Kubernetes - Create a (default) StorageClass using the nfs-subdir provisioner

Using a default storage class will allow you to deploy volumes as they are claimed / requested without any manual intervention. Kubernetes provides multiple built-in storage provisioners but most of them are focused on cloud environments and since I run my cluster on-prem with nfs as shared storage, I will have to use the nfs-subdir external provisioner (github).

This will allow me to share one directory and the provisioner will create a directory on the nfs share for each volume that is being allocated. For more documentation, check the link above.

First, clone the git repository:

 [ 17:25:09 ] - archy ~> git clone https://github.com/kubernetes-sigs/nfs-subdir-external-provisioner.git git/kubernetes/prod/nfs-subdir-external-provisioner  
 [ 17:25:10 ] - archy ~> cd git/kubernetes/prod/nfs-subdir-external-provisioner

Create the RBAC Bindings required for the provisioner to work:

 [ 17:25:24 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> kubectl -n default apply -f deploy/rbac.yaml

I will adjust some values in 'deploy/deployment.yaml' since my nfs-server and path differ from the defaults:

 [ 17:26:04 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> git diff deploy/deployment.yaml  
 diff --git a/deploy/deployment.yaml b/deploy/deployment.yaml  
 index 26d2a23..e07e5f6 100644  
 --- a/deploy/deployment.yaml  
 +++ b/deploy/deployment.yaml  
 @@ -29,11 +29,11 @@ spec:  
             - name: PROVISIONER_NAME  
               value: k8s-sigs.io/nfs-subdir-external-provisioner  
             - name: NFS_SERVER  
 -             value: 10.3.243.101  
 +             value: nfssrv.archyslife.lan  
             - name: NFS_PATH  
 -             value: /ifs/kubernetes  
 +             value: /var/nfs/kubernetes  
       volumes:  
         - name: nfs-client-root  
           nfs:  
 -           server: 10.3.243.101  
 -           path: /ifs/kubernetes  
 +           server: nfssrv.archyslife.lan  
 +           path: /var/nfs/kubernetes

Apply the modified deployment:

 [ 17:26:09 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> kubectl -n default apply -f deploy/deployment.yaml

I will also adjust the path pattern with which the directories are created and make the storageclass my default storage class using the annotation below. I also added a pattern after which the directories will be created:

 [ 17:27:36 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> git diff deploy/class.yaml  
 diff --git a/deploy/class.yaml b/deploy/class.yaml  
 index fbbf086..a676814 100644  
 --- a/deploy/class.yaml  
 +++ b/deploy/class.yaml  
 @@ -1,7 +1,10 @@  
  apiVersion: storage.k8s.io/v1  
  kind: StorageClass  
  metadata:  
 -  name: nfs-client  
 +  name: managed-nfs  
 +  annotations:  
 +    storageclass.kubernetes.io/is-default-class: "true"  
  provisioner: k8s-sigs.io/nfs-subdir-external-provisioner # or choose another name, must match deployment's env PROVISIONER_NAME'  
  parameters:  
 +  pathPattern: "${.PVC.namespace}-${.PVC.name}"  
    archiveOnDelete: "false"

Apply the modified storage class:

 [ 17:26:44 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> kubectl -n default apply -f deploy/class.yaml

You should now have a default storage class managed by the k8s-sigs.io/nfs-subdir-external-provisioner but you can check using this command:

 [ 17:29:10 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> kubectl -n default -o wide -l app=nfs-client-provisioner get pods,deployments

So let's test if everything works as expected. Thankfully, the maintainers provided two test yamls that will create a volumeclaim and pod that will access said volume, so apply them:

 [ 17:29:21 ] - archy ~/git/kubernetes/prod/nfs-subdir-external-provisioner - master> kubectl -n default apply -f deploy/test-claim.yaml -f deploy/test-pod.yaml

Now you can check on your nfs server with under the specified volume path for a file called 'SUCCESS':

 [17:29:44 - archy@nfssrv ~]$ ls -lh /var/nfs/kubernetes  
 total 0  
 drwxrwxrwx. 2 root root 6 Sep 13 17:29 default-test-claim  
 [17:29:50 - archy@nfssrv ~]$ ls -lh /var/nfs/kubernetes/default-test-claim  
 total 0  
 -rw-r--r--. 1 root root 0 Sep 13 17:29 SUCCESS

As you can see, the default storage class works and is applied. This concludes the setup of a default storage class using the nfs-subdir-external-provisioner in kubernetes.

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