Navel Config

Navel Config is a system for parsing configuration files. It was built to suit the requirements of Navel, though it can be used as an independent module for any project.

Installing

You can add this module to your node project with NPM:

npm install --save navel-config

Usage

This section will explain how to use this library.

Basic usage

To load a configuration file you use the module's load method. The load method returns a Future that resolves to a Config instance.

const Config = require('navel-config');
const ROOT_CONFIG_PATH = './config.yml';

Config.load(ROOT_CONFIG_PATH, process.env)
    .fork(console.error, (config) => {
        // config is a Config instance
    })
;

It will also load a remote resource:

const Config = require('navel-config');
const ROOT_CONFIG_URL = 'https://example.com/config.json';

Config.load(ROOT_CONFIG_URL, process.env)
    .fork(console.error, (config) => {
        // config is a Config instance
    })
;

File formats

This module will load files with a .yml, .yaml or .json file extension. Additionally, it will load local files with a .js file extension.

Environment variables

This module will replace any value prefixed with a $ character with a value from the passed in environment.

# config.yml
example:
  var: $EXAMPLE_VAR

const ENV = {EXAMPLE_VAR: 'ok'};
Config.load(pathToConfig, ENV)
    .fork(console.error, (config) => {
        config.get('example/var'); // 'ok'
    })
;

There is also an operator that will achieve the same thing:

# config.yml
example:
  var:
    $env: EXAMPLE_VAR

const ENV = {EXAMPLE_VAR: 'ok'};
Config.load(pathToConfig, ENV)
    .fork(console.error, (config) => {
        config.get('example/var'); // 'ok'
    })
;

You can use a backslash to escape the environment variable:

# config.yml
example:
  var: \$EXAMPLE_VAR

const ENV = {EXAMPLE_VAR: 'ok'};
Config.load(pathToConfig, ENV)
    .fork(console.error, (config) => {
        config.get('example/var'); // '$EXAMPLE_VAR'
    })
;

References

A configuration file can contain a JSON reference. This reference can be a local or remote reference.

# config.yml
example:
  reference:
    $ref: 'https://example.com/config.yml#thing'

# https://example.com/config.yml
thing: value

Config.load(pathToConfig)
    .fork(console.error, (config) => {
        config.get('example/reference'); // 'value'
    })
;

Case Expression

A configuration file may contain a case expression:

# config.yml
example:
  $case:
    of: $color
    cases:
      blue: good
      red: bad
    default: neutral

Config.load(pathToConfig, {color: 'red'})
    .fork(console.error, (config) => {
        config.get('example'); // 'bad'
    })
;

Verbatim

If you want a section of content to be returned without processing, you may use the $verbatim operator.

literal:
  $verbatim:
    $ref: '#/reference'
    $env: 'var'

Config.load(pathToConfig)
    .fork(console.error, (config) => {
        config.get('literal/$ref'); // '#/reference'
    })
;

Running the tests

You can run the project tests with NPM:

npm run lint && npm test

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Authors

• Mark Wardle - Initial work - wardlem

License

This project is licensed under the ISC License - see the LICENSE file for details

Acknowledgments

Forthcoming.