Support alternative deployment methods for OpenBao beyond Helm
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## Problem
GitLab Secrets Manager requires OpenBao to be deployed via the GitLab Helm chart on Kubernetes. Beta customers have asked for more deployment flexibility for environments where Helm/Kubernetes is not the preferred deployment method.
## Customer Use Case
> "The second point, the limitations to deploy the vault only through a helm chart. It would be nice to have more options." — Beta customer
## Current State
- OpenBao is deployed exclusively via the [GitLab Helm chart](https://docs.gitlab.com/charts/charts/openbao/)
- GitLab Rails connects to OpenBao via `openbao.url` and `openbao.internal_url` configuration — it is deployment-method agnostic
- The Helm chart handles auto-unseal, TLS, PostgreSQL backend, HA standby setup, and recovery key management
## Possible Future Options
Each option would need its own evaluation for engineering effort and support burden:
- **Docker Compose** — For smaller or non-Kubernetes environments
- **Linux package (Omnibus)** — Bundled with GitLab's existing Linux packages
- **Terraform modules** — For cloud-managed deployments (GCP, AWS, Azure)
- **Operator-based deployment** — For OpenShift or managed Kubernetes platforms
## Considerations
- Helm-only is a reasonable scope constraint for GA
- Each additional deployment path multiplies the test and support matrix
- OpenBao operational complexity (unseal, HA, backup/restore) makes alternative packaging non-trivial
## Related
- Secrets Manager GA Epic: https://gitlab.com/groups/gitlab-org/-/epics/10723
- Operational Readiness Review: https://gitlab.com/gitlab-org/gitlab/-/issues/524750
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