add github actions

.github/workflows/build-and-push.yaml

@@ -0,0 +1,42 @@
+name: ci
+
+on:
+  push:
+    tags: 
+    - "*"
+
+jobs:
+  path-context:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
+      -
+        name: Docker meta
+        id: docker_meta
+        uses: crazy-max/ghaction-docker-meta@v1
+        with:
+          images: dodasts/jhub # list of Docker images to use as base name for tags
+          tag-sha: true # add git short SHA as Docker tag
+      -
+        name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      -
+        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: ./docker/jupyter-hub
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm64,linux/386
+          push: true
+          tags: ${{ steps.docker_meta.outputs.tags }}