lazy-config

Lazy Config

Thanks Dane for helping polish the module.

Our team uses this module to lazily evaluate configuration settings, such as environment variables, for our applications.

Install

$ yarn install lazy-config

Ensure that you have a config/default.js and optionally config/{NODE_ENV}.js file for environment overrides

Usage

Lazily evaluate an environment variable

config/default.js

module.exports = {
  isDev: () => process.env.NODE_ENV === 'development',

  db: {
    userName: 'user',
    password: () => {
      return process.env.DB_PASSWORD
    }
  }
}

index.js

const config = require('lazy-config')

// accessing a specific config setting will evaluate the function
console.log('config.db.password', config.db.password)

$ DB_PASSWORD=supersecure node .

// output
$ config.db.password supersecure

Throw when accessing a required environment variable

config/default.js

module.exports = {
  isDev: () => process.env.NODE_ENV === 'development',

  db: {
    userName: 'user',
    password: () => {
      if(!process.env.DB_PASSWORD) {
        throw new Error('Missing environment variable DB_PASSWORD')
      }

      return process.env.DB_PASSWORD
    }
  }
}

index.js

const config = require('lazy-config')

// accessing a specific config setting will evaluate the function
console.log('config.db.password', config.db.password)

// don't set an environment variable
$ node .

// output
$ throws an error complaining about missing DB_PASSWORD