Add basic CI workflow to test action works

Signed-off-by: Nick Adcock <nick.adcock@docker.com>

.github/workflows/main.yml

@@ -0,0 +1,32 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    name: build
+    runs-on: ubuntu-latest
+    steps:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Run local registry
+      run: docker run -d -p 5000:5000 registry:2
+
+    - name: Build and push image
+      uses: ./
+      env:
+        DOCKER_BUILDKIT: 1
+      with:
+        registry: localhost:5000
+        repository: temp/workflow
+        tags: foo
+
+    - name: Remove local image
+      run: docker image rm localhost:5000/temp/workflow:foo
+
+    - name: Run image from registry
+      run: docker run localhost:5000/temp/workflow:foo

Dockerfile

@@ -0,0 +1,3 @@
+FROM alpine:3
+
+ENTRYPOINT ["echo", "docker github actions"]