WorkersLogger

An optimized logger for Cloudflare Workers.

This allows you to capture full logs in cloudflare workers (no 150 char line limit) without slowing down your workers or having to setup a HTTP worker for HTTP logpush jobs (to proxy because of their test request).

Used in production at Tangia.

Install

npm i cfworkerslogger

Console Logging

Logging to console (optional) can be done either as JSON or as standard console.x parameter flattening. See the consoleJSON constructor option.

With Meta

An object that will be included in all log.meta lines. You can use this function to provide a common ID to all log lines, for example give all line.meta some common UUID, or attach a RayID.

Anything you provide in the individual log call's .meta will override anything in the options.withMeta object

Usage

// Create a common UUID for all log lines of this run
const logger = new WorkersLogger({
  withMeta: {
    traceID: crypto.uuid()
  }
})

// Add the Cloudflare `RayID` to all log lines
const logger = new WorkersLogger({
  withMeta: {
    RayID: request.headers.get("cf-ray")
  }
})

// Override something in the log line
const logger = new WorkersLogger({
  withMeta: {
    AThing: "a"
  }
})
logger.info("this see a", {
  SomethingEntirelyDifferent: "b"
})
logger.info("this will overwrite", {
  AThing: "c"
})

// Cloudflare log view:
// ["INFO", "this see a", "AThing", "a", "SomethingEntirelyDifferent", "b"]
// ["INFO", "this will overwrite", "AThing", "c"]

With Durable Objects

Durable objects will keep running until all promises have settled, so keep in mind the response won't be delivered until the logger drains. You can do something like:

async fetch() {
  // ... your code
  const res = new Response("wrote events to schema")
  logger.Drain() // DO will wait until all promises have resolved
  return res
}

Destination Function

You may optionally provide a destination function that will bulk-write to a sink. Combined with (event|ctx).waitUntil() you can have this run after the response is written.

Usage

See /examples