lineno) {
      stream << lineno << ": placeholder text for CMEK example.\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: starting a resumable upload.

  namespace gcs = ::google::cloud::storage;
  return [](gcs::Client client, std::string const& bucket_name,
            std::string const& object_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::NewResumableUploadSession(),
        gcs::AutoFinalizeDisabled());
    auto session_id = stream.resumable_session_id();
    std::cout << "Created resumable upload: " << session_id << "\n";
    // Because this stream was created with `AutoFinalizeDisabled()` its
    // destructor will *not* finalize the upload, allowing a separate process or
    // function to resume and continue the upload.
    stream << "This data will not get uploaded, it is too small\n";
    return session_id;
  }

Example: resuming a resumable upload.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& session_id) {
    // Restore a resumable upload stream, the library automatically queries the
    // state of the upload and discovers the next expected byte.
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name,
                           gcs::RestoreResumableUploadSession(session_id));
    if (!stream.IsOpen() && stream.metadata().ok()) {
      std::cout << "The upload has already been finalized.  The object "
                << "metadata is: " << *stream.metadata() << "\n";
    }
    if (stream.next_expected_byte() == 0) {
      // In this example we create a small object, smaller than the resumable
      // upload quantum (256 KiB), so either all the data is there or not.
      // Applications use `next_expected_byte()` to find the position in their
      // input where they need to start uploading.
      stream << R"""(
Lorem ipsum dolor sit amet, consectetur adipiscing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim
ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit
esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat
non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
)""";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = stream.metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Upload completed, the new object metadata is: " << *metadata
              << "\n";
  }

See Also

Resumable Uploads for more information about resumable uploads.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: manually selecting a resumable upload

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0),
        gcs::NewResumableUploadSession());
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Idempotency

This operation is always idempotent because it only acts on a specific upload_session_url.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& file_name) {
    google::cloud::Status status =
        client.DownloadToFile(bucket_name, object_name, file_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Downloaded " << object_name << " to " << file_name << "\n";
  }

Idempotency

This operation is only idempotent if:

• restricted by pre-conditions, in this case, IfGenerationMatch
• or, if it applies to only one object version via Generation.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    google::cloud::Status status =
        client.DeleteObject(bucket_name, object_name);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted " << object_name << " in bucket " << bucket_name
              << "\n";
  }

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key,
     std::string const& value) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    gcs::ObjectMetadata desired = *object_metadata;
    desired.mutable_metadata().emplace(key, value);

    StatusOr<gcs::ObjectMetadata> updated =
        client.UpdateObject(bucket_name, object_name, desired,
                            gcs::Generation(object_metadata->generation()));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

This function creates a patch request to change the writeable attributes in original to the values in updated. Non-writeable attributes are ignored, and attributes not present in updated are removed. Typically this function is used after the application obtained a value with GetObjectMetadata and has modified these parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key) {
    StatusOr<gcs::ObjectMetadata> original =
        client.GetObjectMetadata(bucket_name, object_name);

    if (!original) throw std::move(original).status();
    gcs::ObjectMetadata desired = *original;
    desired.mutable_metadata().erase(key);

    StatusOr<gcs::ObjectMetadata> updated =
        client.PatchObject(bucket_name, object_name, *original, desired);

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

This function creates a patch request based on the given builder. Typically this function is used when the application needs to set an object's metadata fields regardless of their previous value (i.e. when calling GetObjectMetadata first is not necessary).

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type) {
    StatusOr<gcs::ObjectMetadata> updated = client.PatchObject(
        bucket_name, object_name,
        gcs::ObjectMetadataPatchBuilder().SetContentType(content_type));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name);
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Example: using encrypted objects with CSEK

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::string const& base64_aes256_key,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name,
        gcs::EncryptionKey::FromBase64Key(base64_aes256_key));
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation returns a ObjectRewriter, which the application can use to initiate the copy and to iterate if the copy requires more than one call to complete.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    gcs::ObjectRewriter rewriter =
        client.RewriteObject(source_bucket_name, source_object_name,
                             destination_bucket_name, destination_object_name);

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Applications use this function to resume a rewrite operation, possibly created with RewriteObject(). Rewrite can reliably copy objects across location boundaries, and can rewrite objects with different encryption keys. For large objects this operation can take a long time, thus applications should consider checkpointing the rewrite token (accessible in the ObjectRewriter) and restarting the operation in the event the program is terminated.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation blocks until the rewrite completes, and returns the resulting ObjectMetadata.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name);
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << destination_object_name
              << " Metadata: " << *metadata << "\n";
  }

Example: using rewrite object to rotate the encryption key

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& old_key_base64,
     std::string const& new_key_base64) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.RewriteObjectBlocking(
            bucket_name, object_name, bucket_name, object_name,
            gcs::SourceEncryptionKey::FromBase64Key(old_key_base64),
            gcs::EncryptionKey::FromBase64Key(new_key_base64));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "Rotated key on object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket()
              << "\nFull Metadata: " << *object_metadata << "\n";
  }

Example: using rewrite object to rename an object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& old_object_name, std::string const& new_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        bucket_name, old_object_name, bucket_name, new_object_name);
    if (!metadata) throw std::move(metadata).status();

    google::cloud::Status status =
        client.DeleteObject(bucket_name, old_object_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Renamed " << old_object_name << " to " << new_object_name
              << " in bucket " << bucket_name << "\n";
  }

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::BucketAccessControl>> items =
        client.ListBucketAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::BucketAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> bucket_acl =
        client.CreateBucketAcl(bucket_name, entity, role);

    if (!bucket_acl) throw std::move(bucket_acl).status();
    std::cout << "Role " << bucket_acl->role() << " granted to "
              << bucket_acl->entity() << " on bucket " << bucket_acl->bucket()
              << "\n"
              << "Full attributes: " << *bucket_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status = client.DeleteBucketAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::BucketAccessControl> acl =
        client.GetBucketAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in bucket "
              << acl->bucket() << " is " << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    gcs::BucketAccessControl desired_acl =
        gcs::BucketAccessControl().set_entity(entity).set_role(role);

    StatusOr<gcs::BucketAccessControl> updated_acl =
        client.UpdateBucketAcl(bucket_name, desired_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "Bucket ACL updated. The ACL entry for "
              << updated_acl->entity() << " in bucket " << updated_acl->bucket()
              << " is " << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Computes the delta between a previous value for an BucketAccessControl and the new value for an BucketAccessControl and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> original_acl =
        client.GetBucketAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::BucketAccessControl> patched_acl =
        client.PatchBucketAcl(bucket_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

This API allows the application to patch an BucketAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> patched_acl = client.PatchBucketAcl(
        bucket_name, entity,
        gcs::BucketAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListObjectAcl(bucket_name, object_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for object=" << object_name << " in bucket "
              << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> object_acl =
        client.CreateObjectAcl(bucket_name, object_name, entity, role);

    if (!object_acl) throw std::move(object_acl).status();
    std::cout << "Role " << object_acl->role() << " granted to "
              << object_acl->entity() << " on " << object_acl->object()
              << "\nFull attributes: " << *object_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    google::cloud::Status status =
        client.DeleteObjectAcl(bucket_name, object_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in object "
              << object_name << " in bucket " << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in object "
              << acl->object() << " in bucket " << acl->bucket() << " is "
              << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> current_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!current_acl) throw std::move(current_acl).status();
    current_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateObjectAcl(bucket_name, object_name, *current_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "ACL entry for " << updated_acl->entity() << " in object "
              << updated_acl->object() << " in bucket " << updated_acl->bucket()
              << " is now " << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

Compute the delta between a previous value for an ObjectAccessControl and the new value for an ObjectAccessControl and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    gcs::ObjectAccessControl new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity,
        gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListDefaultObjectAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> default_object_acl =
        client.CreateDefaultObjectAcl(bucket_name, entity, role);
    if (!default_object_acl) throw std::move(default_object_acl).status();

    std::cout << "Role " << default_object_acl->role()
              << " will be granted default to " << default_object_acl->entity()
              << " on any new object created on bucket "
              << default_object_acl->bucket() << "\n"
              << "Full attributes: " << *default_object_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status =
        client.DeleteDefaultObjectAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetDefaultObjectAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "Default Object ACL entry for " << acl->entity()
              << " in bucket " << acl->bucket() << " is " << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    original_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateDefaultObjectAcl(bucket_name, *original_acl);
    if (!updated_acl) throw std::move(updated_acl).status();

    std::cout << "Default Object ACL entry for " << updated_acl->entity()
              << " in bucket " << updated_acl->bucket() << " is now "
              << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Compute the delta between a previous and new values for a default object access control, and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(bucket_name, entity, *original_acl,
                                     new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(
            bucket_name, entity,
            gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

A service account is a special Google account that belongs to your application, virtual machine, or to a Google service when acting on your behalf. This API allows you to discover the GCS service account for the project_id project.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& project_id) {
    StatusOr<gcs::ServiceAccount> account =
        client.GetServiceAccountForProject(project_id);
    if (!account) throw std::move(account).status();

    std::cout << "The service account details for project " << project_id
              << " are " << *account << "\n";
  }

See Also

https://cloud.google.com/iam/docs/service-accounts for general information on Google Cloud Platform service accounts.

A service account is a special Google account that belongs to your application, virtual machine, or to a Google service when acting on your behalf. This API allows you to discover the GCS service account for the default project associated with this object.

The default project is required to be configured in the ClientOptions used to construct this object. If the application does not set the project id in the ClientOptions, the value of the GOOGLE_CLOUD_PROJECT is used. If neither the environment variable is set, nor a value is set explicitly by the application, the server will reject the request and this function will return the error status.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    StatusOr<gcs::ServiceAccount> account = client.GetServiceAccount();
    if (!account) throw std::move(account).status();

    std::cout << "The service account details are " << *account << "\n";
  }

See Also

https://cloud.google.com/iam/docs/service-accounts for general information on Google Cloud Platform service accounts.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list = client.ListHmacKeys();
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys in default project\n";
    }
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& service_account) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list =
        client.ListHmacKeys(gcs::ServiceAccountFilter(service_account));
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys for service account " << service_account
                << " in default project\n";
    }
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Idempotency

This operation is not idempotent. Retrying the operation will create a new key each time.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> key_info =
        client.CreateHmacKey(service_account_email);
    if (!key_info) throw std::move(key_info).status();

    std::cout << "The base64 encoded secret is: " << key_info->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << key_info->first << "\n";
    return key_info->first.access_id();
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& project_id,
            std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> hmac_key_details =
        client.CreateHmacKey(service_account_email,
                             gcs::OverrideDefaultProject(project_id));
    if (!hmac_key_details) throw std::move(hmac_key_details).status();

    std::cout << "The base64 encoded secret is: " << hmac_key_details->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << hmac_key_details->first
              << "\n";
    return hmac_key_details->first.access_id();
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Idempotency

This operation is always idempotent. An access id identifies a single HMAC key, calling the operation multiple times can succeed only once.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& access_id) {
    google::cloud::Status status = client.DeleteHmacKey(access_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The key is deleted, though it may still appear"
              << " in ListHmacKeys() results.\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Idempotency

This is a read-only operation and therefore it is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id) {
    StatusOr<gcs::HmacKeyMetadata> hmac_key = client.GetHmacKey(access_id);
    if (!hmac_key) throw std::move(hmac_key).status();

    std::cout << "The HMAC key metadata is: " << *hmac_key << "\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Idempotency

This operation is only idempotent if the etag attribute in resource is set, or if the IfMatchEtag option is set.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id,
     std::string const& state) {
    StatusOr<gcs::HmacKeyMetadata> updated = client.UpdateHmacKey(
        access_id, gcs::HmacKeyMetadata().set_state(std::move(state)));
    if (!updated) throw std::move(updated).status();

    std::cout << "The updated HMAC key metadata is: " << *updated << "\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Helper Functions

The following functions create a AddSubResourceOption with less opportunities for typos in the sub-resource name: WithAcl(), WithBilling(), WithCompose(), WithCors(), WithEncryption(), WithEncryptionConfig(), WithLifecycle(), WithLocation(), WithLogging(), WithStorageClass(), and WithTagging().

Likewise, the following helper functions can create properly formatted AddExtensionHeaderOption objects: WithGeneration(), WithGenerationMarker(), WithMarker(), WithResponseContentDisposition(), WithResponseContentType(), and WithUserProject().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "GET", std::move(bucket_name), std::move(object_name),
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "PUT", std::move(bucket_name), std::move(object_name),
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::ContentType("application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/signed-urls for a general description of signed URLs and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Helper Functions

The following functions create a AddSubResourceOption with less opportunities for typos in the sub-resource name: WithAcl(), WithBilling(), WithCompose(), WithCors(), WithEncryption(), WithEncryptionConfig(), WithLifecycle(), WithLocation(), WithLogging(), WithStorageClass(), and WithTagging().

Likewise, the following helper functions can create properly formatted AddExtensionHeaderOption objects: WithGeneration(), WithGenerationMarker(), WithMarker(), WithResponseContentDisposition(), WithResponseContentType(), and WithUserProject().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "GET", std::move(bucket_name), std::move(object_name),
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "PUT", std::move(bucket_name), std::move(object_name),
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::AddExtensionHeader("content-type", "application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/signed-urls for a general description of signed URLs and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::NotificationMetadata>> items =
        client.ListNotifications(bucket_name);
    if (!items) throw std::move(items).status();

    std::cout << "Notifications for bucket=" << bucket_name << "\n";
    for (gcs::NotificationMetadata const& notification : *items) {
      std::cout << notification << "\n";
    }
  }

Cloud Pub/Sub Notifications send information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Cloud Pub/Sub Notifications send information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options. This function fetches the detailed information for a given notification config.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.GetNotification(bucket_name, notification_id);
    if (!notification) throw std::move(notification).status();

    std::cout << "Notification " << notification->id() << " for bucket "
              << bucket_name << "\n";
    if (notification->object_name_prefix().empty()) {
      std::cout << "This notification is sent for all objects in the bucket\n";
    } else {
      std::cout << "This notification is sent only for objects starting with"
                << " the prefix " << notification->object_name_prefix() << "\n";
    }
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options. This function deletes one of the notification configs.

Idempotency

This operation is always idempotent because it only acts on a specific notification_id, the state after calling this function multiple times is to delete that notification. New notifications get different ids.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    google::cloud::Status status =
        client.DeleteNotification(bucket_name, notification_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Successfully deleted notification " << notification_id
              << " on bucket " << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentResult> document =
        client.CreateSignedPolicyDocument(
            gcs::PolicyDocument{
                std::chrono::system_clock::now() + std::chrono::minutes(15),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "bucket", std::move(bucket_name)),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

See Also

https://cloud.google.com/storage/docs/xml-api/post-object#policydocument for a general description of policy documents and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentV4Result> document =
        client.GenerateSignedPostPolicyV4(
            gcs::PolicyDocumentV4{
                std::move(bucket_name),
                "scan_0001.jpg",
                std::chrono::minutes(15),
                std::chrono::system_clock::now(),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

See Also

https://cloud.google.com/storage/docs/xml-api/post-object#policydocument for a general description of policy documents and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.