[ci] Push branch-tagged docker images to ghcr.io for local testing (#16992)

.github/workflows/ci-docker.yml

@@ -22,7 +22,7 @@ on:
       - "script/platformio_install_deps.py"
 
 permissions:
-  contents: read  # actions/checkout only; the build does not push images
+  contents: read  # actions/checkout only
 
 concurrency:
   # yamllint disable-line rule:line-length
@@ -33,6 +33,9 @@ jobs:
   check-docker:
     name: Build docker containers
     runs-on: ${{ matrix.os }}
+    permissions:
+      contents: read   # actions/checkout to load Dockerfile and build context
+      packages: write  # push branch-tagged images to ghcr.io for local testing
     strategy:
       fail-fast: false
       matrix:
@@ -41,6 +44,9 @@ jobs:
           - "ha-addon"
           - "docker"
           # - "lint"
+    outputs:
+      tag: ${{ steps.tag.outputs.tag }}
+      push: ${{ steps.tag.outputs.push }}
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       - name: Set up Python
@@ -50,14 +56,82 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@d7f5e7f509e45cec5c76c4d5afdd7de93d0b3df5 # v4.1.0
 
-      - name: Set TAG
+      - name: Determine tag and whether to push
+        id: tag
         run: |
-          echo "TAG=check" >> $GITHUB_ENV
+          # Sanitize the branch name into a valid docker tag: replace invalid
+          # characters, ensure the first character is valid (tags must start
+          # with [A-Za-z0-9_]), and cap the length at 128 characters.
+          branch="${{ github.head_ref || github.ref_name }}"
+          tag="${branch//[^a-zA-Z0-9_.-]/-}"
+          case "$tag" in
+            [a-zA-Z0-9_]*) ;;
+            *) tag="pr-${tag}" ;;
+          esac
+          tag="${tag:0:128}"
+          echo "tag=${tag}" >> "$GITHUB_OUTPUT"
+          # Only push branch images for same-repo pull requests. Push events
+          # only fire for dev/beta/release, whose images are owned by the
+          # release pipeline -- never overwrite those from here.
+          if [ "${{ github.event_name }}" = "pull_request" ] \
+            && [ "${{ github.repository }}" = "esphome/esphome" ] \
+            && [ "${{ github.event.pull_request.head.repo.full_name }}" = "esphome/esphome" ]; then
+            echo "push=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "push=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Log in to the GitHub container registry
+        if: steps.tag.outputs.push == 'true'
+        uses: docker/login-action@650006c6eb7dba73a995cc03b0b2d7f5ca915bee # v4.2.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Run build
         run: |
           docker/build.py \
-            --tag "${TAG}" \
+            --tag "${{ steps.tag.outputs.tag }}" \
             --arch "${{ matrix.os == 'ubuntu-24.04-arm' && 'aarch64' || 'amd64' }}" \
             --build-type "${{ matrix.build_type }}" \
-            build
+            --registry ghcr \
+            build ${{ steps.tag.outputs.push == 'true' && '--push --no-cache-to' || '' }}
+
+  manifest:
+    name: Push ${{ matrix.build_type }} manifest to ghcr.io
+    needs: [check-docker]
+    if: needs.check-docker.outputs.push == 'true'
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read   # actions/checkout to run docker/build.py
+      packages: write  # buildx imagetools writes the multi-arch tag to ghcr.io
+    strategy:
+      fail-fast: false
+      matrix:
+        build_type:
+          - "ha-addon"
+          - "docker"
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+      - name: Set up Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: "3.11"
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@d7f5e7f509e45cec5c76c4d5afdd7de93d0b3df5 # v4.1.0
+
+      - name: Log in to the GitHub container registry
+        uses: docker/login-action@650006c6eb7dba73a995cc03b0b2d7f5ca915bee # v4.2.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create and push manifest
+        run: |
+          docker/build.py \
+            --tag "${{ needs.check-docker.outputs.tag }}" \
+            --build-type "${{ matrix.build_type }}" \
+            --registry ghcr \
+            manifest