Add a smoke test for the application

.github/workflows/scala.yml

@@ -20,3 +20,7 @@ jobs:
         distribution: 'adopt'
     - name: Run tests
       run: sbt test
+    - name: Smoke test
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: .github/workflows/smoke_test.sh

.github/workflows/smoke_test.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+TRY_COUNT=30
+sbt stage
+
+cd target/universal/stage
+
+APPLICATION_SECRET="9w/DBOjdTE?65hO5IzGu_XL5^AiK^>iUZgIF?mYVUbPNjNU[ver>zw[V@zlbb0wu" access_token=$GITHUB_TOKEN bin/lunatech-blog-engine &
+
+PID=$!
+trap "kill $! 2> /dev/null" EXIT
+
+is_running() {
+  kill -0 $PID 2> /dev/null
+}
+
+is_responding() {
+  curl localhost:9000 -s -o /dev/null
+}
+
+for (( count=0; count < $TRY_COUNT; count++ )); do
+  if ! is_running; then
+    echo "::error::The application stopped before it could serve a page."
+    exit 1
+  fi
+
+  if is_responding; then
+    exit 0
+  fi
+
+  sleep 3
+done
+
+echo "::error::Timeout: the application did not serve a page in time."
+exit 2