Re-add CI and switch back to DigitalOcean

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  docker:
+    name: Docker Build and Push
+    runs-on: ubuntu-latest
+    steps:
+      - 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
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: ekzhang/rustpad:latest
+
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}

README.md

@@ -73,12 +73,15 @@ wasm-pack test rustpad-wasm --chrome --headless
 
 ## Deployment
 
-Rustpad is continuously deployed as a single ~10 MB Docker image, which is built
-automatically from the `Dockerfile` in this repository. We use
-[Google Cloud Build](https://cloud.google.com/build) and
-[Google Cloud Run](https://cloud.google.com/run).
+Rustpad is distributed as a single ~10 MB Docker image, which is built
+automatically from the `Dockerfile` in this repository. You can pull the latest
+version of this image from Docker Hub.
 
-To build and run a Docker image, use the following commands, then open
+```
+docker pull ekzhang/rustpad
+```
+
+To manually build and run a Docker image, use the following commands, then open
 `http://localhost:3030` in your browser.
 
 ```
@@ -88,3 +91,6 @@ docker build -t rustpad .
 ```
 docker run --rm -dp 3030:3030 rustpad
 ```
+
+We deploy a public instance of this image using
+[DigitalOcean App Platform](https://www.digitalocean.com/products/app-platform/).