bunyan-stream-elasticsearch

A Bunyan stream for saving logs into Elasticsearch 5.x with custom write function.

V1.0 requires ES6.

Install

npm install bunyan-stream-elasticsearch

Logstash Template

By default bunyan-stream-elasticsearch will create an index with a specific mapping template for your indexPattern. Template name will be template-logstash- with default settings. If your index pattern is for example [test-]YYYY.MM.DD[-pattern] the template name will be template-test--pattern. Each time an instance of this stream is created, the template will be overwritten. You can disable it by passing the option template: false or provide your own via template: {elastic template}.

Custom Write Function

You can add or modify elasticsearch document providing a write(entry) callback option. This allows a fine tuning on how the document will be defined. Do not forget to override the default template if you add new fields.

Example

const bunyan = require('bunyan');
const ElasticsearchStream = require('bunyan-stream-elasticsearch');

const writeCallback = entry => {
   // modify entry values
   entry.myProperty = 'my value';
   return entry;
};

const esStream = new ElasticsearchStream({
  indexPattern: '[logstash-]YYYY.MM.DD',
  type: 'logs',
  host: 'localhost:9200',
  defaultTemplate: true,
  writeCallback,
});

// manage error case
esStream.on('error', err => console.log('Buyan Stream Elasticsearch Error:', err.stack));

// Create the logger itself
const logger = bunyan.createLogger({
  name: "My Application",
  streams: [
    // default stream to console
    { stream: process.stdout },
    // and to Elasticsearch
    { stream: esStream }
  ],
  serializers: bunyan.stdSerializers
});

// start logging
logger.info('Starting application on port %d', app.get('port'));

Options

• client: Elasticsearch client. Defaults to new client created with current set of options as an argument
• type {string|function}: Elasticsearch type field. Default: 'logs'
• indexPattern {string}: Used to generate index if index option not set. Default: '[logstash-]YYYY.MM.DD'
• index {string|function}: Elasticsearch index. Defaults to index generated using index pattern
• template {object|boolean}: Elasticsearch Template to push to elasticseach at each start. If false no template will be pushed, if {...} will act as template replacement.
• writeCallback {function} : Custom write callback to modify the log entry before pushing it to Elasticsearch.

Options type and index can be either a string or function. For these options, when the option is set to a function, the function is passed the log entry object as an argument

Contributors

• Bending Bender

Changelog

2017/10/22

• refactoring in ES6 class format