Cloudflare Workers And Deno

Use this for edge runtimes that are not ordinary Node.js servers.

Cloudflare Workers

Install:

npm install @pydantic/logfire-cf-workers logfire

Enable Node.js compatibility:

{
  "compatibility_flags": ["nodejs_compat"]
}

For wrangler.toml:

compatibility_flags = ["nodejs_compat"]

Set local development values in .dev.vars. Workers don't auto-read .logfire/logfire_credentials.json the way Python's SDK does, but the token in it is still the one to reuse here rather than minting a new one — see auth.md's "If the calling skill needs a write token" section:

LOGFIRE_TOKEN=your-write-token
LOGFIRE_ENVIRONMENT=development

Store production tokens as Worker secrets, minted separately from Project Settings → Write tokens (a long-lived deployed Worker shouldn't share a credential with your local CLI session):

npx wrangler secret put LOGFIRE_TOKEN

Wrap the exported handler. Import manual spans and logs from logfire.

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

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

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

If wrapping a business function, avoid the name collision by aliasing:

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

Cloudflare export is tied to request lifetime through ctx.waitUntil(). Use ctx.waitUntil() for asynchronous work that should be included in request-lifetime telemetry.

Cloudflare Tail Workers

For Tail Worker flows, use instrumentTail() in the producer Worker and exportTailEventsToLogfire() in the Tail Worker. Follow the SDK examples when wiring producer and tail projects; do not improvise the event shape.

Deno

Deno has built-in OpenTelemetry support. Configure OTLP export to Logfire and use the core package for manual spans. Deno is a generic-OpenTelemetry setup like any non-native-SDK language — for the write token in the header below, reuse what projects use already created rather than minting a new one; see auth.md's "If the calling skill needs a write token" section:

OTEL_DENO=true \
OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=https://logfire-api.pydantic.dev/v1/traces \
OTEL_EXPORTER_OTLP_HEADERS='Authorization=your-write-token' \
deno run --unstable-otel --allow-net main.ts

Manual API:

import * as logfire from 'npm:logfire'

await logfire.span('deno task', {
  attributes: { runtime: 'deno' },
  callback: async () => {
    logfire.info('running deno task')
  },
})

Preserve existing Deno permissions and add only the permissions required by the app and Deno OpenTelemetry configuration.