Cloudflare Setup

The Worker runtime and Durable Object actor runtime both need telemetry in their Effect layers. Both runtimes flush the OTLP exporter after Worker fetches and Durable Object fetch/message/close/error callbacks, so short-lived Worker executions can export the spans they just produced.

The actor runtime has its own runtime, including after hibernation wakeups, so the telemetry layer should be fully provided with FetchHttpClient.layer.

Define telemetry

// api/TelemetryLive.ts
import { Config, Effect, Layer, Redacted } from "effect"
import { FetchHttpClient } from "effect/unstable/http"
import { Otlp } from "effect/unstable/observability"
 
export const telemetryLive = (serviceName: string) =>
  Otlp.layerJson(
    Effect.gen(function* () {
      const token = yield* Config.redacted("OTEL_TOKEN")
      return {
        baseUrl: yield* Config.string("OTEL_EXPORTER_OTLP_ENDPOINT"),
        resource: {
          serviceName,
          attributes: {
            "deployment.environment": "cloudflare",
          },
        },
        headers: {
          authorization: `Bearer ${Redacted.value(token)}`,
        },
        tracerExportInterval: "1 second",
        loggerExportInterval: "1 second",
      }
    }),
  ).pipe(Layer.provide(FetchHttpClient.layer))

If your collector does not require authentication, omit OTEL_TOKEN and headers.

Add telemetry to the Worker prelude

import { telemetryLive } from "./TelemetryLive.ts"
 
export default Worker.make({
  handler: ApiLive.pipe(HttpRouter.toHttpEffect, Effect.flatten),
  prelude: Layer.mergeAll(
    KvLive,
    telemetryLive("tic-tac-toe-worker"),
    TicTacToeNamespace.layer,
    Assets.layer("ASSETS"),
  ),
})

Read Worker Entrypoint for the full Worker file.

Set OTEL_EXPORTER_OTLP_ENDPOINT as a Wrangler var and OTEL_TOKEN as a secret if your collector requires authentication. See Collectors for endpoint, proxy, and credential guidance.

Add telemetry to the actor runtime

The actor runtime does not need a separate tracing wrapper. It runs inside the WorkerdActorRuntime Effect runtime, and its prelude should include telemetry when actor spans and logs should be exported.

prelude: Layer.mergeAll(KvLive, telemetryLive("tic-tac-toe-actor")),

Read Actor Namespace for the namespace/runtime split and Prelude vs Layer for the dependency lifetime split.

Edit on GitHub