@usvc/component-logger

An application-level logger using Winston under the hood.

Scope

• [x] Application logging with timestamp
• [x] Allows for custom levels (with level filtering) definition
• [x] Allows for assigning an ID to the logger
• [x] Allows for extension of Winston transports
• [x] Allows for extension of Winston formats
• [x] Allows for multiple loggers to exist
• [x] Include FluentD transport for logs centralisation
• [x] Include Zipkin's B3 propagation format into logger (spanId, parentSpanId, traceId, sampled)

Installation

npm i @usvc/component-logger;
# OR
yarn add @usvc/component-logger;

Usage

// es5:
const {logger} = require('@usvc/component-logger');
// es6:
import {logger} from '@usvc/component-logger';

Basic

// require it as per ^
logger.initialize();
logger.info('hi');

Full Configuraiton

// require it as per ^
logger.initialize({
  id: 'logger_id',
  formats: [],
  setPrimary: false,
  levels: {
    rant: 3,
    talk: 2,
    shout: 1,
    scream: 0,
  },
  level: 'rant',
  transports: [logger.createConsoleTransport()],
});
logger.info('hi');

API

The following properties are properties belonging to the imported {logger}. You could also import them as separate functions.

.initialize(:options)

Initialises a logger but does not return it. When running for the first time, this logger will be the default when you do logger.info(...).

To access a logger with an ID 'id', use logger.use('id').info(...).

.initialize takes in an object for the :options with the keys as follows:

Parameters

Key	Defaults To	Description
id	"instance"	Id of the logger
formats	[]	An array of Winston transport formatters
setPrimary	false	Defines whether the logger object should take on keys corresponding to the levels of the newly defined logger
levels	{silly:5000,debug:4000,info:3000,http:2000,warn:1000,error:0}	Levels of the logger
level	"silly"	Level of the logger
transports	[]	An array of Winston transport objects

.createConsoleTransport()

Creates a winston.transports.Console transport object.

Use this transport in the transports property of the .initialize() method.

.createFluentTransport()

Creates a transport object capable of sending logs to a FluentD service. Uses fluent-logger under the hood.

Use this transport in the transports property of the .initialize() method.

Parameters

Key	Defaults To	Description
id	"fluent"	ID of the logger to appear in FluentD
host	"localhost"	Hostname of the FluentD service
port	24224	Port of the FluentD servie
requireAckResponse	false	Determines if we should wait for an ACK by the FluentD service
security	{}	Defines possible security parameters. See below for details
timeout	3.0	Defines the timeout for the FluentD service
tls	false	Determines if TLS should be used
tlsOptions	{}	Options for TLS if tls is true

See https://github.com/fluent/fluent-logger-node#options for more information. We use a subset of their configurations.

.createZipkinContextFormatter()

Creates a formatter which injects the Zipkin context into every log if it is available. Use this formatter in the formats property of the .initialize() method.

Key	Defaults To	Description
loggerId	null	The logger ID to be attached to the log object. REQUIRED
context	null	The context used for the formatter. This needs to be an ExplicitContext.

Examples

Usage with ES5

Goto: Usage with ES5 (requires)

Run: npm run eg:es5 in this directory

Usage with ES6

Goto: Usage with ES6 (imports)

Run: npm run eg:es6 in this directory

Usage with multiple loggers

Goto: Usage with multiple loggers

Run: npm run eg:multiple in this directory

Usage with FluentD logs collector

Docker Compose needs to be installed for this to work

Goto: FluentD example

Run: npm run eg:fluentd in this directory

You can run docker logs -f $(docker ps | grep fluentd | cut -f 1 -d ' ') to get the container ID of the FluentD service, and then run docker logs -f ${CONTAINER_ID} to see the log. It should like: 2018-07-29 07:42:18.000000000 +0000 _test_fluentd: {"message":"hi","level":"info","timestamp":"2018-07-29T07:42:18.360Z"}

Usage with Zipkin context

Docker Compose needs to be installed for this to work

Goto: Zipkin context example

Run: npm run eg:zipkin in this directory

You can go to http://localhost:9411 to see the zipkin trace.

Development

COMING SOON

Changelog

0.0.x

0.0.1

• Initial release

Cheers