I have created a deployment in the xyz-namespace namespace, it has PVC. I can create the deployment and able to access it. It is working properly but while scale the deployment from the Kubernetes console then the pod is pending state only.
persistent_claim:
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: jenkins
spec:
accessModes:
- ReadWriteOnce
storageClassName: standard
resources:
requests:
storage: 5Gi
namespace: xyz-namespace
and deployment object is like below.
apiVersion: apps/v1
kind: Deployment
metadata:
name: db-service
labels:
k8s-app: db-service
Name:db-service
ServiceName: db-service
spec:
selector:
matchLabels:
tier: data
Name: db-service
ServiceName: db-service
strategy:
type: Recreate
template:
metadata:
labels:
app: jenkins
tier: data
Name: db-service
ServiceName: db-service
spec:
hostname: jenkins
initContainers:
- command:
- "/bin/sh"
- "-c"
- chown -R 1000:1000 /var/jenkins_home
image: busybox
imagePullPolicy: Always
name: jenkins-init
volumeMounts:
- name: jenkinsvol
mountPath: "/var/jenkins_home"
containers:
- image: jenkins/jenkins:lts
name: jenkins
ports:
- containerPort: 8080
name: jenkins1
- containerPort: 8080
name: jenkins2
volumeMounts:
- name: jenkinsvol
mountPath: "/var/jenkins_home"
volumes:
- name: jenkinsvol
persistentVolumeClaim:
claimName: jenkins
nodeSelector:
nodegroup: xyz-testing
namespace: xyz-namespace
replicas: 1
Deployment is created fine and working as well but When I am trying to Scale the deployment from console then the pod is getting stuck and it's pending state only.
If I removed the persistent volume and then scaled it then it is working fine, but with persistent volume, it is not working.
Your PersistentVolumeClaim is set to:
accessModes:
- ReadWriteOnce
But it should be set to:
accessModes:
- ReadWriteMany
The ReadWriteOnce access mode means, that
the volume can be mounted as read-write by a single node 1.
When you scale your deployment it's most likely scaled to different nodes, therefore you need ReadWriteMany.
1 https://kubernetes.io/docs/concepts/storage/persistent-volumes/
When using standard storage class I assume you are using the default GCEPersisentDisk
Volume PlugIn. In this case you cannot set them at all as they are already set by the storage provider (GCP in your case, as you are using GCE perisistent disks), these disks only support ReadWriteOnce
(RWO) and ReadOnlyMany
(ROX) access modes. If you try to create a ReadWriteMany
(RWX) PV that will never come in a success state (your case when set the PVC with accessModes: ReadWriteMany).
Also if any pod tries to attach a ReadWriteOnce volume on some other node, you’ll get following error:
FailedMount Failed to attach volume "pv0001" on node "xyz" with: googleapi: Error 400: The disk resource 'abc' is already being used by 'xyz'
References from above on this article
As mentioned here and here, NFS is the easiest way to get ReadWriteMany as all nodes need to be able to ReadWriteMany to the storage device you are using for your pods.
Then I would suggest you to use an NFS storage option. In case you want to test it, here is a good guide by Google using its Filestore solution which are fully managed NFS file servers.