feat: add health check server

src/server/serve.ts

@@ -0,0 +1,48 @@
+import { readFile } from "fs/promises";
+
+import { type Client, WebhookClient } from "discord.js";
+import fastify from "fastify";
+
+import { errorHandler } from "../utils/errorHandler";
+
+/**
+ * Starts up a web server for health monitoring.
+ *
+ * @param {Client} bot The bot's Discord instance.
+ */
+export const instantiateServer = async (bot: Client) => {
+  try {
+    const server = fastify({
+      logger: false,
+      https: {
+        cert: await readFile(
+          "/etc/letsencrypt/live/oogie.nhcarrigan.com-0001/cert.pem"
+        ),
+        key: await readFile(
+          "/etc/letsencrypt/live/oogie.nhcarrigan.com-0001/privkey.pem"
+        ),
+      },
+    });
+
+    server.get("/", (_req, res) => {
+      res.send("Health check~!");
+    });
+
+    server.listen({ port: 1443 }, (err) => {
+      if (err) {
+        void errorHandler("start server", err);
+        return;
+      }
+      const hook = new WebhookClient({ url: process.env.DEBUG_HOOK as string });
+      void hook.send({
+        avatarURL:
+          bot.user?.displayAvatarURL() ??
+          "https://cdn.nhcarrigan.com/profile.png",
+        content: "Fastify server live on port 1443~!",
+        username: bot.user?.username ?? "Hacktoberfest",
+      });
+    });
+  } catch (err) {
+    await errorHandler("instantiate server", err);
+  }
+};