Better Stack Cloudflare Worker logging

Start logging in 5 minutes

Collect logs from your Cloudflare Workers.

Set up Cloudflare Worker

Either open your existing project with Wrangler CLI if you already have it set up, or initialize new "Hello World" Worker:

wrangler login
wrangler init better-stack-logging-example
cd better-stack-logging-example

Install Better Stack logging library

Install Better Stack logging library for edge JS runtime @logtail/edge:

npm install --save @logtail/edge

Create and use instance of logger

Import and instantiate Logtail class, add the execution context from the request, and use it for your application logs:

import { Logtail } from "@logtail/edge"

export const baseLogger = new Logtail("$SOURCE_TOKEN")

export interface Env {
  // ...
}

export default {{
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    const logger = baseLogger.withExecutionContext(ctx)

    logger.debug("I am using Better Stack!")
    logger.info("An interesting event occurred!")

    // Logging structured data
    logger.warn("Something is not quite right, better check on it.",{
      user:{
        username:"someuser",
        email:"someuser@example.com"
      },
      additional_info:{
        tried_accessing: "/url/of/error"
      }
    })

    // Logging application errors
    function callbackThatMightFail() {
      throw new Error("Example error")
    }
    try {
      callbackThatMightFail()
    } catch (err) {
      logger.error("Oops! An runtime ERROR occurred!", err)
    }

    return new Response('Hello world')
  },
}

Deploy your worker

Deploy your worker using Wrangler CLI

wrangler deploy

Finally, open the worker's URL in your browser to run it.

You should see your logs in Better Stack -> Live tail.

Additional information

• Instantiating the Logtail class outside of fetch handler method will allow different worker runs to share log queue.

• Providing the ExecutionContext instance (usually called ctx) will ensure all logs will be sent to Better Stack. To ensure best results, always use the returned logger instance from Logtail::withExecutionContext() method.

• Want to learn more about log levels and middleware?
  Continue to the Advanced usage of Logtail JavaScript client.

Need help?

Please let us know at hello@betterstack.com.
We're happy to help! 🙏