Jaeger Client Middleware for NodeJS

A middleware for NodeJS support jaeger-client-nodejs

NodeJS 10.x recommended

npm i jaeger-client-middleware

Before Setup

This package is a middleware version of jaeger-client-nodejs, without jaeger setup this package has no effect. Please read these references:

• Ref:

  -- jaeger-client for NodeJS https://github.com/jaegertracing/jaeger-client-node

  -- jaeger tracing for local run https://www.jaegertracing.io/docs/1.16/getting-started

  -- jaeger tracing for production https://www.jaegertracing.io/docs/1.16/deployment

How to use

1. Create jeager.js file on your project (libs directory recommended)

libs/jaeger.js

const { initTracer } = require('jaeger-client');

const config = {
  serviceName: 'your-service-name': String,
  reporter: {
    name: 'your-service-name-reporter' : String,
    logSpans: true,
    agentHost: 'your-reporter-host': String,
    agentPort: 'your-report-port': Number
  },
  sampler: {
    type: 'your-sampler-type',
    param: 1.0
  }
};

const options = {
  tags: {
    'service': 'your-service-tag': String,
    'version': 'your-service-version': String,
  }
}
module.exports = initTracer(config,options);

example:

import { initTracer } from "jaeger-client";

const config = {
  serviceName: "my-service",
  reporter: {
    name: "my-service-reporter",
    logSpans: true,
    agentHost: process.env.JAEGER_AGENT_HOST || "localhost",
    agentPort: process.env.JAEGER_AGENT_PORT || 6832
  },
  sampler: {
    type: "const",
    param: 1.0
  }
};
const options = {
  tags: {
    service: "my-service",
    version: process.env.npm_package_version || "1.0.0"
  }
};

export default initTracer(config, options);

2. Create Middleware file (middlewares directory recommended)

middlewares/jaeger-middleware.js

const jaeger = require("path-to-libs/jaeger.js");
const JaegerMiddleware = require("jaeger-client-middleware");
const jaegerMiddleware = new JaegerMiddleware(jaeger);
module.exports = jaegerMiddleware;

After created, your structure should look like

├── libs
│   └── jaeger.js
├── middlewares
│   └── jaeger-middleware.js
├── package.json
├── routes
│   └── index.js
├── app.js

3. Use for API

app.js

const jaegerMiddleware = require("path-to-middleware/jaeger-middleware.js");

// assume you are using express
const app = require('express')();
app.use(
  jaegerMiddleware.handleLogBeforeResponse,
  jaegerMiddleware.createSpanAfterReceivedRequest
);

4. Inject request header before sending request

const jaegerMiddleware = require("path-to-middleware/jaeger-middleware.js");
const injectedHeader = jaegerMiddleware.buildHeaderForHTTPRequest(yourHeaderObject)
// now use injected header for your request