Action that triggers docker build on push to main.

.github/workflows/build.yml

@@ -0,0 +1,46 @@
+name: Build Docker Images
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    name: Build and push docker images
+    permissions:
+      contents: read
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1
+
+    - name: Setup Docker Metadata
+      id: docker_metadata
+      uses: docker/[email protected]
+      with:
+        images: catalystcoop/pudl-output-differ
+        flavor: latest=auto
+        tags: |
+          type=sha,prefix={{branch}}-
+          type=raw,value=latest-{{branch}}
+    
+    - name: Login to DockerHub
+      uses: docker/login-action@v1
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+    - name: Build and push
+      uses: docker/build-push-action@v2
+      with:
+        context: .
+        push: true
+        tags: ${{ steps.docker_metadata.outputs.tags }}
+        labels: ${{ steps.docker_metadata.outputs.labels }}
+        cache-from: type=gha
+        cache-to: type=gha,mode=max