Merge pull request #41 from macbre/add/build-arg

Add the optional build-arg input

action.yml

@@ -42,6 +42,12 @@ inputs:
     description: Image tag, e.g. latest. Will overwrite the tag latest tag on a push, and have no effect on a release.
     required: false
 
+  # https://docs.docker.com/build/guide/build-args/
+  build_arg:
+    description: Additional build argument to be passed to the Dockerfile (e.g. NODE_AUTH_TOKEN=s3cr3t)
+    required: false
+    default: "FOO=bar"
+
 runs:
   using: "composite"
   steps:
@@ -84,7 +90,7 @@ runs:
         export BUILD_DATE=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
         export GITHUB_URL=https://github.com/${{ github.repository }}
 
-        echo "::group::Building the Docker image: ${{ inputs.repository }}/${IMAGE_NAME}:${COMMIT_TAG} from ${{ inputs.dockerfile }} in ${{ inputs.context}} context ..."
+        echo "::group::Building the Docker image: ${{ inputs.repository }}/${IMAGE_NAME}:${COMMIT_TAG} from ${{ inputs.dockerfile }} in ${{ inputs.context }} context ..."
 
         # https://docs.docker.com/develop/develop-images/build_enhancements/
         # https://docs.docker.com/engine/reference/commandline/build/#specifying-external-cache-sources
@@ -97,6 +103,8 @@ runs:
           --build-arg BUILD_DATE=${BUILD_DATE} \
           --build-arg GITHUB_SHA=${GITHUB_SHA} \
           \
+          --build-arg ${{ inputs.build_arg }} \
+          \
           --tag ${{ inputs.repository }}/${IMAGE_NAME}:${COMMIT_TAG} \
           --tag docker.io/${IMAGE_NAME}:${COMMIT_TAG} \
           \