refactor: migrate from node:http to Express with Express.js tests

src/index.ts

@@ -1,32 +1,23 @@
-import { createServer } from "node:http";
+import express from "express";
 import { hostname } from "node:os";
 import { greeting } from "./greeting.js";
 
+const app = express();
 const port = Number(process.env.PORT ?? 3000);
 const sha = process.env.GIT_SHA ?? "dev";
 
-const server = createServer((req, res) => {
-  if (req.url === "/healthz") {
-    res.writeHead(200, { "content-type": "text/plain" });
-    res.end("ok");
-    return;
-  }
-  res.writeHead(200, { "content-type": "application/json" });
-  res.end(
-    JSON.stringify(
-      {
-        service: "demo-app",
-        message: greeting(),
-        sha,
-        pod: hostname(),
-        time: new Date().toISOString(),
-      },
-      null,
-      2,
-    ) + "\n",
-  );
+app.get("/healthz", (_req, res) => {
+  res.type("text/plain").send("ok");
 });
 
-server.listen(port, () => {
-  console.log(`demo-app ${sha} listening on :${port}`);
+app.get("/", (_req, res) => {
+  res.json({
+    service: "demo-app",
+    message: greeting(),
+    sha,
+    pod: hostname(),
+    time: new Date().toISOString(),
+  });
 });
+
+export { app, port };