gelf-pro

gelf pro

gelf-pro - Graylog2 client library for Node.js.
Sends logs to Graylog2 server in GELF (Graylog Extended Log Format) format.

Features:

• JS object marshalling
• UDP/TCP/TLS support
• Filtering, Transforming, Broadcasting.

Installation

"dependencies": {
  "gelf-pro": "~1.3" // see the "releases" section
}

npm install gelf-pro (ALL node.js versions are supported [0.x to 2x.x] :)

Library depends on: lodash#~4.17

Initialization

var log = require('gelf-pro');

Adapters

[!WARNING] To ensure consistent behavior, none of the existing adapters re-use the socket connection. Re-using socket connections can lead to resource leakage, complexity in state management, concurrency issues, security risks, and may not always provide significant performance benefits. It's often simpler and safer to establish new connections as needed rather than re-using existing ones, ensuring better resource utilization and reducing potential complications in network communication.

There are multiple (1, 2) variants available for you to borrow from and create a new adapter. See related section.

• UDP (with deflation and chunking)
  • Input: GELF UDP
• TCP
  • Input: GELF TCP (with Null frame delimiter)
• TCP via TLS(SSL)
  • Input: GELF TCP (with Null frame delimiter and Enable TLS)

[!NOTE] Within a more or less stable network (which is most likely), I would recommend using the udp adapter. I would also recommend it for an average to high-loaded project. For sensitive information, the tcp-tls adapter is recommended.

Configuration

// simple
log.setConfig({adapterOptions: {host: 'my.glog-server.net'}});

// advanced
log.setConfig({
  fields: {facility: "example", owner: "Tom (a cat)"}, // optional; default fields for all messages
  filter: [], // optional; filters to discard a message
  transform: [], // optional; transformers for a message
  broadcast: [], // optional; listeners of a message
  levels: {}, // optional; default: see the levels section below
  aliases: {}, // optional; default: see the aliases section below
  adapterName: 'udp', // optional; currently supported "udp", "tcp" and "tcp-tls"; default: udp
  adapterOptions: { // this object is passed to the adapter.connect() method
    // common
    host: '127.0.0.1', // optional; default: 127.0.0.1
    port: 12201, // optional; default: 12201
    // ... and so on
    
    // tcp adapter example
    family: 4, // tcp only; optional; version of IP stack; default: 4
    timeout: 1000, // tcp only; optional; default: 10000 (10 sec)
    
    // udp adapter example
    protocol: 'udp4', // udp only; optional; udp adapter: udp4, udp6; default: udp4
    
    // tcp-tls adapter example
    key: fs.readFileSync('client-key.pem'), // tcp-tls only; optional; only if using the client certificate authentication
    cert: fs.readFileSync('client-cert.pem'), // tcp-tls only; optional; only if using the client certificate authentication
    ca: [fs.readFileSync('server-cert.pem')] // tcp-tls only; optional; only for the self-signed certificate
  }
});

log.setConfig merges the data. Therefore, you can call it multiple times.

Basic functionality

var extra = {tom: 'cat', jerry: 'mouse', others: {spike: 1, tyke: 1}};

log.info("Hello world", extra, function (err, bytesSent) {});
log.info("Hello world", function (err, bytesSent) {});
log.info("Hello world", extra);
log.info("Hello world");

log.error('Oooops.', new Error('An error message'));
// ^-- extra becomes: {short_message: 'Oooops.', _error_message: 'An error message', _error_stack: Error's stack}

log.error(new Error('An error message'));
// ^-- extra becomes: {short_message: 'An error message', full_message: Error's stack}

log.message(new Error('An error message'), 3); // same as previous

Extra

In case extra is a plain object, the library converts it to a readable format. Other values are converted to string. The acceptable format of a key is: ^[\w-]$

log.info(
  'a new msg goes here',
  {me: {fname: 'k', lname: 'k', bdate: new Date(2000, 01, 01)}}
);
// ^-- extra becomes: {_me_fname: 'k', _me_lname: 'k', _me_bdate: 'Tue Feb 01 2000 00:00:00 GMT+0100 (CET)'}

Filtering

Sometimes we have to discard a message which is not suitable for the current environment. It is NOT possible to modify the data.

log.setConfig({
  filter: [
    function (message) { // rejects a "debug" message
      return (message.level < 7);
    }
  ]
});

Transforming

transforming happens after filtering. It is possible to modify the data.

log.setConfig({
  transform: [
    function (message) { // unwind an error
      if (_.isError(message.error)) {
        message.error = {message: message.error.message, stack: message.error.stack};
      }
      return message;
    }
  ]
});

Broadcasting

broadcasting happens after transforming. It is NOT possible to modify the data.

log.setConfig({
  broadcast: [
    function (message) { // broadcasting to console
      console[message.level > 3 ? 'log' : 'error'](message.short_message, message);
    }
  ]
});

Levels (1, 2, 3)

Default:
{emergency: 0, alert: 1, critical: 2, error: 3, warning: 4, notice: 5, info: 6, debug: 7}
Example: log.emergency(...), log.critical(...), etc.
Custom example: {alert: 0, notice: 1, ...}

Third party adapters

You can force using custom adapter by setting the adapter right after initialisation. The signature might be found here.

  var log = require('gelf-pro');
  var myFancyAdapter = require('...');
  log.adapter = myFancyAdapter;
  // (!) adapterName and adapterOptions will be ignored

Aliases

Default: {log: 'debug', warn: 'warning'}
Example: log.log(...) -> log.debug(...), log.warn(...) -> log.warning(...), etc.
Custom example: {red: 'alert', yellow: 'notice', ...}

Tests

Cli

npm install
npm test

Docker

[sudo] docker build --no-cache -t node-gelf-pro .
[sudo] docker run -ti --rm -v "${PWD}:/opt/app" -w "/opt/app" node-gelf-pro

Contributors

• corbinu
• joelharkes
• mkalam-alami

License

MIT