Deploy a high availability container application
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Deploy a container application across multiple zones and configure asynchronous storage replication to build a robust, highly available (HA) service in Google Distributed Cloud (GDC) air-gapped. An HA container application uses Kubernetes orchestration for automated pod scheduling, rescheduling, and service discovery across zones.

You must complete the following high-level steps to make your container application highly available:

Create a Kubernetes cluster in two or more zones in your GDC universe.
Configure global load balancing.
Deploy container workloads to each zonal Kubernetes cluster.
Expose your container workloads to the network.
Provision storage and attach it to your pods.
Configure asynchronous storage replication, using either block storage or object storage.

Before you begin

Ensure you are working in a GDC universe with multiple zones available. Run gdcloud zones list to list the zones available in your universe. For more information, see List zones in a universe.
Ask your Organization IAM Admin to grant you the following roles:
- The Namespace Admin (namespace-admin) role to create and manage container workloads.
- The User Cluster Admin (user-cluster-admin) and User Cluster Developer (user-cluster-developer) roles to create and manage Kubernetes clusters and their node pools.
- The Load Balancer Admin (load-balancer-admin) and the Global Load Balancer Admin (global-load-balancer-admin) roles. You must have these role to create and manage load balancers.
- The Volume Replication Global Admin role (app-volume-replication-admin-global). You must have this role to administer volume replication.
- The Global PNP Admin (global-project-networkpolicy-admin) role to create and manage project network policies across zones.
- The Harbor Instance Admin (harbor-instance-admin), Harbor Instance Viewer(harbor-instance-viewer), and Harbor Project Creator (harbor-project-creator) roles. These roles are required to create and manage container images in the artifact registry.
- The Volume Replication Global Admin (app-volume-replication-admin-global) role to administer the volume replication relationship for block storage resources.
- The Project Bucket Object Admin (project-bucket-object-admin) and Project Bucket Admin (project-bucket-admin) roles to create and manage storage buckets.
See role descriptions for more information.
Install and configure the gdcloud CLI, and configure your zonal and global contexts. See Manage resources across zones for more information.
Install and configure the kubectl CLI, with appropriate kubeconfig files set for the global API server, Management API server, and Kubernetes cluster. See Manually generate kubeconfig file for more information.

Deploy a container application with HA

Complete the following steps to deploy a container application across zones with replicated storage for the application state.

Create a Kubernetes cluster in multiple zones

A Kubernetes cluster is a zonal resource, so you must create a cluster separately in each zone.

Console

In the navigation menu, select Kubernetes Engine > Clusters.

Important: Notice you cannot select a project in the scope picker while creating a Kubernetes cluster. This is because the cluster is organization-scoped. For more details, see the resource hierarchy.
Click Create Cluster.
In the Name field, specify a name for the cluster.
Select the Kubernetes version for the cluster.
Select the zone in which to create the cluster.
Click Attach Project and select an existing project to attach to your cluster. Then click Save. You can attach or detach projects after creating the cluster from the Project details page. You must have a project attached to your cluster before deploying container workloads it.
Click Next.
Configure the network settings for your cluster. You can't change these network settings after you create the cluster. The default and only supported Internet Protocol for Kubernetes clusters is Internet Protocol version 4 (IPv4).
1. Specify the Load Balancer IP address pool size, such as 20.
2. Select the Service CIDR (Classless Inter-Domain Routing) to use. Your deployed services, such as load balancers, are allocated IP addresses from this range.
  
  Important: The range can be any RFC 1918 range that doesn't conflict with other IP address ranges in the cluster and node pool resources. See RFC 1918 for more information, but note that you must connect to the internet to access the URL. This URL provides access outside of your air-gapped environment.
3. Select the pod CIDR to use. The cluster allocates IP addresses from this range to your pods and VMs.
4. Click Next.
Review the details of the auto-generated default node pool for the cluster. Click Edit to modify the default node pool.

Important: If you intend the cluster to run graphics processing unit (GPU) workloads, you must provision a GPU machine type in your cluster. For more information, see Cluster node machine types.
To create additional node pools, select Add node pool. When editing the default node pool or adding a new node pool, you customize it with the following options:
1. Assign a name for the node pool. You cannot modify the name after you create the node pool.
2. Specify the number of worker nodes to create in the node pool.
3. Select your machine class that best suits your workload requirements. View the list of the following settings:
  - Machine type
  - CPU
  - Memory
4. Click Save.
5. Click Create to create the cluster.
Repeat these steps for each zone in your GDC universe. Make sure a Kubernetes cluster resides in every zone that you want for your HA strategy.

API

To create a new Kubernetes cluster using the API directly, apply a custom resource to each GDC zone.

Create a Cluster custom resource and deploy it to the Management API server for your zone:
```
kubectl --kubeconfig MANAGEMENT_API_SERVER apply -f - <<EOF \
apiVersion: cluster.gdc.goog/v1
kind: Cluster
metadata:
  name: CLUSTER_NAME
  namespace: platform
spec:
  clusterNetwork:
    podCIDRSize: POD_CIDR
    serviceCIDRSize: SERVICE_CIDR
  initialVersion:
    kubernetesVersion: KUBERNETES_VERSION
  loadBalancer:
    ingressServiceIPSize: LOAD_BALANCER_POOL_SIZE
  nodePools:
  - machineTypeName: MACHINE_TYPE
    name: NODE_POOL_NAME
    nodeCount: NUMBER_OF_WORKER_NODES
    taints: TAINTS
    labels: LABELS
    acceleratorOptions:
      gpuPartitionScheme: GPU_PARTITION_SCHEME
  releaseChannel:
    channel: UNSPECIFIED
EOF
```
Replace the following:
- MANAGEMENT_API_SERVER: the kubeconfig path of the zonal Management API server. For more information, see Switch to the zonal context.
- CLUSTER_NAME: the name of the cluster. The cluster name must not end with -system. The -system suffix is reserved for clusters created by GDC.
- POD_CIDR: the size of network ranges from which pod virtual IP addresses (VIP) are allocated. If unset, the default value 21 is used.
- SERVICE_CIDR: the size of network ranges from which service VIPs are allocated. If unset, the default value 23 is used.
- KUBERNETES_VERSION: the Kubernetes version of the cluster, such as 1.26.5-gke.2100. To list the available Kubernetes versions to configure, see List available Kubernetes versions for a cluster.
- LOAD_BALANCER_POOL_SIZE: the size of non-overlapping IP address pools used by load balancer services. If unset, the default value 20 is used.
- MACHINE_TYPE: the machine type for the worker nodes of the node pool. View the available machine types for what is available to configure.
- NODE_POOL_NAME: the name of the node pool.
- NUMBER_OF_WORKER_NODES: the number of worker nodes to provision in the node pool.
- TAINTS: the taints to apply to the nodes of this node pool. This is an optional field.
- LABELS: the labels to apply to the nodes of this node pool. It contains a list of key-value pairs. This is an optional field.
- GPU_PARTITION_SCHEME: the GPU partitioning scheme, if you're running GPU workloads, such as mixed-2. The GPU is not partitioned if this field is not set. For available Multi-Instance GPU (MIG) profiles, see Supported MIG profiles.
Note: You cannot edit node configurations, such as GPU partitioning, after a cluster node pool is created.
Repeat the previous step for each zone that you want hosting your container application for your HA strategy.

Configure load balancers

To distribute traffic between your pods in different zones, create load balancers. You have the option to create external load balancers (ELB) and internal load balancers (ILB), both of which can be configured zonally or globally. For this example, configure a global ILB and global ELB for your container application.

Create a global internal load balancer

Internal load balancers (ILB) expose services within the organization from an internal IP address pool assigned to the organization. An ILB service is never accessible from any endpoint outside of the organization.

Complete the following steps to create a global ILB for your container workloads.

gdcloud

Create an ILB that targets pod workloads using the gdcloud CLI.

This ILB targets all of the workloads in the project matching the label defined in the Backend object. The Backend custom resource must be scoped to a zone.

To create an ILB using the gdcloud CLI, follow these steps:

Create a zonal Backend resource in each zone where your pods are running to define the endpoint for the ILB:
```
gdcloud compute backends create BACKEND_NAME \
    --labels=LABELS \
    --project=PROJECT \
    --cluster=CLUSTER_NAME \
    --zone=ZONE
```
Replace the following:
- BACKEND_NAME: the chosen name for the backend resource, such as my-backend.
- LABELS: the selector defining which endpoints between pods to use for this backend resource, such as app=web.
- PROJECT: the name of your project.
- CLUSTER_NAME: the Kubernetes cluster to which the scope of the defined selectors is limited to. If this field is not specified, all of the endpoints with the given label are selected. This field is optional.
- ZONE: the zone to use for this invocation. To preset the zone flag for all commands that require it, run gdcloud config set core/zone ZONE. The zone flag is available only in multi-zone environments. This field is optional.
Repeat this step for each zone in your GDC universe.
Create a global BackendService resource:
```
gdcloud compute backend-services create BACKEND_SERVICE_NAME \
    --project=PROJECT \
    --target-ports=TARGET_PORTS \
    --global
```
Replace the following:
- BACKEND_SERVICE_NAME: the name for the backend service.
- PROJECT: the name of your project.
- TARGET_PORTS: a comma-separated list of target ports that this backend service translates, where each target port specifies the protocol, the port on the forwarding rule, and the port on the backend instance. You can specify multiple target ports. This field must be in the format protocol:port:targetport, such as TCP:80:8080. This field is optional.
Add the BackendService resource to the previously created Backend resource in each zone:
```
gdcloud compute backend-services add-backend BACKEND_SERVICE_NAME \
    --backend-zone=ZONE \
    --backend=BACKEND_NAME \
    --project=PROJECT \
    --global
```
Replace the following:
- BACKEND_SERVICE_NAME: the name of the global backend service.
- ZONE: the zone of the backend.
- BACKEND_NAME: the name of the zonal backend.
- PROJECT: the name of your project.
Complete this step for each zonal backend you created previously.
Create an internal ForwardingRule resource that defines the virtual IP address (VIP) the service is available at:
```
gdcloud compute forwarding-rules create FORWARDING_RULE_INTERNAL_NAME \
    --backend-service=BACKEND_SERVICE_NAME \
    --cidr=CIDR \
    --ip-protocol-port=PROTOCOL_PORT \
    --load-balancing-scheme=INTERNAL \
    --project=PROJECT \
    --global
```
Replace the following:
- FORWARDING_RULE_INTERNAL_NAME: the name for the forwarding rule.
- CIDR: the CIDR to use for your forwarding rule. This field is optional. If not specified, an IPv4/32 CIDR is automatically reserved from the global IP address pool. Specify the name of a Subnet resource in the same namespace as this forwarding rule. A Subnet resource represents the request and allocation information of a global subnet. For more information on Subnet resources, see Manage subnets.
- PROTOCOL_PORT: the protocol and port to expose on the forwarding rule. This field must be in the format ip-protocol=TCP:80. The exposed port must be the same as what the actual application is exposing inside of the container.
To validate the configured ILB, confirm the Ready condition on each of the created objects. Verify the traffic with a curl request to the VIP:
1. To get the assigned VIP, describe the forwarding rule:
```
gdcloud compute forwarding-rules describe FORWARDING_RULE_INTERNAL_NAME --global
```
2. Verify the traffic with a curl request to the VIP at the port specified in the field in the forwarding rule:
```
curl http://FORWARDING_RULE_VIP:PORT
```
Replace the following:
- FORWARDING_RULE_VIP: the VIP of the forwarding rule.
- PORT: the port number of the forwarding rule.

API

Create an ILB that targets container workloads using the KRM API. This ILB targets all of the workloads in the project matching the label defined in the Backend object. To create a global ILB using the KRM API, follow these steps:

Create a Backend resource to define the endpoints for the ILB. Create Backend resources for each zone the container workloads are placed in:
```
kubectl --kubeconfig MANAGEMENT_API_SERVER apply -f - <<EOF
apiVersion: networking.gdc.goog/v1
kind: Backend
metadata:
  namespace: PROJECT
  name: BACKEND_NAME
spec:
  clusterName: CLUSTER_NAME
  endpointsLabels:
    matchLabels:
      app: APP_NAME
EOF
```
Replace the following:
- MANAGEMENT_API_SERVER: the kubeconfig path of the zonal Management API server's kubeconfig path. For more information, see Switch to a zonal context.
- PROJECT: the name of your project.
- BACKEND_NAME: the name of the Backend resource.
- CLUSTER_NAME: the Kubernetes cluster to which the scope of the defined selectors is limited to. If this field is not specified, all of the endpoints with the given label are selected. This field is optional.
- APP_NAME: the name of your container application.
You can use the same Backend resource for each zone, or create Backend resources with different label sets for each zone.
Create a BackendService object using the previously created Backend resource. Make sure to include the HealthCheck resource:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: BackendService
metadata:
  namespace: PROJECT
  name: BACKEND_SERVICE_NAME
spec:
  backendRefs:
  - name: BACKEND_NAME
    zone: ZONE
  healthCheckName: HEALTH_CHECK_NAME
  targetPorts:
  - port: PORT
    protocol: PROTOCOL
    targetPort: TARGET_PORT
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig path of the global API server's kubeconfig path.
- PROJECT: the name of your project.
- BACKEND_SERVICE_NAME: the chosen name for your BackendService resource.
- HEALTH_CHECK_NAME: the name of your previously created HealthCheck resource.
- BACKEND_NAME: the name of the zonal Backend resource.
- ZONE: the zone in which the Backend resource resides. You can specify multiple backends in the backendRefs field. For example:
```
- name: my-backend-1
  zone: us-east1-a
- name: my-backend-2
  zone: us-east1-b
```
  The targetPorts field is optional. This resource lists ports that this BackendService resource translates. If you are using this object, provide values for the following:
- PORT: the port exposed by the service.
- PROTOCOL: the Layer-4 protocol which traffic must match. Only TCP and UDP are supported.
- TARGET_PORT: the port to which the value is translated to, such as 8080. The value can't be repeated in a given object.
  
  An example for targetPorts might look like the following:
```
targetPorts:
  - port: 80
    protocol: TCP
    targetPort: 8080
```
Create an internal ForwardingRule resource defining the virtual IP address (VIP) the service is available at.
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ForwardingRuleInternal
metadata:
  namespace: PROJECT
  name: FORWARDING_RULE_INTERNAL_NAME
spec:
  cidrRef: CIDR
  ports:
  - port: PORT
    protocol: PROTOCOL
  backendServiceRef:
    name: BACKEND_SERVICE_NAME
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig path of the global API server's kubeconfig path.
- PROJECT: the name of your project.
- FORWARDING_RULE_INTERNAL_NAME: the chosen name for your ForwardingRuleInternal resource.
- CIDR: the CIDR to use for your forwarding rule. This field is optional. If not specified, an IPv4/32 CIDR is automatically reserved from the global IP address pool. Specify the name of a Subnet resource in the same namespace as this forwarding rule. A Subnet resource represents the request and allocation information of a global subnet. For more information on Subnet resources, see Manage subnets.
- PORT: the port to expose on the forwarding rule. Use the ports field to specify an array of L4 ports for which packets are forwarded to the backends configured with this forwarding rule. At least one port must be specified. Use the port field to specify a port number. The exposed port must be the same as what the actual application is exposing inside of the container.
- PROTOCOL: the protocol to use for the forwarding rule, such as TCP. An entry in the ports array must look like the following:
```
ports:
- port: 80
  protocol: TCP
```
To validate the configured ILB, confirm the Ready condition on each of the created objects. Verify the traffic with a curl request to the VIP:
1. Retrieve the VIP:
```
kubectl get forwardingruleinternal -n PROJECT
```
  The output looks like the following:
```
NAME           BACKENDSERVICE                  CIDR              READY
ilb-name       BACKEND_SERVICE_NAME            192.0.2.0/32      True
```
2. Test the traffic with a curl request to the VIP at the port specified in the field in the forwarding rule:
```
curl http://FORWARDING_RULE_VIP:PORT
```
  Replace the following:
  - FORWARDING_RULE_VIP: the VIP of the forwarding rule.
  - PORT: the port number of the field in the forwarding rule.

Create a global external load balancer

External load balancers (ELB) expose services to access from outside the organization from a pool's IP addresses assigned to the organization from the larger instance-external IP address pool.

Complete the following steps to create a global ELB for your container workloads.

gdcloud

Use the gdcloud CLI to create a global ELB that targets all of the workloads in the project matching the label defined in the Backend object. The Backend custom resource must be scoped to a zone.

For ELB services to function, you must configure and apply your own customized ProjectNetworkPolicy data transfer in policy to allow traffic to the workloads of this ELB service. Network policies control access to your workloads, not the load balancer itself. ELBs expose workloads to your customer network, requiring explicit network policies to allow external traffic to the workload port, such as 8080.

Specify the external CIDR address to allow traffic to the workloads of this ELB:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ProjectNetworkPolicy
metadata:
  namespace: PROJECT
  name: allow-inbound-traffic-from-external
spec:
  policyType: Ingress
  subject:
    subjectType: UserWorkload
  ingress:
  - from:
    - ipBlock:
        cidr: CIDR
    ports:
    - protocol: TCP
      port: PORT
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig path of the global API server's kubeconfig path. If you have not yet generated a kubeconfig file for the global API server, see Manually generate kubeconfig file for details.
- PROJECT: the name of your project.
- CIDR: the external CIDR that the ELB needs to be accessed from. This policy is required as the external load balancer uses Direct Server Return (DSR), which preserves the source external IP address and bypasses the load balancer on the return path. For more information, see Create a global ingress firewall rule for cross-organization traffic.
- PORT: the backend port on the pods behind the load balancer. This value is found in the .spec.ports[].targetPortfield field of the manifest for the Service resource. This field is optional.
This configuration provides all of the resources inside of projects access to the specified CIDR range.

Note: The gdcloud CLI does not support a command for creating a global project network policy, so you must use the KRM API instead.
Create a Backend resource in each zone to define the endpoint for the ELB:
```
gdcloud compute backends create BACKEND_NAME \
  --labels=LABELS \
  --project=PROJECT \
  --cluster=CLUSTER_NAME \
  --zone=ZONE
```
Replace the following:
- BACKEND_NAME: the name for the backend resource, such as my-backend.
- LABELS: a selector defining which endpoints between pods to use for this backend resource, such as app=web.
- PROJECT: the name of your project.
- CLUSTER_NAME: the Kubernetes cluster to which the scope of the defined selectors is limited to. If this field is not specified, all of the endpoints with the given label are selected. This field is optional.
- ZONE: the zone to use for this invocation. To preset the zone flag for all commands that require it, run gdcloud config set core/zone ZONE. The zone flag is available only in multi-zone environments. This field is optional.
You can use the same Backend resource for each zone, or create Backend resources with different label sets for each zone.
Create a global BackendService resource:
```
gdcloud compute backend-services create BACKEND_SERVICE_NAME \
  --project=PROJECT \
  --target-ports=TARGET_PORTS \
  --health-check=HEALTH_CHECK_NAME \
  --global
```
Replace the following:
- BACKEND_SERVICE_NAME: the chosen name for this backend service.
- PROJECT: the name of your project.
- TARGET_PORTS: a comma-separated list of target ports that this backend service translates, where each target port specifies the protocol, the port on the forwarding rule, and the port on the backend instance. You can specify multiple target ports. This field must be in the format protocol:port:targetport, such as TCP:80:8080. This field is optional.
- HEALTH_CHECK_NAME: the name of the health check resource. This field is optional.

Add the global BackendService resource to the previously created zonal Backend resource:

gdcloud compute backend-services add-backend BACKEND_SERVICE_NAME \
  --backend=BACKEND_NAME \
  --backend-zone=ZONE \
  --project=PROJECT \
  --global

Complete this step for each zonal backend you created previously.

Create an external ForwardingRule resource that defines the VIP the service is available at:
```
gdcloud compute forwarding-rules create FORWARDING_RULE_EXTERNAL_NAME \
  --backend-service=BACKEND_SERVICE_NAME \
  --cidr=CIDR \
  --ip-protocol-port=PROTOCOL_PORT \
  --load-balancing-scheme=EXTERNAL \
  --project=PROJECT \
  --global
```
Replace the following:
- FORWARDING_RULE_EXTERNAL_NAME: the name for the forwarding rule.
- CIDR: the CIDR to use for your forwarding rule. This field is optional. If not specified, an IPv4/32 CIDR is automatically reserved from the global IP address pool. Specify the name of a Subnet resource in the same namespace as this forwarding rule. A Subnet resource represents the request and allocation information of a global subnet. For more information on Subnet resources, see Manage subnets.
- PROTOCOL_PORT: the protocol and port to expose on the forwarding rule. This field must be in the format ip-protocol=TCP:80. The exposed port must be the same as what the actual application is exposing inside of the container.
- PROJECT: the name of your project.
To validate the configured ELB, confirm the Ready condition on each of the created objects. Verify the traffic with a curl request to the VIP:
1. To get the assigned VIP, describe the forwarding rule:
```
gdcloud compute forwarding-rules describe FORWARDING_RULE_EXTERNAL_NAME
```
2. Verify the traffic with a curl request to the VIP at the port specified in the PROTOCOL_PORT field in the forwarding rule:
```
curl http://FORWARDING_RULE_VIP:PORT
```
  Replace the following:
  - FORWARDING_RULE_VIP: the VIP of the forwarding rule.
  - PORT: the port number from the PROTOCOL_PORT field in the forwarding rule.

API

Create an ELB that targets pod workloads using the KRM API. This ELB targets all of the workloads in the project matching the label defined in the Backend object. To create a zonal ELB using the KRM API, follow these steps:

For ELB services to function, you must configure and apply your own customized ProjectNetworkPolicy data transfer in policy to allow traffic to the workloads of this ELB service. Network policies control access to your workloads, not the load balancer itself. ELBs expose workloads to your customer network, requiring explicit network policies to allow external traffic to the workload port, such as 8080.

Specify the external CIDR address to allow traffic to the workloads of this ELB:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ProjectNetworkPolicy
metadata:
  namespace: PROJECT
  name: allow-inbound-traffic-from-external
spec:
  policyType: Ingress
  subject:
    subjectType: UserWorkload
  ingress:
  - from:
    - ipBlock:
        cidr: CIDR
    ports:
    - protocol: TCP
      port: PORT
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig path of the global API server's kubeconfig path. If you have not yet generated a kubeconfig file for the global API server, see Manually generate kubeconfig file for details.
- PROJECT: the name of your project.
- CIDR: the external CIDR that the ELB needs to be accessed from. This policy is required as the external load balancer uses Direct Server Return (DSR), which preserves the source external IP address and bypasses the load balancer on the return path. For more information, see Create a global ingress firewall rule for cross-organization traffic.
- PORT: the backend port on the pods behind the load balancer. This value is found in the .spec.ports[].targetPortfield field of the manifest for the Service resource. This field is optional.
Note: This configuration provides all of the resources inside of projects access to the specified CIDR range.
Create a Backend resource to define the endpoints for the ELB. Create Backend resources for each zone the workloads are placed in:
```
kubectl --kubeconfig MANAGEMENT_API_SERVER apply -f - <<EOF
apiVersion: networking.gdc.goog/v1
kind: Backend
metadata:
  namespace: PROJECT
  name: BACKEND_NAME
spec:
  clusterName: CLUSTER_NAME
  endpointsLabels:
    matchLabels:
      app: APP_NAME
EOF
```
Replace the following:
- MANAGEMENT_API_SERVER: the kubeconfig path of the zonal Management API server's kubeconfig path. If you have not yet generated a kubeconfig file for the API server in your targeted zone, see Manually generate kubeconfig file for details.
- PROJECT: the name of your project.
- BACKEND_NAME: the name of the Backend resource.
- CLUSTER_NAME: the Kubernetes cluster to which the scope of the defined selectors is limited to. If this field is not specified, all of the endpoints with the given label are selected. This field is optional.
- APP_NAME: the name of your container application.
You can use the same Backend resource for each zone, or create Backend resources with different label sets for each zone.
Create a BackendService object using the previously created Backend resource:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: BackendService
metadata:
  namespace: PROJECT
  name: BACKEND_SERVICE_NAME
spec:
  backendRefs:
  - name: BACKEND_NAME
    zone: ZONE
  healthCheckName: HEALTH_CHECK_NAME
EOF
```
Replace the following:
- BACKEND_SERVICE_NAME: the chosen name for your BackendService resource.
- HEALTH_CHECK_NAME: the name of your previously created HealthCheck resource. Don't include this field if you are configuring an ELB for pod workloads.
- ZONE: the zone in which the Backend resource resides. You can specify multiple backends in backendRefs field. For example:
```
- name: my-backend-1
  zone: us-east1-a
- name: my-backend-2
  zone: us-east1-b
```
Create an external ForwardingRule resource defining the VIP the service is available at.
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ForwardingRuleExternal
metadata:
  namespace: PROJECT
  name: FORWARDING_RULE_EXTERNAL_NAME
spec:
  cidrRef: CIDR
  ports:
  - port: PORT
    protocol: PROTOCOL
  backendServiceRef:
    name: BACKEND_SERVICE_NAME
EOF
```
Replace the following:
- FORWARDING_RULE_EXTERNAL_NAME: the chosen name for your ForwardingRuleExternal resource.
- CIDR: the CIDR to use for your forwarding rule. This field is optional. If not specified, an IPv4/32 CIDR is automatically reserved from the global IP address pool. Specify the name of a Subnet resource in the same namespace as this forwarding rule. A Subnet resource represents the request and allocation information of a global subnet. For more information on Subnet resources, see Manage subnets.
- PORT: the port to expose on the forwarding rule. Use the ports field to specify an array of L4 ports for which packets are forwarded to the backends configured with this forwarding rule. At least one port must be specified. Use the port field to specify a port number. The exposed port must be the same as what the actual application is exposing inside of the container.
- PROTOCOL: the protocol to use for the forwarding rule, such as TCP. An entry in the ports array must look like the following:
```
ports:
- port: 80
  protocol: TCP
```
To validate the configured ELB, confirm the Ready condition on each of the created objects. Try and test the traffic with a curl request to the VIP.
1. Retrieve the VIP for the project:
```
kubectl get forwardingruleexternal -n PROJECT
```
  The output looks like the following:
```
NAME           BACKENDSERVICE                  CIDR              READY
elb-name       BACKEND_SERVICE_NAME            192.0.2.0/32      True
```
2. Verify the traffic with a curl request to the VIP at the port specified in the PORT field in the forwarding rule:
```
curl http://FORWARDING_RULE_VIP:PORT
```
  Replace FORWARDING_RULE_VIP:PORT with the VIP and port of the forwarding rule, such as 192.0.2.0:80.

Deploy container workloads to each zonal cluster

Container workloads are not a global resource, which means you must deploy each of your container applications separately into the zonal Kubernetes clusters.

Sign in to the zone that hosts your Kubernetes cluster:
```
gdcloud config set core/zone ZONE
```
Ensure your container image is available from the managed Harbor registry. For more information, see the Deploy a container app tutorial.
Create a manifest file for your container workload and deploy it to your zonal Kubernetes cluster:
```
kubectl --kubeconfig KUBERNETES_CLUSTER -n PROJECT \
    apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: DEPLOYMENT_NAME
spec:
  replicas: NUMBER_OF_REPLICAS
  selector:
    matchLabels:
      run: APP_NAME
  template:
    metadata:
      labels:
        run: APP_NAME
    spec:
      containers:
      - name: CONTAINER_NAME
        image: HARBOR_INSTANCE_URL/HARBOR_PROJECT_NAME/IMAGE:TAG
EOF
```
Replace the following:
- KUBERNETES_CLUSTER: the kubeconfig file for the zonal Kubernetes cluster to which you are deploying container workloads. If you have not yet generated a kubeconfig file for your zonal Kubernetes cluster, see Manually generate kubeconfig file for details.
- PROJECT: the project namespace in which to deploy the container workloads.
- DEPLOYMENT_NAME: the name of your container deployment.
- NUMBER_OF_REPLICAS: the number of replicated Pod objects that the deployment manages.
- APP_NAME: the name of the application to run within the deployment.
- CONTAINER_NAME: the name of the container.
- HARBOR_INSTANCE_URL: the URL of the Harbor instance, such as harbor-1.org-1.zone1.google.gdc.test. To retrieve the URL of the Harbor instance, see View Harbor registry instances.
- HARBOR_PROJECT_NAME: the name of the Harbor project, such as my-project.
- IMAGE: the image's name, such as nginx.
- TAG: the tag for the image version that you want to pull, such as 1.0.
Repeat the previous steps for each zone in your GDC universe. Make sure your container application resides in every zone that you want for your HA strategy.

Expose your container application using Kubernetes

You must expose your container application to allow access to it from other resources in your GDC universe.

Create a Service resource of type: LoadBalancer. This resource exposes your application's pods over a network.
```
kubectl --kubeconfig KUBERNETES_CLUSTER -n PROJECT \
apiVersion: v1
kind: Service
metadata:
  name: SERVICE_NAME
spec:
  selector:
    app: APP_NAME
  ports:
    - port: 80
      protocol: TCP
  type: LoadBalancer
EOF
```
Replace the following:
- KUBERNETES_CLUSTER: the kubeconfig file for the zonal Kubernetes cluster to which you are deploying container workloads.
- PROJECT: the project namespace in which your container workloads reside.
- SERVICE_NAME: the name of the load balancer service.
- APP_NAME: the label you applied for your container application.

Create a NetworkPolicy custom resource to allow all network traffic to the default namespace:

kubectl --kubeconfig KUBERNETES_CLUSTER -n PROJECT \
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  annotations:
  name: allow-all
spec:
  ingress:
  - from:
    - ipBlock:
        cidr: 0.0.0.0/0
  podSelector: {}
  policyTypes:
  - Ingress
EOF

Provision persistent storage for your pods

You must create a PersistentVolumeClaim resource (PVC) to supply application pods with persistent storage.

The following instructions show how to create a volume using the GDC standard-rwo StorageClass.

Create a PersistentVolumeClaim resource. For example, configure it with a ReadWriteOnce access mode and a standard-rwo storage class:
```
kubectl --kubeconfig KUBERNETES_CLUSTER \
    --namespace PROJECT apply -f - <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: PVC_NAME
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: standard-rwo
EOF
```
Replace the following:
- KUBERNETES_CLUSTER: the kubeconfig file for the Kubernetes cluster.
- PROJECT: the project namespace in which to create the PVC.
- PVC_NAME: the name of the PersistentVolumeClaim object.

The PersistentVolume (PV) objects are dynamically provisioned. Check the status of the new PVs in your Kubernetes cluster:

kubectl get pv --kubeconfig KUBERNETES_CLUSTER

The output is similar to the following:

NAME       CAPACITY   ACCESS MODES   STATUS      CLAIM     STORAGECLASS   AGE
pvc-uuidd  10Gi       RWO            Bound       pvc-name  standard-rwo   60s

Configure your container workloads to use the PVC. The following is an example pod manifest that uses a standard-rwo PVC:
```
kubectl --kubeconfig KUBERNETES_CLUSTER \
    --namespace PROJECT apply -f - <<EOF
apiVersion: apps/v1
kind: Pod
metadata:
  name: web-server-deployment
  labels:
    app: APP_LABEL
spec:
  containers:
  - name: CONTAINER_NAME
    image: HARBOR_INSTANCE_URL/HARBOR_PROJECT_NAME/IMAGE:TAG
    volumeMounts:
    - mountPath: MOUNT_PATH
      name: data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: PVC_NAME
EOF
```
Replace the following:
- KUBERNETES_CLUSTER: the kubeconfig file for the Kubernetes cluster to which you're deploying container workloads.
- PROJECT: the project namespace in which the PVC resides.
- APP_LABEL: the label you applied for your container application.
- CONTAINER_NAME: the name of the container.
- HARBOR_INSTANCE_URL: the URL of the Harbor instance, such as harbor-1.org-1.zone1.google.gdc.test. To retrieve the URL of the Harbor instance, see View Harbor registry instances.
- HARBOR_PROJECT_NAME: the name of the Harbor project, such as my-project.
- IMAGE: the image's name, such as nginx.
- TAG: the tag for the image version that you want to pull, such as 1.0.
- MOUNT_PATH: the path inside the pod to mount your volume.
- PVC_NAME: the PVC you created.

Configure asynchronous storage replication

GDC multi-zone universes offer the use of replicated storage resources such as volumes and buckets in asynchronous mode for disaster recovery scenarios. These storage resource options provide asynchronous data replication between any two zones in the same region. Asynchronous replication occurs in the background, providing a low, but non-zero, recovery point objective (RPO) in the event of a disaster. All replicated data is online and immediately accessible, but might require a manual failover procedure to enable writing on the secondary zone.

You can choose one of the following asynchronous storage replication types for your container application:

Asynchronous object replication
Asynchronous block replication

Create a dual-zone bucket for object storage

Object storage data is written to a single bucket whose data is stored in both zones. Because the data is copied asynchronously across zones, the zones might not contain the same object versions at any moment in time, but will eventually become equivalent if no additional changes are made. Unlike volume replication, replicated buckets are writable during zone partitions. Each write to an object produces a different version, and the latest version across either zone will be the final state after connectivity is restored.

Ensure your Infrastructure Operator (IO) has created the BucketLocationConfig custom resource, which is required for asynchronous replication across zones for object storage. This resource must be deployed to the root global API server.
Create the dual-zone Bucket custom resource:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: object.global.gdc.goog/v1
kind: Bucket
metadata:
  name: BUCKET_NAME
  namespace: PROJECT
spec:
  location: LOCATION_NAME
  description: Sample DZ Bucket
  storageClass: Standard
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig file for the global API server.
- BUCKET_NAME: the name of the storage bucket.
- PROJECT: the name of the project where the bucket resides.
- LOCATION_NAME: the physical place where object data in the bucket resides. This must map to the name of an existing BucketLocation resource. To query the global API server of your organization for a list of available BucketLocation resources, run kubectl --kubeconfig GLOBAL_API_SERVER bucketlocations. If there are no BucketLocation resources, reach out to your IO to ensure that they have enabled asynchronous replication.

Configure asynchronous block storage replication across zones

Replicated block storage provides asynchronously replicated volumes (PVs), which maintain block equivalence between the primary and secondary volumes. Due to the asynchronous nature, the secondary volume reflects the state of the primary zone at some point in the past (non-zero RPO). The secondary volume is not mountable while it remains the target of replication, requiring manual intervention to terminate the relationship and enable writes to occur.

You must configure a storage replication relationship across zones to create replicated data that is available for failover if the source zone data becomes unavailable. This is relevant if you are using block storage for your container application.

Before beginning, ensure your Infrastructure Operator (IO) has created and configured the StorageClusterPeering and StorageVirtualMachinePeering custom resources to allow for block storage replication across zones. This resource must be deployed to the root global API server.

Create a VolumeReplicationRelationship custom resource YAML file and deploy it to the global API server:
```
kubectl --kubeconfig GLOBAL_API_SERVER apply -f - <<EOF
apiVersion: storage.global.gdc.goog/v1
kind: VolumeReplicationRelationship
metadata:
  name: PVC_REPL_NAME
  namespace: PROJECT
spec:
  source:
    pvc:
      clusterRef: SOURCE_PVC_CLUSTER
      pvcRef: SOURCE_PVC
    zoneRef: SOURCE_ZONE
destination:
    pvc:
      clusterRef: DEST_PVC_CLUSTER
    zoneRef: DEST_ZONE
EOF
```
Replace the following:
- GLOBAL_API_SERVER: the kubeconfig file for the global API server.
- PVC_REPL_NAME: the name of the volume replication relationship.
- PROJECT: the project where the storage infrastructure resides.
- SOURCE_PVC_CLUSTER: the Kubernetes cluster where the PVC is hosted.
- SOURCE_PVC: the PVC in the source zone to replicate.
- SOURCE_ZONE: the source zone where the PVC is hosted.
- DEST_PVC_CLUSTER: the destination Kubernetes cluster to replicate the PVC to.
- DEST_ZONE: the destination zone to replicate the PVC to.
Create a VolumeFailover custom resource in the destination zone, which stops replication to the destination zone if the source zone is unavailable for any reason:
```
kubectl --kubeconfig MANAGEMENT_API_SERVER apply -f - <<EOF
apiVersion: storage.gdc.goog/v1
kind: VolumeFailover
metadata:
  name: PVC_FAILOVER_NAME
  namespace: PROJECT
spec:
  volumeReplicationRelationshipRef: PVC_REPL_NAME
EOF
```
Replace the following:
- MANAGEMENT_API_SERVER: the kubeconfig file of the zonal Management API server.
- PVC_FAILOVER_NAME: the name of the PVC failover.
- PROJECT: the project where the storage infrastructure resides.
- PVC_REPL_NAME: the name of the volume replication relationship.

Deploy a high availability container application Stay organized with collections Save and categorize content based on your preferences.

Before you begin

Deploy a container application with HA

Create a Kubernetes cluster in multiple zones

Console

API

Configure load balancers

Create a global internal load balancer

gdcloud

API

Create a global external load balancer

gdcloud

API

Deploy container workloads to each zonal cluster

Expose your container application using Kubernetes

Provision persistent storage for your pods

Configure asynchronous storage replication

Create a dual-zone bucket for object storage

Configure asynchronous block storage replication across zones

Deploy a high availability container application
Stay organized with collections Save and categorize content based on your preferences.