explicitly listen to all IPv4 interfaces

index.js

@@ -193,6 +193,10 @@ app.get("/api/users/:_id/logs", (req, res) => {
     });
 });
 
-const listener = app.listen(PORT, () => {
-  console.log("Your app is listening on port " + listener.address().port);
+const listener = app.listen(PORT, "0.0.0.0" () => {
+    console.log(
+    `Your app is listening on interface ${
+      listener.address().address
+    } and port ${listener.address().port}`
+  );
 });