Backend Recorder Launcher

Downloads the backend-recorder bundle script and executes it. The backend recorder intercepts HTTP requests/responses in Node.js apps using OpenTelemetry and exports spans to Meticulous.

Setup

npm install @alwaysmeticulous/backend-recorder-launcher

Option 1: Using instrumentation.js (recommended)

Create or update your instrumentation.js (or instrumentation.ts) file at the root of your project:

const {
  initBackendRecorder,
} = require("@alwaysmeticulous/backend-recorder-launcher");

initBackendRecorder({
  recordingToken: process.env.METICULOUS_RECORDING_TOKEN,
});

Then start your app with the --require flag so the recorder is loaded before your application code:

node --require ./instrumentation.js app.js

If you are using Next.js, add the instrumentation hook in instrumentation.ts:

export async function register() {
  if (process.env.NEXT_RUNTIME === "nodejs") {
    const { initBackendRecorder } =
      await import("@alwaysmeticulous/backend-recorder-launcher");
    await initBackendRecorder({
      recordingToken: process.env.METICULOUS_RECORDING_TOKEN,
    });
  }
}

Option 2: Auto-init (zero-code)

Use the auto-init entry point which initializes the recorder as a side effect. No code changes needed — just add the --require flag:

node --require @alwaysmeticulous/backend-recorder-launcher/auto-init app.js

The auto-init entry point reads configuration from environment variables.

Configuration

initBackendRecorder accepts an optional BackendRecorderConfig object:

Redacting recorded backend data

Use spanRedactionHooks to replace sensitive values before completed spans are saved or uploaded. Each hook receives every redactable string and must return a string. Hooks run in the order they are provided.

await initBackendRecorder({
  recordingToken: process.env.METICULOUS_RECORDING_TOKEN,
  spanRedactionHooks: [
    (value) =>
      value.replace(/api_key=[A-Za-z0-9_-]+/g, "api_key=[REDACTED_API_KEY]"),
  ],
});

The hooks cover span names, error/status messages, and all span attribute values, including strings inside arrays or objects and JSON captured inside strings. They do not transform attribute names, trace/span/parent IDs, timestamps, span kind, client-technology routing, or frontend session IDs.

Hooks run only while recording. If a hook throws or returns a non-string, Meticulous abandons the recording rather than saving the span without redaction. Replacing backend-generated request data can also change a replay match key; use stable replacements and verify that the corresponding input will have the same value during replay. This programmatic option applies to the Node.js recorder and is not available to the Cloudflare Workers sidecar.

Graceful shutdown

initBackendRecorder returns a BackendRecorderHandle with a stopRecording() method. Call it before your process exits to flush any pending spans:

const handle = await initBackendRecorder({
  /* ... */
});

process.on("SIGTERM", async () => {
  await handle?.stopRecording();
  process.exit(0);
});