ci(docker): auto-detect Docker Hub credentials for dual-registry publish

[parth0025]

Summary

Adds optional Docker Hub publishing alongside the existing GHCR publishing. The workflow auto-detects whether Docker Hub credentials are configured and adapts at runtime — so this PR can merge now, before the official Docker Hub account exists, and start working the moment the secrets are added later.

Why merge before the account is ready

The team will set up an official Docker Hub account later. Rather than leave commented-out code that needs editing in three places when that happens, this workflow:

• ✅ Runs exactly as today (GHCR only) while no Docker Hub secrets exist — zero behavior change on merge
• ✅ Auto-detects DOCKERHUB_USERNAME on each run and, when present, publishes to Docker Hub too
• ✅ Needs no code change when the account is ready — just add the secrets

How it behaves

State	GHCR	Docker Hub
Today (no secrets)	✅ Publishes	⏭️ Skipped cleanly
After secrets added	✅ Publishes	✅ Publishes (same tag set)

Namespace is account-name-agnostic

The image namespace defaults to alianhub (docker.io/alianhub/alianhub) but is overridable without editing the workflow, via the repo variable DOCKERHUB_NAMESPACE:

Official account scenario	Secrets / variables to set
Standalone account named alianhub	DOCKERHUB_USERNAME=alianhub + token. Namespace defaults to alianhub ✓
Account named something else (e.g. aliansoftware)	DOCKERHUB_USERNAME=aliansoftware + token + set variable DOCKERHUB_NAMESPACE=aliansoftware
Personal login pushing into a brand org	DOCKERHUB_USERNAME=<personal-login> + token + DOCKERHUB_NAMESPACE=alianhub

This covers every account shape without a future code edit.

Files changed (1)

File	Change
.github/workflows/docker.yml	New "Detect Docker Hub credentials" step (emits enabled + namespace outputs); conditional Docker Hub login step; format() expression in metadata images: list; updated header docs

Diff: +54 / -16.

What you (the team) do when the official account is ready

1. Create the official Docker Hub account/org
2. Generate a Docker Hub access token (Read + Write)
3. Add repo secrets:

   gh secret set DOCKERHUB_USERNAME --body "<account>" --repo aliansoftwareteam/AlianHub-Project-Management-System
   gh secret set DOCKERHUB_TOKEN --body "dckr_pat_..." --repo aliansoftwareteam/AlianHub-Project-Management-System

4. (Only if namespace ≠ alianhub) add the variable:

   gh variable set DOCKERHUB_NAMESPACE --body "<namespace>" --repo aliansoftwareteam/AlianHub-Project-Management-System

5. Trigger workflow_dispatch on the Docker workflow (or wait for the next release) → image publishes to Docker Hub

Test plan

• After merge, with NO Docker Hub secrets set: push to main / cut a release → workflow publishes to GHCR only, "Detect Docker Hub credentials" step logs "publishing to GHCR only", no failure
• After adding secrets: trigger workflow_dispatch → workflow logs "will publish to docker.io//alianhub", both registries get the image
• Verify GHCR publishing is unaffected (still publishes latest, version tags, edge, main-<sha> as before)

Compatibility

✅ GHCR publishing path is unchanged — still the always-on default
✅ No new required secrets — Docker Hub is purely additive and optional
✅ No conflict with other files — touches only .github/workflows/docker.yml

🤖 Generated with Claude Code

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