Persistent volume claim not claiming the volume

Question

I have this persistent volume claim

$ kubectl get pvc -ngitlab-managed-apps
NAME                           STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
prometheus-prometheus-server   Pending                                                     0s


$ kubectl describe pvc prometheus-prometheus-server -ngitlab-managed-apps
Name:          prometheus-prometheus-server
Namespace:     gitlab-managed-apps
StorageClass:  
Status:        Pending
Volume:        
Labels:        app=prometheus
               chart=prometheus-9.5.2
               component=server
               heritage=Tiller
               release=prometheus
Annotations:   <none>
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      
Access Modes:  
VolumeMode:    Filesystem
Mounted By:    prometheus-prometheus-server-78bdf8f5b7-pkvcr
Events:
  Type    Reason         Age                From                         Message
  ----    ------         ----               ----                         -------
  Normal  FailedBinding  14s (x5 over 60s)  persistentvolume-controller  no persistent volumes available for this claim and no storage class is set

And I have created this persistent volume

$ kubectl get pv
NAME                           CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                                              STORAGECLASS   REASON   AGE
prometheus-prometheus-server   8Gi        RWO            Retain           Released   gitlab-managed-apps/prometheus-prometheus-server   manual                  17m

$ kubectl describe pv prometheus-prometheus-server
Name:            prometheus-prometheus-server
Labels:          type=local
Annotations:     kubectl.kubernetes.io/last-applied-configuration:
                   {"apiVersion":"v1","kind":"PersistentVolume","metadata":{"annotations":{},"labels":{"type":"local"},"name":"prometheus-prometheus-server"}...
                 pv.kubernetes.io/bound-by-controller: yes
Finalizers:      [kubernetes.io/pv-protection]
StorageClass:    manual
Status:          Released
Claim:           gitlab-managed-apps/prometheus-prometheus-server
Reclaim Policy:  Retain
Access Modes:    RWO
VolumeMode:      Filesystem
Capacity:        8Gi
Node Affinity:   <none>
Message:         
Source:
    Type:          HostPath (bare host directory volume)
    Path:          /var/prometheus-server
    HostPathType:  
Events:            <none>

Why is the claim not claiming the volume? Besides the name, is there anything else that needs to match? Are there any logs I should look into? For now I only see "no persistent volumes available for this claim and no storage class is set"

Have you figured out your problem? I've updated my answer. Let me know if it doesn't solve your problem. — Kamol Hasan, Aug 24 '20 at 12:27

Kamol Hasan · Answer 1 · 2020-08-24T12:25:44.217

To understand the error message, you need to understand how static and dynamic provisioning work.

When none of the static PVs the administrator created matches a user's PersistentVolumeClaim, the cluster may try to dynamically provision a volume especially for the PVC. This provisioning is based on StorageClasses.

After you create the PersistentVolumeClaim, the Kubernetes control plane looks for a PersistentVolume that satisfies the claim's requirements. If the control plane finds a suitable PersistentVolume with the same StorageClass, it binds the claim to the volume.

Your error says,"Your PVC hasn't found a matching PV and you also haven't mentioned any storageClass name".

Your PV has StorageClass: manual, but your PVC doesn't have any storageClass (StorageClass: ""). Adding StorageClass: manual to your PVC should solve your problem.

You must need to choose one of the following provisioning options.

Static provisioning:

create PV
create PVC with the label selector, so that it can find the PV with labels mentioned.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  selector: # <----- here
    matchLabels:
      release: "stable"
... ...

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
  label: # <---- here
    release: "stable"

Dynamic provisioning:

create storageClass with provisioner mentioned
create PVC with the storageClass name mentioned

Or

create both PV and PVC with the same storageClass name mentioned.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: slow
provisioner: some-provisioner 
... ... ...

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  storageClassName: slow # <---- here
... ... ...

This is a short description, please visit the official doc for more details.

Persistent volume claim not claiming the volume

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