Optimize workflow

Only push layers to ghcr.io in build job and copy layers from ghcr.io to
docker.io if necessary in merge job.

Author: simu

.github/workflows/push.yml

@@ -88,12 +88,6 @@ jobs:
         echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
     - name: checkout
       uses: actions/checkout@v6
-    - name: Login to docker.io
-      uses: docker/login-action@v4
-      with:
-        registry: docker.io
-        username: ${{ secrets.DOCKER_USERNAME }}
-        password: ${{ secrets.DOCKER_PASSWORD }}
     - name: Login to ghcr.io
       uses: docker/login-action@v4
       with:
@@ -106,14 +100,8 @@ jobs:
       with:
         images: |
           ${{ env.GHCR_IMAGE }}
-          ${{ github.event_name != 'pull_request' && env.DOCKER_IMAGE || '' }}
         tags: |
           type=raw,value=${{ needs.get-version.outputs.tag }},enable=true
-    - name: Extract Docker image name list
-      id: image-names
-      run: |
-        cat ${DOCKER_METADATA_OUTPUT_BAKE_FILE_TAGS}
-        echo "names=$(jq -r '.target["docker-metadata-action"].args.DOCKER_META_IMAGES' ${DOCKER_METADATA_OUTPUT_BAKE_FILE_TAGS})" >> ${GITHUB_OUTPUT}
     - name: Set up Docker context for Buildx
       run: |
         docker context create builders
@@ -133,7 +121,7 @@ jobs:
         labels: ${{ steps.meta.outputs.labels }}
         annotations: ${{ steps.meta.outputs.annotations }}
         outputs: |
-          type=image,"name=${{ steps.image-names.outputs.names }}",push-by-digest=true,name-canonical=true,push=true,oci-mediatypes=true
+          type=image,name=${{ env.GHCR_IMAGE }},push-by-digest=true,name-canonical=true,push=true,oci-mediatypes=true
         cache-from: type=gha,scope=${{ github.repository }}-${{ github.ref_name }}-${{ matrix.platform }}
         cache-to: type=gha,mode=max,scope=${{ github.repository }}-${{ github.ref_name }}-${{ matrix.platform }}
         build-args: |
@@ -206,6 +194,8 @@ jobs:
       with:
         images: |
           ${{ env.GHCR_IMAGE }}
+          ${{ env.DOCKER_IMAGE }}
+          ${{ github.event_name != 'pull_request' && env.DOCKER_IMAGE || '' }}
         annotations: |
           type=org.opencontainers.image.description,value=${{ github.event.repository.description || 'No description provided' }}
         tags: |
@@ -223,26 +213,6 @@ jobs:
     - name: Inspect ghcr.io image
       run: |
         docker buildx imagetools inspect '${{ env.GHCR_IMAGE }}:${{ needs.get-version.outputs.tag }}'
-
-    - name: Generate Docker metadata for docker.io
-      uses: docker/metadata-action@v6
-      with:
-        images: |
-          ${{ env.DOCKER_IMAGE }}
-        annotations: |
-          type=org.opencontainers.image.description,value=${{ github.event.repository.description || 'No description provided' }}
-        tags: |
-          type=raw,value=${{ needs.get-version.outputs.tag }},enable=true
-    - name: Create manifest list and push to docker.io
-      working-directory: /tmp/digests
-      run: |
-        docker buildx imagetools create \
-          $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
-          --annotation='index:org.opencontainers.image.description=${{ github.event.repository.description }}' \
-          --annotation='index:org.opencontainers.image.created=${{ steps.timestamp.outputs.timestamp }}' \
-          --annotation='index:org.opencontainers.image.url=${{ github.event.repository.url }}' \
-          --annotation='index:org.opencontainers.image.source=${{ github.event.repository.url }}' \
-          $(printf '${{ env.GHCR_IMAGE }}@sha256:%s ' *)
     - name: Inspect docker.io image
       run: |
         docker buildx imagetools inspect '${{ env.DOCKER_IMAGE }}:${{ needs.get-version.outputs.tag }}'