Guidance on upgrading GitLab Helm Chart from 8.8.0 to 9.0.0 with PostgreSQL migration

Summary

We are trying to upgrade our GitLab Helm Chart deployment from 8.8.0 → 9.0.0. The new chart version introduces PostgreSQL v17, but our current deployment is running PostgreSQL v14.8.0. We would like guidance on the safest upgrade path to avoid downtime or data loss.

Steps to reproduce

Deploy GitLab using Helm chart version 8.8.0:

helm upgrade --install gitlab gitlab/gitlab -n gitlab --version 8.8.0

Attempt upgrade to chart version 9.0.0:

helm upgrade --install gitlab gitlab/gitlab -n gitlab --version 9.0.0

Note that chart 9.0.0 includes PostgreSQL 17 while the current database is PostgreSQL 14.8.0.

Current behavior

Current GitLab deployment is running fine on Helm chart 8.8.0 with PostgreSQL 14.8.0.

Concern: upgrading directly to 9.0.0 may cause issues due to the database version jump.

Expected behavior

Clear upgrade path from 8.8.0 → 9.0.0 with PostgreSQL migration handled safely.

No data loss or corruption during/after the upgrade.

Documentation or official guidance on whether an intermediate upgrade path is required.

Versions

Chart: 8.8.0 → 9.0.0

Platform: Self-hosted Kubernetes

Kubernetes (kubectl version): v1.30.0 (Client & Server)

Helm (helm version): v3.13.1 (Client & Server)