node-config-utils

Utility for reading config values from files, command line arguments, and environment variables.

Installation

npm install --save @quantum-sec/node-config-utils

Usage

Create a reusable instance of ConfigService passing a map of configuration options:

// example.config.ts
export const config = new ConfigService({
  'my-option': {
    description: 'An example configuration option',
    required: true,
    alias: 'o',
  },
});

// usage.ts
import { config } from './example.config';

console.log(config['my-option']);

This will now populate the config object with a key my-option taking its value from a CLI argument, environment variable (as MY_OPTION), or from a YAML config file.

Precedence

When a value is specified in multiple mediums, the following order is observed when determining precedence (top of list takes highest precedence):

• CLI arguments
• Environment variables
• Configuration file

Environment Variable Prefix

You can optionally pass an environment variable prefix to the constructor. This is helpful when needing to avoid collisions.

const config = new ConfigService({ /* ... */ }, 'QS');

In the above example QS would be prefixed to each environment variable name. For example, if you define a config key my-option which would normally search the environment variable MY_OPTION, it would instead search QS_MY_OPTION.

Built-In Options

• --help (alias: -h) – display the list of available command line arguments
• --version (alias: -v) – display the version of the application (from package.json)
• --config (alias: -c) – the path to the configuration file (default: ./config.yaml)