Permission issue with Persistent volume in postgres in Kubernetes

Question

I know this question has been asked repeatedly but not fully answered. I have a postgres running in as root user in a container which is using the persistent volume. But it seems like there is permission issue issue in mounting in the container. Container logs

  `The files belonging to this database system will be owned by user
"postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.utf8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /data ... ok
initdb: could not create directory "/data/pg_xlog": Permission denied
initdb: removing contents of data directory "/data"`

Persistent Volume and Persistent Volume Claim:

kind: PersistentVolume
apiVersion: v1
metadata:
  name: store-persistent-volume
  labels:
    app: pgmaster
  namespace: pustakalaya
spec:
  storageClassName: manual
  capacity:
    storage: 5Gi
  accessModes:
  - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  hostPath:
    path: "/library/pgmaster-data"

---

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: store-persistent-volume-claim
  labels:
    app: postgres
  namespace: pustakalaya
spec:
  storageClassName: manual
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 3Gi

and Pod file:

spec:
  selector:
    matchLabels:
      app: pgmaster
  replicas: 1
  template:
    metadata:
      labels:
        app: pgmaster
    spec:
     # initContainers:
     #   - name: chmod-er
     #     image: busybox:latest
     #     command: ['sh', '-c' ,'/bin/chmod -R 777 /data && /bin/chown -R 999:999 /data']
      containers:
        - name: pgmaster
          image: becram/olen-elib-db-master:v5.3.0
          env:
            - name: POSTGRES_DB
              value: pustakalaya
            - name: POSTGRES_USER
              value: pustakalaya_user
            - name: POSTGRES_PASSWORD
              value: pustakalaya123
            - name: PGDATA
              value: /data
            - name: POSTGRES_BACKUP_DIR
              value: /backup
          ports:
            - containerPort: 5432
          volumeMounts:
          - mountPath: /data:rw
            name: pgmaster-volume
#      restartPolicy: Always
      volumes:
       - name: pgmaster-volume
         persistentVolumeClaim:
           claimName: store-persistent-volume-claim

I believe that root of your issue is in following: In postgres, even when you start it as a root user, process still drops root permission and runs as "postgres" user. So, try to ensure that postgres user has permissions to write in /data directory. Hope it helps. — getslaf
– getslaf, Commented Dec 13, 2018 at 11:59
@getslaf sorry I missed a important information. The volume I am using is synced directory in vagrant and the problem seems to be different than I thought. This works fine if I persist data in guest VM itself except the synced folder. — Bikram
– Bikram, Commented Dec 16, 2018 at 4:51
I was facing the same issue, and according to the suggestion, I provided the permission like command: ["/bin/sh", "-c", "chmod -R 777 /data"]. But after that, container is not showing any logs and not getting started. — mohit sharma
– mohit sharma, Commented May 15, 2019 at 6:59
Did you solve this at the end? I am facing the same issue, any help would be appreciated. Thanks — Javier Guzmán
– Javier Guzmán, Commented Jan 26, 2021 at 9:52

MGLondon · Accepted Answer · 2021-03-03 16:01:22Z

1

I was having the same issue with Minikube. I solved it with a manual approach. Since the folder is created on the host machine - which is running the node, I ssh-ed into the cluster. On Minikube you could do this by:

minikube ssh

Next, find the folder on the cluster host machine and manually change the permissions.

chmod -R 777 /myfolder
chown -R 999:999 /myfolder

After this, I executed the manifest files again, and it ran without a problem. So to fix this, you need to change permissions from your cluster machine and not from your container.

edited Mar 3, 2021 at 16:01

answered Feb 22, 2021 at 11:10

MGLondon

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