Server error and endpoint metrics

Summary: Better than using logs.

Reviewed By: antonk52

Differential Revision: D50012506

fbshipit-source-id: 2f0e9bf8cb7282d35dc5619e620d005b96663fd5

desktop/flipper-server-core/src/server/startServer.tsx

@@ -152,11 +152,12 @@ async function startHTTPServer(
   });
 
   app.get('/ready', (_req, res) => {
+    tracker.track('server-endpoint-hit', {name: 'ready'});
     res.json({isReady});
   });
 
   app.get('/info', (_req, res) => {
-    console.info('[flipper-server] Received info request');
+    tracker.track('server-endpoint-hit', {name: 'info'});
     res.json(environmentInfo);
   });
 
@@ -164,6 +165,7 @@ async function startHTTPServer(
     console.info(
       '[flipper-server] Received shutdown request, process will terminate',
     );
+    tracker.track('server-endpoint-hit', {name: 'shutdown'});
     res.json({success: true});
 
     // Just exit the process, this will trigger the shutdown hooks.
@@ -171,6 +173,7 @@ async function startHTTPServer(
   });
 
   app.get('/health', (_req, res) => {
+    tracker.track('server-endpoint-hit', {name: 'health'});
     res.end('flipper-ok');
   });
 
@@ -186,6 +189,8 @@ async function startHTTPServer(
 
   server.on('error', (e: NodeJS.ErrnoException) => {
     console.warn('[flipper-server] HTTP server error: ', e.code);
+    tracker.track('server-error', {code: e.code, message: e.message});
+
     if (e.code === 'EADDRINUSE') {
       console.warn(
         `[flipper-server] Unable to listen at port: ${config.port}, is already in use`,

desktop/flipper-server-core/src/tracker.tsx

@@ -39,6 +39,8 @@ type ServerBootstrapPerformancePayload = {
 type TrackerEvents = {
   'server-bootstrap-performance': ServerBootstrapPerformancePayload;
   'server-started': {port: number};
+  'server-error': {code: string | undefined; message: string};
+  'server-endpoint-hit': {name: string};
   'server-auth-token-verification': {
     successful: boolean;
     present: boolean;