Add basic CI to build and test

Use docker compose to build and start the app and then verify that it
started.

.github/workflows/ci.yml

@@ -0,0 +1,22 @@
+name: Build & test
+on: [push]
+jobs:
+  build:
+    name: Build and verify stack
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Setup environment
+        run: |
+          cp .env-example .env
+      - name: Build and start the stack
+        run: |
+          docker-compose up --build -d
+      - name: Verify that the stack is running
+        run: |
+          bash ci-verify.sh
+          if [ $? -ne 0 ]; then
+            docker compose logs
+            exit 1
+          fi
+        shell: bash

ci-verify.sh

@@ -0,0 +1,20 @@
+SUCCESS=0
+
+for try in {1..3}; do
+  status_code=$(curl --write-out %{http_code} --silent --output /dev/null http://localhost:3000)
+  if [[ "$status_code" -eq 200 ]] ; then
+      SUCCESS=1
+      break
+  else
+      echo "Attempt $try failed with status code $status_code"
+  fi
+  sleep 10
+done
+
+if [[ "$SUCCESS" -eq 1 ]] ; then
+    echo "Stack seems to be working 🎉"
+    exit 0
+else
+    echo "Stack is not working 😭"
+    exit 1
+fi