@zenvia/logger

Zenvia Logger for Node.js

A wrapper for Winston Logging Node.js library that formats the output on STDOUT as Logstash JSON format.

Installation

npm install @zenvia/logger

Environment Variables

The following environment variables can be used for increase the log information:

• APP_NAME: value to filled the "application" field in the output JSON. If empty, the name attribute on package.json will be used instead.
• NODE_ENV: value to filled the "environment" field in the output JSON.
• HOST or HOSTNAME: value to filled the "host" field in the output JSON.
• LOGGING_LEVEL: set the level of messages that the logger should log. Default to DEBUG.
• LOGGING_FORMATTER_DISABLED (version 1.1.0 and above): When true, the output logging will not be formatted to JSON. Useful during development time. Default to false.

Basic Usage

// ES5
const logger = require('@zenvia/logger');

// ES6 or Typescript
import * as logger from '@zenvia/logger';

logger.info('some message');

Output:

{
  "@timestamp": "2018-06-05T18:20:42.345Z",
  "@version": 1,
  "application": "application-name",
  "message": "some message",
  "level": "INFO"
}

Available logging levels

The log levels are as follows.

• fatal
• error
• warn
• info
• debug

For backward compatibility purposes, "verbose" and "silly" levels will behave the same as "debug" level.

Adding extra key/value fields

logger.debug('Some text message', { keyA: 'value A', keyB: 'value B' });

Output:

{
  "keyA": "value A",
  "keyB": "value B",
  "@timestamp": "2018-06-05T22:04:42.039Z",
  "@version": 1,
  "application": "application-name",
  "message": "Some text message",
  "level": "DEBUG"
}

Logging errors

logger.error('Ops!', new Error('Something goes wrong'));

Output:

{
  "message": "Ops!: Something goes wrong",
  "@timestamp": "2018-06-05T22:14:09.683Z",
  "@version": 1,
  "application": "application-name",
  "level": "ERROR",
  "stack_trace": "Error: Something goes wrong\n    at repl:1:34\n    at Script.runInThisContext (vm.js:91:20)\n    at REPLServer.defaultEval (repl.js:317:29)\n    at bound (domain.js:396:14)\n    at REPLServer.runBound [as eval] (domain.js:409:12)\n    at REPLServer.onLine (repl.js:615:10)\n    at REPLServer.emit (events.js:187:15)\n    at REPLServer.EventEmitter.emit (domain.js:442:20)\n    at REPLServer.Interface._onLine (readline.js:290:10)\n    at REPLServer.Interface._line (readline.js:638:8)"
}

Due to limitations of winston lib, when a text, an error and extra key/value fields are logged at once, the output message field will contain the text message, the error message and the full stack trace as shown.

logger.fatal('Ops!', new Error('Something goes wrong'), { keyA: 'value A', keyB: 'value B' });

Output:

{
  "keyA": "value A",
  "keyB": "value B",
  "@timestamp": "2018-06-05T22:09:22.750Z",
  "@version": 1,
  "application": "application-name",
  "message": "Ops! Error: Something goes wrong\n    at repl:1:34\n    at Script.runInThisContext (vm.js:91:20)\n    at REPLServer.defaultEval (repl.js:317:29)\n    at bound (domain.js:396:14)\n    at REPLServer.runBound [as eval] (domain.js:409:12)\n    at REPLServer.onLine (repl.js:615:10)\n    at REPLServer.emit (events.js:187:15)\n    at REPLServer.EventEmitter.emit (domain.js:442:20)\n    at REPLServer.Interface._onLine (readline.js:290:10)\n    at REPLServer.Interface._line (readline.js:638:8)",
  "level": "FATAL"
}

License

MIT