An example Node.js Express application that listens for traces sent to it over a Fastly named log provider that sends data over HTTPS, re-emitting them to an OpenTelemetry collector.
When a Compute application (or VCL service) running on Fastly generates OpenTelemetry traces, it can emit them using the OTLP (OpenTelemetry Protocol) format. Emitting them using Fastly's real-time log streaming is a performant, ideal method for doing this.
Because Fastly named log providers do not currently have direct integration with the OTLP format, this collector proxy can be set up as the receiver for a log provider that sends data over HTTPS. This proxy will, in turn, send those traces to a configured OpenTelemetry collector.
As an HTTPS log provider, this application simply separates these entries at newlines, and, treating each entry as a OTLP JSON-encoded trace, sends them to the OpenTelemetry Collector.
You need Node.js 16.x or newer.
You will need to run this application at an endpoint that is publicly visible, as it will be receiving traces from a program running at your Fastly service.
You will also need an OpenTelemetry collector that will receive the traces that will receive the traces that are re-emitted by this application.
This demo has been tested against the OpenTelemetry Collector Demo.
For testing purposes, you may run it on your local machine and make it publicly available by using a reverse proxy tool such as ngrok.
- Configure the app.
Copy sample.env to .env and make changes. Each key that is not given a
value receives the default value listed below.
| Variable | Description | Default |
|---|---|---|
PORT |
The port at which to run this application | 3001 |
OTEL_HTTP_COLLECTOR_URL |
The trace collection URL of the OpenTelemetry collector | http://localhost:4318/v1/traces |
- Install dependencies.
npm install- Run the application.
npm run startNote that it is not possible to use this proxy to collect traces from an application running under the Fastly local test server.
This is because when named log endpoints are used on the local test server, output is emitted to stdout instead of being sent to an actual log provider.