Add healthcheck

Dockerfile

@@ -1,8 +1,15 @@
 FROM node:lts-alpine
 USER node
 WORKDIR /app
-ENV NODE_ENV production
-ENV TZ Europe/Warsaw
+ENV NODE_ENV=production
+ENV TZ=Europe/Warsaw
 COPY --chown=node:node index.mjs ./
 EXPOSE 3000
 CMD ["node", "./index.mjs"]
+
+HEALTHCHECK \
+  --interval=10s \
+  --timeout=5s \
+  --start-period=3s \
+  --retries=3 \
+  CMD ["wget", "http://localhost/health", "-O", "/dev/null", "-q"]

index.mjs

@@ -15,6 +15,11 @@ const server = createServer((req, res) => {
   const host = req.headers['x-forwarded-host'];
   const endpoint = `${req.method} ${req.url}`;
 
+  if (endpoint === 'GET /health') {
+    res.statusCode = 200;
+    return res.end('OK\n');
+  }
+
   console.log(
     `[${dateText}] ${scannerIP} (${userAgent}) targeted ${host} on ${endpoint}`
   );