Add Image healthcheck. (#48)

* add support for `health` argument

* add healthcheck to the image file

Dockerfile

@@ -45,3 +45,5 @@ WORKDIR /app
 USER appuser
 
 ENTRYPOINT ["/tini", "--", "/app/invidious_companion"]
+
+HEALTHCHECK --interval=5s --timeout=5s --start-period=10s --retries=3 CMD ["/tini", "--", "/app/invidious_companion", "healthcheck"]

src/main.ts

@@ -14,10 +14,28 @@ if (Deno.env.get("GET_FETCH_CLIENT_LOCATION")) {
         ) as string;
     }
 }
+
+const args = Deno.args;
+const konfigStore = await konfigLoader();
+const host = Deno.env.get("HOST") || konfigStore.get("server.host") as string;
+const port = Deno.env.get("PORT") || konfigStore.get("server.port") as string;
+
+if (args?.[0] == "healthcheck") {
+    try {
+        const response = await fetch(`http://${host}:${port}/healthz`);
+        if (response.status === 200) {
+            Deno.exit(0);
+        } else {
+            Deno.exit(1);
+        }
+    } catch (_) {
+        Deno.exit(1);
+    }
+}
+
 const { getFetchClient } = await import(getFetchClientLocation);
 
 const app = new Hono();
-const konfigStore = await konfigLoader();
 
 let innertubeClient: Innertube;
 let innertubeClientFetchPlayer = true;
@@ -116,7 +134,6 @@ app.use("*", async (c, next) => {
 routes(app, konfigStore);
 
 Deno.serve({
-    port: Number(Deno.env.get("PORT")) ||
+    port: Number(port),
-        konfigStore.get("server.port") as number,
+    hostname: host,
-    hostname: Deno.env.get("HOST") || konfigStore.get("server.host") as string,
 }, app.fetch);