Kubernetes : Dynamic Storage Provisioning using host-path [closed]

Question

My question is about PersistentVolumeClaim I have one node cluster setup on aws ec2 I am trying to create a storage class using kubernetes.io/host-path as Provisioner.

yaml file content for storage class as follows,

kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
namespace: kube-system
name: my-storage
annotations:
    storageclass.beta.kubernetes.io/is-default-class: "false"
labels:
    kubernetes.io/cluster-service: "true"
provisioner: kubernetes.io/host-path

yaml file content for PersistentVolumeClaim as follows,

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: task-pv-claim
annotations:
    volume.beta.kubernetes.io/storage-class: my-storage
spec:
accessModes:
    - ReadWriteOnce
resources:
    requests:
    storage: 3Gi

When I am trying to create storage class and PVC on minikube, it's working. It is creating volume on minikube in /tmp/hostpath_volume/ But, When I am trying similar thing on one node cluster setup on aws ec2, I am getting following error

Failed to create provisioner: Provisioning in volume plugin "kubernetes.io/host-path" is disabled

I can see this error when I do the kubectl describe pvc task-pv-claim, Also as, PV is not created, so claim is in pending state

I found something like kube-controller-manager which shows --enable-dynamic-provisioning and --enable-hostpath-provisioner in its option but don't know how to use it.

Slr

What version of kubernetes are you running? Is the hostpath provisioner running as a pod in your cluster? – Gunmaker

I am using kubectl version 1.5.2. I didn't get your second question. I am newbie for this k8s and all. Did you mean 'kubernetes.io/host-path' running as a pod? – Slr

Answer 1

It seems you might not be running the provisioner itself, so there's nothing to actually do the work of creating the hostpath directory.

Take a look here

The way this works is that the hostpath provisioner reads from the kubernetes API, and watches for you to create a storage class (which you've done) and a persistentvolumeclaim (also done).

When those exist, the provisioner (which is running as a pod) will go an execute a mkdir to create the hostpath.

Run the following:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-incubator/external-storage/master/docs/demo/hostpath-provisioner/pod.yaml

And then recreate your storageclass and pvc

Gunmaker

Your solution seems totally perfect. Thanks for that sir. But, I am facing issue while doing your solution. When I tried to execute command given by you, pod got deployed but with 'ErrImagePull' status. Then I tried pulling image from hub.docker.com/r/jaxxstorm/hostpath-provisioner/tags and tried deploying but getting "F0406 19:52:27.642967 7 hostpath-provisioner.go:125] Failed to create config: unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined" Can you please help me out here? – Slr

by default, kubernetes should map a token so it can talk to the API, but in your case that isn't happening. It seems your cluster isn't functioning correctly. I would open a new question, and detail how exactly you bootstrapped your cluster – Gunmaker

@Slr we chatted on slack, can you accept the answer – Gunmaker

It seems that example code from the answer was moved to github.com/kubernetes-sigs/sig-storage-lib-external-provisioner/… Although the documentation was not kept. It still can be found here github.com/kubernetes-incubator/external-storage/tree/… – Negrete

Answer 2

On a single-node cluster you can enable the HostPath provisioner in the kube-controller-manager via the following flag:

--enable-hostpath-provisioner=true

Then you create a storage class for the HostPath provisioner:

cat <<EOF | kubectl create -f -
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
  name: standard
provisioner: kubernetes.io/host-path
reclaimPolicy: Delete
volumeBindingMode: Immediate
EOF

Once the storage class is created you can provision persistent volumes dynamically:

cat <<EOF | kubectl create -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-dynamic-test
spec:
  storageClassName: standard
  resources:
    requests:
      storage: 1G
  accessModes:
  - ReadWriteOnce
EOF

kubectl get pv

Boron