Add healthcheck script

docker/build.dockerfile

@@ -14,6 +14,7 @@ FROM node:lts-alpine as runtime-image
 WORKDIR /root/app
 
 COPY ./package.json ./
+COPY ./scripts/healthcheck.js ./
 
 RUN npm i --only=production
 

scripts/healthcheck.js

@@ -0,0 +1,20 @@
+(async () => {
+    const http = await import('http');
+
+    const healthCheck = http.request("http://localhost:8080/healthcheck", (res) => {
+        console.log(`HEALTHCHECK STATUS: ${res.statusCode}`);
+        if (res.statusCode == 200) {
+            process.exit(0);
+        }
+        else {
+            process.exit(1);
+        }
+    });
+
+    healthCheck.on('error', function (err) {
+        console.error('ERROR');
+        process.exit(1);
+    });
+
+    healthCheck.end();
+})();