Add github build workflow

.github/workflows/main.yml

@@ -0,0 +1,64 @@
+name: CI to Docker Hub
+
+# Controls when the workflow will run
+on:
+  # Triggers the workflow on push or pull request events but only for the master branch
+  push:
+    branches: [ "*" ]
+    tags: [ "*" ]
+  pull_request:
+    branches: [ master ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v2
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+         images: lthub/jupyterhub-api
+         # generate Docker tags based on the following events/attributes
+         tags: |
+           type=schedule
+           type=ref,event=branch
+           type=ref,event=pr
+           type=ref,event=tag
+           type=semver,pattern={{version}}
+           type=semver,pattern={{major}}.{{minor}}
+           type=semver,pattern={{major}}
+           type=sha
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: ./
+          file: ./Dockerfile
+          push: ${{ github.event_name != 'pull_request'  }}
+          tags: ${{ steps.meta.outputs.tags  }}
+          labels: ${{ steps.meta.outputs.labels  }}
+
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}