How to fix FATAL: data directory has invalid permissions in PostgreSQL

Connect to your container or server and check the actual permissions:

ls -ld /var/lib/postgresql/data

You'll see output like drwx------ (0700) which is correct, or drwxr-xr-x (0755) which is wrong. The directory should show only the first three permission bits set (owner rwx only).

Verify the data directory is owned by the PostgreSQL system user:

ls -ld /var/lib/postgresql/data

The output should show ownership by the postgres user (or equivalent PostgreSQL user). If it's owned by root or another user, this is the problem.

If the permissions are not 0700 or 0750, fix them with:

chmod 700 /var/lib/postgresql/data

For Docker containers, you may need to run this as root or with sudo. For Kubernetes, add this to your init container.

If the directory is owned by the wrong user, change ownership to the PostgreSQL user:

chown postgres:postgres /var/lib/postgresql/data

On some systems, the PostgreSQL user may be named differently (check /etc/passwd for the correct name).

In your Dockerfile or docker-compose.yml, add a step that ensures correct permissions before PostgreSQL starts:

services:
  postgres:
    image: postgres:15
    volumes:
      - postgres_data:/var/lib/postgresql/data
    entrypoint: |
      bash -c "
      chmod 700 /var/lib/postgresql/data
      docker-entrypoint.sh postgres"

Alternatively, use an init container in Kubernetes (see next step).

Add an init container to your Kubernetes StatefulSet or Pod that sets correct permissions:

initContainers:
- name: init-chmod-data
  image: busybox:1.28
  command:
  - sh
  - -c
  - chmod 700 /var/lib/postgresql/data || true
  volumeMounts:
  - name: postgres-data
    mountPath: /var/lib/postgresql/data

This runs before the PostgreSQL container starts and ensures permissions are correct even if the volume was mounted with wrong permissions.