Download a public object without credentials

Download an object from a public data set object.

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For detailed documentation that includes this code sample, see the following:

Code sample

C++

For more information, see the Cloud Storage C++ API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

namespace gcs = ::google::cloud::storage;
[](std::string const& bucket_name, std::string const& object_name) {
  // Create a client that does not authenticate with the server.
  auto client = gcs::Client{
      google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
          google::cloud::MakeInsecureCredentials())};

  // Read an object, the object must have been made public.
  gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

  int count = 0;
  std::string line;
  while (std::getline(stream, line, '\n')) {
    ++count;
  }
  if (stream.bad()) throw google::cloud::Status(stream.status());
  std::cout << "The object has " << count << " lines\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.


using Google.Cloud.Storage.V1;
using System;
using System.IO;

public class DownloadPublicFileSample
{
    public string DownloadPublicFile(
        string bucketName = "your-bucket-name",
        string objectName = "your-object-name",
        string localPath = "path/to/download/object/to")
    {
        var storage = StorageClient.CreateUnauthenticated();

        using var outputFile = File.OpenWrite(localPath);
        storage.DownloadObject(bucketName, objectName, outputFile);

        Console.WriteLine($"Downloaded public file {objectName} from bucket {bucketName} to {localPath}.");
        return localPath;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"time"

	"cloud.google.com/go/storage"
	"google.golang.org/api/option"
)

// downloadPublicFile downloads a public object.
func downloadPublicFile(w io.Writer, bucket, object string) ([]byte, error) {
	// bucket := "bucket-name"
	// object := "object-name"
	ctx := context.Background()
	// Create a client that does not authenticate with the server.
	client, err := storage.NewClient(ctx, option.WithoutAuthentication())
	if err != nil {
		return nil, fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*50)
	defer cancel()

	rc, err := client.Bucket(bucket).Object(object).NewReader(ctx)
	if err != nil {
		return nil, fmt.Errorf("Object(%q).NewReader: %w", object, err)
	}
	defer rc.Close()

	data, err := ioutil.ReadAll(rc)
	if err != nil {
		return nil, fmt.Errorf("ioutil.ReadAll: %w", err)
	}
	fmt.Fprintf(w, "Blob %v downloaded.\n", object)
	return data, nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.


import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.nio.file.Path;

public class DownloadPublicObject {
  public static void downloadPublicObject(
      String bucketName, String publicObjectName, Path destFilePath) {
    // The name of the bucket to access
    // String bucketName = "my-bucket";

    // The name of the remote public file to download
    // String publicObjectName = "publicfile.txt";

    // The path to which the file should be downloaded
    // Path destFilePath = Paths.get("/local/path/to/file.txt");

    // Instantiate an anonymous Google Cloud Storage client, which can only access public files
    Storage storage = StorageOptions.getUnauthenticatedInstance().getService();

    Blob blob = storage.get(BlobId.of(bucketName, publicObjectName));
    blob.downloadTo(destFilePath);

    System.out.println(
        "Downloaded public object "
            + publicObjectName
            + " from bucket name "
            + bucketName
            + " to "
            + destFilePath);
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const srcFilename = 'your-file-name';

// The path to which the file should be downloaded
// const destFileName = '/local/path/to/file.txt';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function downloadPublicFile() {
  const options = {
    destination: destFileName,
  };

  // Download public file.
  await storage.bucket(bucketName).file(srcFileName).download(options);

  console.log(
    `Downloaded public file ${srcFileName} from bucket name ${bucketName} to ${destFileName}`
  );
}

downloadPublicFile().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

use Google\Cloud\Storage\StorageClient;

/**
 * Download a public file using anonymous credentials.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 * @param string $destination The local destination to save the object.
 *        (e.g. '/home/admin/downloads/my-object')
 */
function download_public_file(string $bucketName, string $objectName, string $destination): void
{
    // create a storage client without authentication
    $storage = new StorageClient([
    ]);

    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);

    // set `shouldSignRequest` to false to force the client to not authenticate.
    // if you do not have any client configuration enabled (i.e. application
    // default credentials), that option can be omitted.
    $object->downloadToFile($destination, [
        'shouldSignRequest' => false,
    ]);

    printf(
        'Downloaded public object %s from bucket %s to %s',
        $objectName,
        $bucketName,
        $destination
    );
}

Python

For more information, see the Cloud Storage Python API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

from google.cloud import storage


def download_public_file(bucket_name, source_blob_name, destination_file_name):
    """Downloads a public blob from the bucket."""
    # bucket_name = "your-bucket-name"
    # source_blob_name = "storage-object-name"
    # destination_file_name = "local/path/to/file"

    storage_client = storage.Client.create_anonymous_client()

    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(source_blob_name)
    blob.download_to_filename(destination_file_name)

    print(
        "Downloaded public blob {} from bucket {} to {}.".format(
            source_blob_name, bucket.name, destination_file_name
        )
    )

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

def download_public_file bucket_name:, file_name:, local_file_path:
  # The name of the bucket to access
  # bucket_name = "my-bucket"

  # The name of the remote public file to download
  # file_name = "publicfile.txt"

  # The path to which the file should be downloaded
  # local_file_path = "/local/path/to/file.txt"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.anonymous
  bucket  = storage.bucket bucket_name, skip_lookup: true
  file    = bucket.file file_name

  file.download local_file_path

  puts "Downloaded public object #{file.name} from bucket #{bucket} to #{local_file_path}"
end

What's next

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