README.md

Node.js in Docker

The following example demonstrates how you can add otelify.sh to an existing containerized application, without changing the code of that application.

Before getting started, verify that you can run the application without instrumentation using docker and docker compose:

docker compose up 

This will start a Node.js application that you can connect to via HTTP on port 8080:

$ curl localhost:8080
Hello world!

To instrument this application, update the docker-compose.yml as follows:

version: "3"

services:
  app:
    image: otelify/nodejs-http-server
    build: .
    ports:
      - 8080:8080
    ### add otelify.sh via a mount and change entrypoint and command
    ### to wrap it around the application
    volumes:
     - ../../otelify.sh:/usr/bin/otelify.sh
    entrypoint: /usr/bin/otelify.sh
    command: ["app.js"]
    environment:
     - OTEL_TRACES_EXPORTER=otlp
     - OTEL_EXPORTER_OTLP_ENDPOINT=http://otel-collector:4318
     - OTEL_NODE_RESOURCE_DETECTORS=env,host,os,process,serviceinstance
     - OTEL_NODE_DISABLED_INSTRUMENTATIONS=fs

  # add an OpenTelemetry collector 
  otel-collector:
    image: otel/opentelemetry-collector
    volumes:
    - ./otel-collector-config.yaml:/etc/otelcol/config.yaml
    ports:
      - 4317:4317
      - 4318:4318

Next, re-run docker compose up. It will take a little longer to get the app (and the collector) up and running, since the Node.js packages will be downloaded at runtime. When you see the message listening on port 8080 printed, run curl localhost:8080 once again. After a few seconds the OpenTelemetry Collector will output detailed trace information.