feat: enable configurable trust proxy via TRUST_PROXY environment variable (#202)

Author: giovannibaratta

app/main/src/main.ts

@@ -3,6 +3,7 @@ import {AppModule} from "./app.module"
 import {Logger, LogLevel} from "@nestjs/common"
 import {CustomLogger} from "./logging/custom-logger"
 import {Request, Response, NextFunction} from "express"
+import {NestExpressApplication} from "@nestjs/platform-express"
 
 function isDevOrTestEnv(): boolean {
   return process.env.NODE_ENV === "development" || process.env.NODE_ENV === "test"
@@ -31,7 +32,7 @@ async function bootstrap() {
     logLevels
   })
 
-  const app = await NestFactory.create(AppModule, {logger: logger})
+  const app = await NestFactory.create<NestExpressApplication>(AppModule, {logger: logger})
 
   if (process.env.ENV === "development") {
     Logger.log("Injecting middleware to log OPTIONS requests in development environment.")
@@ -48,6 +49,21 @@ async function bootstrap() {
     credentials: true, // Required for the browser to send/receive cookies and 'Authorization' headers.
     exposedHeaders: ["Location"]
   })
+  const trustProxy = process.env.TRUST_PROXY
+  if (trustProxy !== undefined) {
+    if (trustProxy === "")
+      throw new Error(
+        "TRUST_PROXY environment variable cannot be empty. It must be a valid string, number, or boolean."
+      )
+
+    let parsedValue: string | number | boolean = trustProxy
+    if (trustProxy === "true") parsedValue = true
+    else if (trustProxy === "false") parsedValue = false
+    else if (!isNaN(Number(trustProxy))) parsedValue = Number(trustProxy)
+
+    app.getHttpAdapter().getInstance().set("trust proxy", parsedValue)
+  }
+
   app.enableShutdownHooks()
   await app.listen(3000)
 }