lib-config

Lets you define your config as ordinary code files The name of the file, maps to the name of the APP_ENV

Philosophy

The philosophy (summarised in confluence) is that ENV vars should be used only for secret config.

For other non-secret settings that vary between environments (eg. the API url, which might be test-api.com or api.com), it's easier to manage them in hard-coded config files. A single environment variable called APP_ENV determines what environment we're running in (development, test, production, etc) and the relevant config file is loaded based on that.

APP_ENV values

APP_ENV can be whatever you want. At Luxury Escapes, we typically use:

development
spec (for running automated tests - both in CI and locally
test (aka staging - but we've called it test in enough places that changing now is hard)
production

For javascript

// config/production.js (e.g. APP_ENV=production)

module.exports = {
  port: parseInt(process.env.PORT || ''),
  apiEndpoint: 'https://myprodapi.com'
}

For typescript

// config/production.ts (e.g. APP_ENV=production)

export const config = {
  port: parseInt(process.env.PORT || ''),
  apiEndpoint: 'https://myprodapi.com'
}

in your start up file you would have something like this

const config = require('@luxuryescapes/lib-config')
config.load({
  env: 'local', // optional, defaults to process.env.APP_ENV,
  schema: {
    // json schema of the config schema
    type: 'object',
    properties: {
      port: { type: 'integer' },
      apiEndpoint: { type: 'string' }
    },
    required: ['port', 'apiEndpoint'],
    additionalProperties: false
  },
  configDir: 'myconfig' // optional, default to `config`
})

then in other files you can do the following

const config = require('@luxuryescapes/lib-config')

express.listen(config.get().port)

get your test runner to load config as the first step

process.env.APP_ENV = 'spec'
const config = require('@luxuryescapes/lib-config')
config.load()

or

const config = require('@luxuryescapes/lib-config')
config.load({ env: 'spec' })

if you want to mock config for unit testing you can do something like this

const sinon = require('sinon')
const config = require('@luxuryescapes/lib-config')

beforeEach(() => {
  sinon.sandbox(config, 'get').returns({
    ...config.get(),
    myFeatureEnabled: false
  })
})

afterEach(() => {
  sinon.sandbox.restore()
})