fix: postgres 18+ OpenShift compatibility

[syangsao]

Problem

PostgreSQL pod fails to start on OpenShift with two errors:

1. chmod: /var/run/postgresql: Operation not permitted — OpenShift runs containers as a random non-root UID, but the postgres:18-alpine entrypoint tries to chmod directories without a pod-level fsGroup security context.

2. PostgreSQL data in /var/lib/postgresql/data (unused mount/volume) — Docker image postgres:18+ changed the data directory structure. Instead of mounting at /var/lib/postgresql/data, you now mount at /var/lib/postgresql and the image creates versioned subdirectories like data-18/. See Change PGDATA in 18+ to /var/lib/postgresql/MAJOR/docker docker-library/postgres#1259

Fix

• Added fsGroup: 7000 pod-level securityContext — OpenShift chowns the mounted volume to GID 7000 (the postgres group in Alpine), resolving the permission error.
• Changed mountPath from /var/lib/postgresql/data → /var/lib/postgresql — matches the new volume structure for postgres:18+ images.

Notes

If you have an existing PVC with data, the old data lives under data/ on the volume. Postgres 18+ expects it under data-18/. You'll need to either:

• Move the data: mv /var/lib/postgresql/data/* /var/lib/postgresql/
• Or delete and recreate the PVC (loses data)

Fresh deployments are unaffected.