Cloudflare Workers

@pydantic/logfire-cf-workers instruments Cloudflare Workers and exports the manual logfire API through the core logfire package.

Install

Terminal

npm install @pydantic/logfire-cf-workers logfire

Enable Node.js compatibility in Wrangler:

wrangler.jsonc

{
  "compatibility_flags": ["nodejs_compat"]
}

For wrangler.toml, use:

wrangler.toml

compatibility_flags = ["nodejs_compat"]

For local development, set a write token in .dev.vars:

.dev.vars

LOGFIRE_TOKEN=your-write-token
LOGFIRE_ENVIRONMENT=development

LOGFIRE_ENVIRONMENT is optional and names the environment on emitted telemetry. For production, store LOGFIRE_TOKEN as a Worker secret:

Terminal

npx wrangler secret put LOGFIRE_TOKEN

In-Process Instrumentation

import * as logfire from 'logfire'
import { instrument } from '@pydantic/logfire-cf-workers'

const handler = {
  async fetch(): Promise<Response> {
    logfire.info('worker request handled')
    return new Response('hello from Logfire')
  },
} satisfies ExportedHandler

export default instrument(handler, {
  service: {
    name: 'checkout-worker',
    namespace: '',
    version: '1.0.0',
  },
})

instrument() is an alias for instrumentInProcess(). It reads LOGFIRE_TOKEN, LOGFIRE_ENVIRONMENT, and LOGFIRE_BASE_URL from the Worker environment.

Tail Workers

The package also supports Cloudflare Tail Worker flows:

• use instrumentTail() in the producer Worker
• use exportTailEventsToLogfire() in the Tail Worker

See examples/cf-producer-worker and examples/cf-tail-worker in this repository for the full wiring.

Vitest

If you test Workers with Vitest, ensure the Workers test pool can optimize the package for module loading:

vitest.config.mts

import { defineWorkersConfig } from '@cloudflare/vitest-pool-workers/config'

export default defineWorkersConfig({
  test: {
    deps: {
      optimizer: {
        ssr: {
          enabled: true,
          include: ['@pydantic/logfire-cf-workers'],
        },
      },
    },
    poolOptions: {
      workers: {
        // Your Workers test configuration.
      },
    },
  },
})

Scrubbing

Pass scrubbing to control sensitive data scrubbing before telemetry is sent:

export default instrument(handler, {
  scrubbing: {
    extraPatterns: ['secret_token'],
  },
  service: {
    name: 'checkout-worker',
    namespace: '',
    version: '1.0.0',
  },
})