@mcf/tracer NPM

`@mcf/tracer`

Creates a Zipkin tracer for consumption by an Express-based application.

Scope

Create a tracer

Installation

npm i @mcf/tracer;
# OR
yarn add @mcf/tracer;

Usage

const {createTracer} = require('@mcf/tracer');
// OR
import {createTracer} from '@mcf/tracer';

Basic

import express from 'express';
import {expressMiddleware} from 'zipkin-instrumentation-express';
import {createTracer} from '@mcf/tracer';
const tracer = createTracer();
const server = express();
server.use(expressMiddleware({tracer}));
server.listen();

// access context from anywhere
import {MCF_TRACE_NAMESPACE} from '@mcf/tracer';
import {getNamespace} from 'cls-hooked';
const namespace = getNamespace(MCF_TRACE_NAMESPACE);
// do whatever you want with namespace

Full Configuration (with defaults)

import express from 'express';
import {expressMiddleware} from 'zipkin-instrumentation-express';
import {createTracer} from '@mcf/tracer';
const tracer = createTracer({
  httpHeaders: {},
  localServiceName: 'unknown',
  sampleRate: 0.5,
  syncIntervalMs: 1000,
  serverHost: 'localhost',
  serverPort: '9411',
  serverProtocol: 'http',
});
const server = express();
server.use(expressMiddleware({tracer}));

API

`.createTracer(:options)`

Creates the tracer instance. The :options parameter has the following schema:

Key	Defaults To	Description	Environment variable
`httpHeaders`	`{}`	Additional HTTP headers to be sent to the Zipkin server	-
`localServiceName`	`os.hostname() OR 'unknown'`	The identity of the current service	process.env.HOSTNAME
`sampleRate`	`0.5`	The frequency of sampling by Zipkin. Settings this to 1.0 may cause your data store behind Zipkin to be populated very quickly. Use higher numbers for testing only	-
`syncIntervalMs`	`1000`	Synchronises the data every X milliseconds	-
`serverHost`	`"localhost"`	The hostname of your Zipkin service	process.env.ZIPKIN_HOST
`serverPort`	`"9411"`	The port on which the Zipkin service is listening to	process.env.ZIPKIN_PORT
`serverProtocol`	`"http"`	The string identifier of the protocol your are using. Typically `"http"` or `"https"`	process.env.ZIPKIN_PROTOCOL