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[string], optional) A 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 +24,16 @@ 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
+    default: []
 outputs:
   tag:
     description: "The tag of the Docker image that was built."
@@ -61,9 +71,12 @@ 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 }}
+          ${{ join('\n', fromJSON(inputs.additional-tags) }}
         cache-from: type=gha
         cache-to: type=gha,mode=max