Request-scoped logger

[fr3fou]

Motivation

pinojs' child loggers are incredibly useful in the context of request-scoped logging. They allow you to provide extra information with every subsequent log that uses the same logger.

One example of this is to attach a requestId field to a child logger in a middleware before every request and then have each log automatically "inherit" the same requestId. This allows for easy debugging by filtering all relevant logs by the same requestId. This way you can see all your debug / info / error logs and see the entire trace of a user action. Another example would be to attach userId or tenantId.

Problem

Unfortunately, Payload doesn't allow a way to override the logger for a single request. Your middleware would have to override the req.payload.logger field which (due to the singleton nature of Payload) will override the logger for every concurrent request.

A workaround would involve:

1. Using custom fields on the req object
2. Using AsyncLocalStorage

export const requestIdStorage = new AsyncLocalStorage()

export const enrichRequest = (req: PayloadRequest, res: Response, next: NextFunction) => {
  const existingID = req.headers["x-request-id"]
  const id = existingID && existingID !== "" ? existingID : crypto.randomUUID()
  res.setHeader("X-Request-Id", id)
  res["startTime"] = res["startTime"] || Date.now()
  requestIdStorage.run(id, () => {
    next()
  })
}

export const getLogger = (req: PayloadRequest) => {
  const requestId = requestIdStorage.getStore()
  return req.payload.logger.child({ reqId: requestId })
}

This works for logs that the end user of Payload might be making, but it doesn't handle any logs that Payload itself (or any plugin for that matter) might be making. For example, Payload provides a built in errorHandler middleware:

payload/packages/payload/src/initHTTP.ts

Lines 87 to 88 in 8104fac

	payload.errorHandler = errorHandler(payload.config, payload.logger)
	payload.router.use(payload.errorHandler)

If you want to trace an error log all the way back to the initial HTTP request that caused it, you wouldn't be able to, as that doesn't use your custom child logger.

Solutions

There're 2 solutions that come to mind:

• Expose the ability to create child loggers using the Payload config – some kind of getLogger(req: PayloadRequest): pino.Logger function that would then be called by Payload on every request instead of using the base logger
• Automatically generate and provide requestId to every log – this wouldn't cover all use cases but it'd be good enough