chore: Improve graceful server shutdown (#4625)

* chore: Improve graceful server shutdown

* Replace node timers with custom promise timeout

server/logging/Logger.ts

@@ -28,7 +28,9 @@ class Logger {
   output: winston.Logger;
 
   constructor() {
-    this.output = winston.createLogger();
+    this.output = winston.createLogger({
+      level: isProduction ? "info" : "debug",
+    });
     this.output.add(
       new winston.transports.Console({
         format: isProduction

server/logging/Metrics.ts

@@ -1,5 +1,6 @@
 import ddMetrics from "datadog-metrics";
 import env from "@server/env";
+import ShutdownHelper, { ShutdownOrder } from "@server/utils/ShutdownHelper";
 
 class Metrics {
   enabled = !!env.DD_API_KEY;
@@ -14,6 +15,8 @@ class Metrics {
       prefix: "outline.",
       defaultTags: [`env:${process.env.DD_ENV ?? env.ENVIRONMENT}`],
     });
+
+    ShutdownHelper.add("metrics", ShutdownOrder.last, () => this.flush());
   }
 
   gauge(key: string, value: number, tags?: string[]): void {
@@ -42,6 +45,16 @@ class Metrics {
 
     return ddMetrics.increment(key);
   }
+
+  flush(): Promise<void> {
+    if (!this.enabled) {
+      return Promise.resolve();
+    }
+
+    return new Promise((resolve, reject) => {
+      ddMetrics.flush(resolve, reject);
+    });
+  }
 }
 
 export default new Metrics();