INSTALL_OTEL_STEP1.md

INSTALLING OPENTELEMETRY STEP 1

AUTO-INSTRUMENTATION

In this step, we will auto-instrument our nodeJS application to collect traces and send all this information directly to the log each component of our application.

Add auto-instrumentation to your code

• In /opentelemetry/src folder, create a tracing.js file with code below

const opentelemetry = require("@opentelemetry/sdk-node");
const { getNodeAutoInstrumentations } = require("@opentelemetry/auto-instrumentations-node");

const sdk = new opentelemetry.NodeSDK({
  traceExporter: new opentelemetry.tracing.ConsoleSpanExporter(),
  instrumentations: [getNodeAutoInstrumentations()]
});

sdk.start()

• Edit docker-compose.yml file to add this tracing.js library to each of our service containers

  • in the volumes section for each nodeJS container (web and service), add the line below

  #volumes:
    - ./opentelemetry/src/tracing.js:/usr/src/app/src/tracing.js:z

• Follow the steps below for each nodejs component, ie /web and /service

  • Update package.json file to add OpenTelemetry dependencies:

  "dependencies": {
    "@opentelemetry/api": "^1.0.4",
    "@opentelemetry/auto-instrumentations-node": "^0.28.0",
    "@opentelemetry/sdk-node": "^0.28.0",
    ...
  }

  • Update the start script to add tracing.js as Requirement
    • edit file nodemon.json and replace node ./src/index.js by

    node --require ./src/tracing.js ./src/index.js
    

Rebuild and test

• Rebuild your application containers with

docker-compose up --build

• Test again your application going to http://localhost:4000 and http://localhost:4000/api/data
  • you should see a json trace file in the logs of each component, like:

      {web              |   traceId: '96c2e7afc176f9ac78c19a5ea37fda35',
      web               |   parentId: 'c0e5186081aa61b2',
      ...
      web               |   status: { code: 0 },
      web               |   events: []
      web               | }