Add request ID middleware

backend/src/api/middleware/errors.ts

@@ -1,8 +1,8 @@
 import type { ErrorRequestHandler } from "express";
 import { logger } from "../../logger.js";
 
-export const errorHandler: ErrorRequestHandler = (err, _req, res, _next) => {
-  logger.error(err, "Unhandled error");
+export const errorHandler: ErrorRequestHandler = (err, req, res, _next) => {
+  (req.log ?? logger).error(err, "Unhandled error");
   res.status(err.statusCode ?? 500).json({
     error: err.name ?? "InternalServerError",
     message: err.message ?? "An unexpected error occurred",

backend/src/api/middleware/requestId.ts

@@ -0,0 +1,18 @@
+import { randomUUID } from "crypto";
+import type { Request, Response, NextFunction } from "express";
+import { logger } from "../../logger.js";
+
+declare module "express-serve-static-core" {
+  interface Request {
+    requestId: string;
+    log: typeof logger;
+  }
+}
+
+export function requestId(req: Request, res: Response, next: NextFunction) {
+  const id = randomUUID();
+  req.requestId = id;
+  req.log = logger.child({ requestId: id });
+  res.setHeader("X-Request-ID", id);
+  next();
+}

backend/src/app.ts

@@ -11,6 +11,7 @@ import { yieldsRouter } from "./api/routes/yields.js";
 import { adminRouter } from "./api/routes/admin.js";
 import { webhooksRouter } from "./api/routes/webhooks.js";
 import { errorHandler } from "./api/middleware/errors.js";
+import { requestId } from "./api/middleware/requestId.js";
 import { publicLimiter, authLimiter } from "./api/middleware/rateLimit.js";
 
 export function createApp(): Express {
@@ -26,6 +27,8 @@ export function createApp(): Express {
     app.use(cors({ origin }));
   }
 
+  app.use(requestId);
+
   app.use("/health", publicLimiter, healthRouter);
   app.use("/api/v1/vaults", publicLimiter, vaultsRouter);
   app.use("/api/v1/users", publicLimiter, usersRouter);