Write new Task: Configuring a Pod to use a PersistentVolume.
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- docs/tasks/configure-pod-container/define-command-argument-container.md
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- docs/tasks/configure-pod-container/assign-cpu-ram-container.md
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- docs/tasks/configure-pod-container/configure-volume-storage.md
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- docs/tasks/configure-pod-container/configure-persistent-volume-storage.md
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- docs/tasks/configure-pod-container/distribute-credentials-secure.md
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- docs/tasks/configure-pod-container/pull-image-private-registry.md
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- docs/tasks/configure-pod-container/configure-liveness-readiness-probes.md
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---
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redirect_from:
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- "/docs/user-guide/persistent-volumes/walkthrough/"
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- "/docs/user-guide/persistent-volumes/walkthrough.html"
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title: Configuring a Pod to Use a PersistentVolume for Storage
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---
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{% capture overview %}
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This page shows how to configure a Pod to use a PersistentVolumeClaim for storage.
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Here is a summary of the process:
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1. A cluster administrator creates a PersistentVolume that is backed by physical
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storage. The administrator does not associate the volume with any Pod.
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1. A cluster user creates a PersistentVolumeClaim, which gets automatically
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bound to a suitable PersistentVolume.
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1. The user creates a Pod that uses the PersistentVolumeClaim as storage.
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{% endcapture %}
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{% capture prerequisites %}
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* You need to have a Kubernetes cluster that has only one Node, and the kubectl
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command-line tool must be configured to communicate with your cluster. If you
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do not already have a single-node cluster, you can create one by using
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[Minikube](/docs/getting-started-guides/minikube).
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* Familiarize yourself with the material in
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[Persistent Volumes](/docs/user-guide/persistent-volumes/).
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{% endcapture %}
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{% capture steps %}
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## Creating an index.html file on your Node
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Open a shell to the Node in your cluster. How you open a shell depends on how
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you set up your cluster. For example, if you are using Minikube, you can open a
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shell to your Node by entering `minikube ssh`.
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In your shell, create a `/tmp/data` directory:
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mkdir /tmp/data
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In the `/tmp/data` directory, create an `index.html` file:
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echo 'Hello from Kubernetes storage' > /tmp/data/index.html
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## Creating a PersistentVolume
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In this exercise, you create a *hostPath* PersistentVolume. Kubernetes supports
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hostPath for development and testing on a single-node cluster. A hostPath
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PersistentVolume uses a file or directory on the Node to emulate network-attached storage.
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In a production cluster, you would not use hostPath. Instead a cluster administrator
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would provision a network resource like a Google Compute Engine persistent disk,
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an NFS share, or an Amazon Elastic Block Store volume. Cluster administrators can also
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use [StorageClasses](/docs/resources-reference/v1.5/#storageclass-v1beta1)
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to set up
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[dynamic provisioning](http://blog.kubernetes.io/2016/10/dynamic-provisioning-and-storage-in-kubernetes.html).
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Here is the configuration file for the hostPath PersistentVolume:
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{% include code.html language="yaml" file="task-pv-volume.yaml" ghlink="/docs/tasks/configure-pod-container/task-pv-volume.yaml" %}
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The configuration file specifies that the volume is at `/tmp/data` on the
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the cluster's Node. The configuration also specifies a size of 10 gibibytes and
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an access mode of `ReadWriteOnce`, which means the volume can be mounted as
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read-write by a single Node.
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Create the PersistentVolume:
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kubectl create -f http://k8s.io/docs/tasks/configure-pod-container/task-pv-volume.yaml
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View information about the PersistentVolume:
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kubectl get pv task-pv-volume
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The output shows that the PersistentVolume has a `STATUS` of `Available`. This
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means it has not yet been bound to a PersistentVolumeClaim.
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NAME CAPACITY ACCESSMODES RECLAIMPOLICY STATUS CLAIM REASON AGE
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task-pv-volume 10Gi RWO Retain Available 17s
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## Creating a PersistentVolumeClaim
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The next step is to create a PersistentVolumeClaim. Pods use PersistentVolumeClaims
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to request physical storage. In this exercise, you create a PersistentVolumeClaim
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that requests a volume of at least three gibibytes that can provide read-write
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access for at least one Node.
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Here is the configuration file for the PersistentVolumeClaim:
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{% include code.html language="yaml" file="task-pv-claim.yaml" ghlink="/docs/tasks/configure-pod-container/task-pv-claim.yaml" %}
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Create the PersistentVolumeClaim:
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kubectl create -f http://k8s.io/docs/tasks/configure-pod-container/task-pv-claim.yaml
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After you create the PersistentVolumeClaim, the Kubernetes control plane looks
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for a PersistentVolume that satisfies the claim's requirements. If the control
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plane finds a suitable PersistentVolume, it binds the claim to the volume.
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Look again at the PersistentVolume:
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kubectl get pv task-pv-volume
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Now the output shows a `STATUS` of `Bound`.
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kubectl get pv task-pv-volume
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NAME CAPACITY ACCESSMODES RECLAIMPOLICY STATUS CLAIM REASON AGE
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task-pv-volume 10Gi RWO Retain Bound default/task-pv-claim 8m
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Look at the PersistentVolumeClaim:
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kubectl get pvc task-pv-claim
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The output shows that the PersistentVolumeClaim is bound to your PersistentVolume,
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`task-pv-volume`.
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NAME STATUS VOLUME CAPACITY ACCESSMODES AGE
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task-pv-claim Bound task-pv-volume 10Gi RWO 5s
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## Creating a Pod
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The next step is to create a Pod that uses your PersistentVolumeClaim as a volume.
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Here is the configuration file for the Pod:
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{% include code.html language="yaml" file="task-pv-pod.yaml" ghlink="/docs/tasks/configure-pod-container/task-pv-pod.yaml" %}
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Notice that the Pod's configuration file specifies a PersistentVolumeClaim, but
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it does not specify a PersistentVolume. From the Pod's point of view, the claim
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is a volume.
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Create the Pod:
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kubectl create -f http://k8s.io/docs/tasks/configure-pod-container/task-pv-pod.yaml
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Verify that the Container in the Pod is running;
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kubectl get pod task-pv-pod
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Get a shell to the Container running in your Pod:
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kubectl exec -it task-pv-pod -- /bin/bash
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In your shell, verify that nginx is serving the `index.html` file from the
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hostPath volume:
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root@task-pv-pod:/# apt-get update
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root@task-pv-pod:/# apt-get install curl
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root@task-pv-pod:/# curl localhost
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The output shows the text that you wrote to the `index.html` file on the
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hostPath volume:
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Hello from Kubernetes storage
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{% endcapture %}
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{% capture discussion %}
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## Access control
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Storage configured with a group ID (GID) allows writing only by Pods using the same
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GID. Mismatched or missing GIDs cause permission denied errors. To reduce the
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need for coordination with users, an administrator can annotate a PersistentVolume
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with a GID. Then the GID is automatically added to any Pod that uses the
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PersistentVolume.
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Use the `pv.beta.kubernetes.io/gid` annotation as follows:
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kind: PersistentVolume
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apiVersion: v1
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metadata:
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name: pv1
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annotations:
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pv.beta.kubernetes.io/gid: "1234"
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When a Pod consumes a PersistentVolume that has a GID annotation, the annotated GID
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is applied to all Containers in the Pod in the same way that GIDs specified in the
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Pod’s security context are. Every GID, whether it originates from a PersistentVolume
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annotation or the Pod’s specification, is applied to the first process run in
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each Container.
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**Note**: When a Pod consumes a PersistentVolume, the GIDs associated with the
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PersistentVolume are not present on the Pod resource itself.
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{% endcapture %}
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{% capture whatsnext %}
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* Learn more about [PersistentVolumes](/docs/user-guide/persistent-volumes/).
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* Read the [Persistent Storage design document](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/persistent-storage.md).
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### Reference
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* [PersistentVolume](/docs/resources-reference/v1.5/#persistentvolume-v1)
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* [PersistentVolumeSpec](/docs/resources-reference/v1.5/#persistentvolumespec-v1)
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* [PersistentVolumeClaim](/docs/resources-reference/v1.5/#persistentvolumeclaim-v1)
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* [PersistentVolumeClaimSpec](/docs/resources-reference/v1.5/#persistentvolumeclaimspec-v1)
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{% endcapture %}
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{% include templates/task.md %}
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@ -0,0 +1,10 @@
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kind: PersistentVolumeClaim
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apiVersion: v1
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metadata:
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name: task-pv-claim
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spec:
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accessModes:
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- ReadWriteOnce
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resources:
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requests:
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storage: 3Gi
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kind: Pod
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apiVersion: v1
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metadata:
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name: task-pv-pod
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spec:
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volumes:
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- name: task-pv-storage
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persistentVolumeClaim:
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claimName: task-pv-claim
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containers:
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- name: task-pv-container
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image: nginx
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ports:
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- containerPort: 80
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name: "http-server"
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volumeMounts:
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- mountPath: "/usr/share/nginx/html"
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name: task-pv-storage
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kind: PersistentVolume
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apiVersion: v1
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metadata:
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name: task-pv-volume
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labels:
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type: local
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spec:
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capacity:
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storage: 10Gi
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accessModes:
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- ReadWriteOnce
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hostPath:
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path: "/tmp/data"
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