Access persistent storage

This page explains how to create and manage persistent storage for container workloads in your Google Distributed Cloud (GDC) air-gapped sovereign universe. Persistent storage provides your application with consistent identities and stable hostnames, regardless of where its workloads are scheduled.

This page is for developers within the application operator group, who are responsible for creating application workloads for their organization. For more information, see Audiences for GDC air-gapped documentation.

Before you begin

To run commands against a Kubernetes cluster, make sure you have the following resources:

  1. Locate the Kubernetes cluster name, or ask your Platform Administrator what the cluster name is.

  2. Sign in and generate the kubeconfig file for the Kubernetes cluster if you don't have one.

  3. Use the kubeconfig path of the Kubernetes cluster to replace KUBERNETES_CLUSTER_KUBECONFIG in these instructions.

To get the required permissions to create a persistent volume, ask your Organization IAM Admin to grant you the Namespace Admin role (namespace-admin) in your project namespace.

Create a persistent volume

The following instructions show how to create a volume using the GDC standard-rwo StorageClass. For more information on the available StorageClass resources in GDC, see Persistent storage for containers.

  1. Create a PersistentVolumeClaim and configure it with a ReadWriteOnce access mode and a standard-rwo storage class:

    kubectl --kubeconfig KUBERNETES_CLUSTER_KUBECONFIG \
    --namespace NAMESPACE 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_KUBECONFIG: the kubeconfig file for the cluster.

    • NAMESPACE: the project namespace in which to create the PVC.

    • PVC_NAME: the name of the PersistentVolumeClaim object.

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

    kubectl get pv --kubeconfig KUBERNETES_CLUSTER_KUBECONFIG

    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

  3. Configure your container workloads to use the PVC. The following is an example nginx pod that uses a standard-rwo PVC:

    kubectl --kubeconfig KUBERNETES_CLUSTER_KUBECONFIG \
    --namespace NAMESPACE apply -f - <<EOF
apiVersion: apps/v1
kind: Pod
metadata:
  name: web-server-deployment
  labels:
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
    - mountPath: /usr/share/nginx/html
      name: data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: PVC_NAME
EOF

    Replace PVC_NAME with the PVC you created.

Expand volume capacity

To increase the capacity of a PersistentVolumeClaim object, update the spec.resources.storage field to the new capacity. The maximum supported volume size is 14.5 Ti.

  1. Update the volume to a larger size in the manifest file of the PersistentVolumeClaim object:

    kubectl --kubeconfig KUBERNETES_CLUSTER_KUBECONFIG \
    --namespace NAMESPACE apply -f - <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: PVC_NAME
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: VOLUME_STORAGE_SIZE
EOF

    Replace the following:

    • KUBERNETES_CLUSTER_KUBECONFIG: the kubeconfig file for the cluster.

    • NAMESPACE: the project namespace in which the PVC resource exists.

    • PVC_NAME: the name of the PVC for which you are increasing the storage size.

    • VOLUME_SNAPSHOT_SIZE: the storage size amount to increase, such as 50Gi.

  2. Check the status of the updated PVs in your cluster:

    kubectl get pv --kubeconfig KUBERNETES_CLUSTER_KUBECONFIG

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