Add custom Docker image publishing to the existing workflow

.github/workflows/changesets_release.yml

@@ -71,7 +71,7 @@ jobs:
     uses: ./.github/workflows/sync_service_dockerhub_image.yml
     secrets: inherit
     with:
-      release_tag: ${{ needs.changesets.outputs.sync_service_release_tag }}
+      git_ref: ${{ needs.changesets.outputs.sync_service_release_tag }}
 
   update-cloud:
     name: Update Electric version used by Cloud

.github/workflows/sync_service_dockerhub_image.yml

@@ -10,17 +10,25 @@ on:
   # Allows the workflow to be called by the Changesets workflow
   workflow_call:
     inputs:
-      release_tag:
-        description: 'The @core/sync-service@... tag passed from caller'
+      git_ref:
+        description: 'Git ref to build from (branch name, tag, or commit SHA)'
         required: true
         type: string
+      docker_tag:
+        description: 'Optional Docker Hub tag override (derived from git_ref if omitted)'
+        required: false
+        type: string
   # Allows the workflow to be triggered manually from the UI
   workflow_dispatch:
     inputs:
-      release_tag:
-        description: 'The @core/sync-service@... tag to run the workflow for (e.g. @core/sync-service@1.2.10)'
+      git_ref:
+        description: 'Git ref to build from (branch name, tag, or commit SHA)'
         required: true
         type: string
+      docker_tag:
+        description: 'Optional Docker Hub tag override (derived from git_ref if omitted)'
+        required: false
+        type: string
 
 env:
   DOCKERHUB_REPO: electricsql/electric
@@ -32,31 +40,38 @@ jobs:
     runs-on: blacksmith-2vcpu-ubuntu-2404
     outputs:
       git_ref: ${{ steps.git_ref.outputs.git_ref }}
-      is_release: ${{ steps.git_ref.outputs.is_release }}
+      build_mode: ${{ steps.git_ref.outputs.build_mode }}
       short_commit_sha: ${{ steps.vars.outputs.short_commit_sha }}
       electric_version: ${{ steps.vars.outputs.electric_version }}
+      docker_tag: ${{ steps.vars.outputs.docker_tag }}
 
     steps:
       - name: Determine the ref to check out
         id: git_ref
         env:
-          INPUT_RELEASE_TAG: ${{ inputs.release_tag }}
+          INPUT_GIT_REF: ${{ inputs.git_ref }}
+          INPUT_DOCKER_TAG: ${{ inputs.docker_tag }}
           EVENT_RELEASE_TAG: ${{ github.event.release.tag_name }}
           COMMIT_SHA: ${{ github.sha }}
         run: |
-          if [ -n "$INPUT_RELEASE_TAG" ]; then
-            ref="refs/tags/$INPUT_RELEASE_TAG"
-            is_release=true
+          if [ -n "$INPUT_DOCKER_TAG" ]; then
+            # Custom docker tag provided — this is a custom build
+            ref="${INPUT_GIT_REF}"
+            build_mode=custom
+          elif [ -n "$INPUT_GIT_REF" ]; then
+            # git_ref provided without docker_tag — treat as a release tag
+            ref="refs/tags/$INPUT_GIT_REF"
+            build_mode=release
           elif [ -n "$EVENT_RELEASE_TAG" ]; then
             ref="refs/tags/$EVENT_RELEASE_TAG"
-            is_release=true
+            build_mode=release
           else
             ref="$COMMIT_SHA"
-            is_release=false
+            build_mode=canary
           fi
 
           echo "git_ref=$ref" >> $GITHUB_OUTPUT
-          echo "is_release=$is_release" >> $GITHUB_OUTPUT
+          echo "build_mode=$build_mode" >> $GITHUB_OUTPUT
 
       - uses: actions/checkout@v4
         with:
@@ -68,16 +83,18 @@ jobs:
           # For releases we check out the tag corresponding to the release, e.g.
           # @core/sync-service@v1.2.10.
           #
-          # For manual triggers via workflow_dispatch, we check out the tag specified manually
-          # by the actor.
+          # For custom builds, we check out the branch, tag, or SHA specified by the caller.
           ref: ${{ steps.git_ref.outputs.git_ref }}
-          # Also important to fetch the whole history since otherwise we won't get that tags
+          # Also important to fetch the whole history since otherwise we won't get the tags
           # that are required to determine the correct ELECTRIC_VERSION.
           fetch-depth: 0
           fetch-tags: true
 
-      - name: Determine short_commit_sha and electric_version to use in the build step
+      - name: Determine short_commit_sha, electric_version, and docker_tag
         id: vars
+        env:
+          BUILD_MODE: ${{ steps.git_ref.outputs.build_mode }}
+          INPUT_DOCKER_TAG: ${{ inputs.docker_tag }}
         run: |
           echo "short_commit_sha=$(
             git rev-parse --short HEAD
@@ -87,6 +104,16 @@ jobs:
             git describe --abbrev=7 --tags --always --first-parent --match '@core/sync-service@*' | sed -En 's|^@core/sync-service@||p'
           )" >> $GITHUB_OUTPUT
 
+          # Determine the docker tag to use
+          if [ -n "$INPUT_DOCKER_TAG" ]; then
+            docker_tag="$INPUT_DOCKER_TAG"
+          elif [ "$BUILD_MODE" = "release" ]; then
+            docker_tag="$electric_version"
+          else
+            docker_tag="canary"
+          fi
+          echo "docker_tag=$docker_tag" >> $GITHUB_OUTPUT
+
   build_and_push_image:
     strategy:
       matrix:
@@ -120,7 +147,7 @@ jobs:
           build-contexts: |
             electric-telemetry=packages/electric-telemetry
           build-args: |
-            ELECTRIC_VERSION=${{ needs.derive_build_vars.outputs.electric_version }}
+            ELECTRIC_VERSION=${{ needs.derive_build_vars.outputs.build_mode == 'custom' && needs.derive_build_vars.outputs.docker_tag || needs.derive_build_vars.outputs.electric_version }}
           platforms: ${{ matrix.platform }}
           push: true
           # push an untagged image and export its digest
@@ -158,16 +185,25 @@ jobs:
           merge-multiple: true
           path: /tmp/digests
 
-      - name: Derive image tags from the GitHub Actions event
+      - name: Derive image tags from the build mode
+        env:
+          BUILD_MODE: ${{ needs.derive_build_vars.outputs.build_mode }}
+          DOCKER_TAG: ${{ needs.derive_build_vars.outputs.docker_tag }}
+          ELECTRIC_VERSION: ${{ needs.derive_build_vars.outputs.electric_version }}
+          SHORT_SHA: ${{ needs.derive_build_vars.outputs.short_commit_sha }}
         run: |
-          if [ "${{ needs.derive_build_vars.outputs.is_release }}" = "true" ]; then
+          if [ "$BUILD_MODE" = "release" ]; then
             # A release triggers official release image publishing
-            echo "ELECTRIC_TAGS=-t $DOCKERHUB_REPO:latest -t $DOCKERHUB_REPO:${{ needs.derive_build_vars.outputs.electric_version }}" >> $GITHUB_ENV
+            echo "ELECTRIC_TAGS=-t $DOCKERHUB_REPO:latest -t $DOCKERHUB_REPO:$ELECTRIC_VERSION" >> $GITHUB_ENV
+            echo "ELECTRIC_CANARY_TAGS=" >> $GITHUB_ENV
+          elif [ "$BUILD_MODE" = "custom" ]; then
+            # A custom build publishes with the caller-specified tag only
+            echo "ELECTRIC_TAGS=-t $DOCKERHUB_REPO:$DOCKER_TAG" >> $GITHUB_ENV
             echo "ELECTRIC_CANARY_TAGS=" >> $GITHUB_ENV
           else
             # A regular push to the main branch triggers canary image publishing
             echo "ELECTRIC_TAGS=-t $DOCKERHUB_REPO:canary" >> $GITHUB_ENV
-            echo "ELECTRIC_CANARY_TAGS=-t $DOCKERHUB_CANARY_REPO:latest -t $DOCKERHUB_CANARY_REPO:${{ needs.derive_build_vars.outputs.short_commit_sha }}" >> $GITHUB_ENV
+            echo "ELECTRIC_CANARY_TAGS=-t $DOCKERHUB_CANARY_REPO:latest -t $DOCKERHUB_CANARY_REPO:$SHORT_SHA" >> $GITHUB_ENV
           fi
 
       - name: Create multi-arch manifest list
@@ -181,7 +217,7 @@ jobs:
             done
           )
 
-          # Create a manifest list for $DOCKERHUB_REPO:canary that includes both platforms
+          # Create a manifest list that includes both platforms
           docker buildx imagetools create $ELECTRIC_TAGS $ELECTRIC_IMAGES
 
           if [ -n "$ELECTRIC_CANARY_TAGS" ]; then