Persistent volume claim not claiming the volume - kubernetes

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"

Answer 1

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.