Support optional target and build-args in build action

README.md

@@ -56,6 +56,14 @@ To automatically set that, the above example uses the context variable `${{ gith
 
 - `platforms` (list, optional) List of target platform for build.
 
+- `target` (string, optional) the name of a build stage in the Dockerfile to target for the image. This allows multiple images
+  built from a single Dockerfile, e.g., "runtime-A" and "runtime-B".
+
+- `build-args` (string, optional) A list of build-arguments as newline-delimited `arg=value` string pairs. These may be
+  specified in the Dockerfile as `ARG` statements.
+
+- `additional-tags` (list, optional) A newline-delimited list of additional tags to be added to the built image.
+
 ### Outputs
 
 - `fully_qualified_image_digest` (string) A complete, unique, and immutable identifier for the built image,

action.yaml

@@ -24,6 +24,15 @@ inputs:
   platforms:
     description: "List of target platforms for build"
     required: false
+  target:
+    description: "Name of target stage to build"
+    required: false
+  build-args:
+    description: "List of build-time variables"
+    required: false
+  additional-tags:
+    description: "List of additional tags to add to built image"
+    required: false
 outputs:
   tag:
     description: "The tag of the Docker image that was built."
@@ -41,6 +50,16 @@ runs:
       shell: bash
       run: echo "tag=`bash ${{ github.action_path  }}/docker-tag.sh`" >> ${GITHUB_OUTPUT}
 
+    - name: Docker meta
+      id: meta
+      uses: docker/metadata-action@v5
+      with:
+        images: |
+          ghcr.io/${{ inputs.image }}
+        tags: |
+          type=raw,${{ steps.tag.outputs.tag }}
+          ${{ input.addtional-tags }}
+
     - name: Set up QEMU
       uses: docker/setup-qemu-action@v3
 
@@ -61,9 +80,10 @@ runs:
       with:
         context: "${{ inputs.context }}"
         file: "${{ inputs.dockerfile }}"
+        build-args: "${{ inputs.build-args }}"
+        target: "${{ inputs.target }}"
         push: ${{ fromJSON(inputs.push) == true }}
         platforms: ${{ inputs.platforms }}
-        tags: |
-          ghcr.io/${{ inputs.image }}:${{ steps.tag.outputs.tag }}
+        tags: ${{ steps.meta.output.tags }}
         cache-from: type=gha
         cache-to: type=gha,mode=max