@mcf/tracer

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

Scope

• [x] 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

Changelog

0.0.11

• Use cls-hooked for context implementation

0.0.6

• Added static exports for retrieving a Winston formatter to add context details to the logs
• Release!

0.0.5

• Added static exports for retrieving the context provider middleware
• Added static exports for retrieving the Morgan tokenizers

0.0.4

• Added Morgan tokenizer generator

0.0.3

• Initial release