Publish containers tagged with version created by uci releaser (#794)

This repository started using unified CI (uci) a while back to make
tagged releases. This release mechanism is triggered by editing the
`version.json` which in turn triggers a CI workflow to make a tagged
release along with ghithub release etc.

The issue with this approach is that because the tag is created by CI it
does not trigger other CI jobs that listen to `tags: ['v*']` events.
Therefore, since the switch we have only been publishing containers
tagged with `main`.

The changes here resolve this issue by triggering the GHCR publish
workflow whenever releaser wrokflow succeeds. It then fishes out the ref
produced by the releaser workflow to use as tagging. This will then give
us containers tagged by whatever release we make using uci releaser
workflow.

Additionally, it adds `type=sha,format=long` tagging to containers for
easier debugging and deployment of an explicit commit to `main`.

.github/workflows/publish-ghcr.yml

@@ -6,18 +6,38 @@ on:
       - 'main'
     tags:
       - 'v*'
+    workflow_run:
+      workflows: [ Releaser ]
+      types:
+        - completed
   pull_request:
 
 jobs:
+  prepare-checkout:
+    if: github.event_name != 'workflow_run' || github.event.workflow_run.conclusion == 'success'
+    name: Prepare ref
+    runs-on: ubuntu-latest
+    outputs:
+      ref: ${{ github.event_name != 'workflow_run' && github.ref || steps.releaser.outputs.version }}
+    steps:
+      - name: Get version tag from releaser
+        id: releaser
+        if: github.event_name == 'workflow_run'
+        uses: ipdxco/unified-github-workflows/.github/actions/[email protected]
+        with:
+          artifacts-url: ${{ github.event.workflow_run.artifacts_url }}
   publish:
-    name: publish
+    name: Publish
+    needs: [ prepare-checkout ]
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          ref: ${{ needs.prepare-checkout.outputs.ref }}
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Log in to the Container registry
@@ -34,7 +54,8 @@ jobs:
           tags: |
             type=semver,pattern={{raw}}
             type=ref,event=branch
-            type=raw,value=${{ github.ref }}
+            type=sha,format=long
+            type=raw,value=${{ needs.prepare-checkout.outputs.ref }}
       - name: Build and push Docker image
         uses: docker/build-push-action@v6
         with: