Copy from https://github.com/actions/hello-world-docker-action

action.yml

@@ -0,0 +1,21 @@
+name: Hello, World!
+description: Greet someone and record the time
+author: GitHub Actions
+
+# Define your inputs here.
+inputs:
+  who-to-greet:
+    description: Who to greet
+    required: true
+    default: World
+
+# Define your outputs here.
+outputs:
+  time:
+    description: The time we greeted you
+
+runs:
+  using: docker
+  image: Dockerfile
+  env:
+    INPUT_WHO_TO_GREET: ${{ inputs.who-to-greet }}