nconf

Hierarchical node.js configuration with files, environment variables, command-line arguments, and atomic object merging.

Installation

Installing npm (node package manager)

  curl http://npmjs.org/install.sh | sh

Installing nconf

  [sudo] npm install nconf

Getting started

Using nconf is easy; it is designed to be a simple key-value store with support for both local and remote storage. Keys are namespaced and delimited by :. Lets dive right into sample usage:

  var fs    = require('fs'),
      nconf = require('nconf');
  
  //
  // Setup nconf to use the 'file' store and set a couple of values;
  //
  nconf.add('file', { file: 'path/to/your/config.json' });
  nconf.set('database:host', '127.0.0.1');
  nconf.set('database:port', 5984);
  
  //
  // Get the entire database object from nconf. This will output
  // { host: '127.0.0.1', port: 5984 }
  //
  console.dir(nconf.get('database')); 
  
  //
  // Save the configuration object to disk
  //
  nconf.save(function (err) {
    fs.readFile('path/to/your/config.json', function (err, data) {
      console.dir(JSON.parse(data.toString()))
    });
  });

Hierarchical configuration

Configuration management can get complicated very quickly for even trivial applications running in production. nconf addresses this problem by enabling you to setup a hierarchy for different sources of configuration with some sane defaults (in-order):

1. Manually set overrides
2. Command-line arguments
3. Environment variables
4. Any additional user stores (in the order they were added)

The top-level of nconf is an instance of the nconf.Provider abstracts this all for you into a simple API.

nconf.add(name, options)

Adds a new store with the specified name and options. If options.type is not set, then name will be used instead:

  nconf.add('global', { type: 'file', filename: '/path/to/globalconf.json' });
  nconf.add('userconf', { type: 'file', filename: '/path/to/userconf.json' });

nconf.use(name, options)

Similar to nconf.add, except that it can replace an existing store if new options are provided

  //
  // Load a file store onto nconf with the specified settings
  //
  nconf.use('file', { filename: '/path/to/some/config-file.json' });
  
  //
  // Replace the file store with new settings
  //
  nconf.use('file', { filename: 'path/to/a-new/config-file.json' });

nconf.remove(name)

Removes the store with the specified name. The configuration stored at that level will no longer be used for lookup(s).

  nconf.remove('file');

Working with Configuration

nconf will traverse the set of stores that you have setup in-order to ensure that the value in the store of the highest priority is used. For example to setup following sample configuration:

1. Command-line arguments
2. Environment variables
3. User configuration
4. Global configuration

  var nconf = require('nconf');
  
  //
  // Read in command-line arugments and environment variables
  //
  nconf.argv = nconf.env = true;
  
  //
  // Setup the `user` store followed by the `global` store. Note that
  // order is significant in these operations.
  //
  nconf.add('user', { file: 'path/to/user-config.json' });
  nconf.add('global', { file: 'path/to/global-config.json' })

Storage Engines

Memory

A simple in-memory storage engine that stores a nested JSON representation of the configuration. To use this engine, just call .use() with the appropriate arguments. All calls to .get(), .set(), .clear(), .reset() methods are synchronous since we are only dealing with an in-memory object.

  nconf.use('memory');

System

Based on the Memory store, but exposes hooks into manual overrides, command-line arguments, and environment variables (in that order of priority). Every instance of nconf.Provider, including the top-level nconf object itself already has a System store at the top-level, so configuring it only requires setting properties

  //
  // `nconf.get(awesome)` will always return true regardless of 
  // command-line arguments or environment variables.
  //
  nconf.overrides = { awesome: true };
  
  //
  // Can also be an object literal to pass to `optimist`.
  //
  nconf.argv = true;
  
  //
  // Can also be an array of variable names to restrict loading to.
  //
  nconf.env = true;

File

Based on the Memory store, but provides additional methods .save() and .load() which allow you to read your configuration to and from file. As with the Memory store, all method calls are synchronous with the exception of .save() and .load() which take callback functions. It is important to note that setting keys in the File engine will not be persisted to disk until a call to .save() is made.

  nconf.use('file', { file: 'path/to/your/config.json' });

The file store is also extensible for multiple file formats, defaulting to JSON. To use a custom format, simply pass a format object to the .use() method. This object must have .parse() and .stringify() methods just like the native JSON object.

Redis

There is a separate Redis-based store available through nconf-redis. To install and use this store simply:

  $ npm install nconf
  $ npm install nconf-redis

Once installing both nconf and nconf-redis, you must require both modules to use the Redis store:

  var nconf = require('nconf');
  
  //
  // Requiring `nconf-redis` will extend the `nconf`
  // module.
  //
  require('nconf-redis');
  
  nconf.use('redis', { host: 'localhost', port: 6379, ttl: 60 * 60 * 1000 });

More Documentation

There is more documentation available through docco. I haven't gotten around to making a gh-pages branch so in the meantime if you clone the repository you can view the docs:

  open docs/nconf.html

Run Tests

Tests are written in vows and give complete coverage of all APIs and storage engines.

  $ npm test

Author: Charlie Robbins