Dynamic variables based on environment/context (or anything else!)
_{dynamic-environment is a minimalist choice for switching values based on given conditions in your running app.}

[ Getting started 🤓 | Check it on NPM 👌 ]

Setting it up

Installing it

You can install it from one of these options:

with NPM, Yarn, or PNPM

  $ npm install dynamic-environment

  $ yarn add dynamic-environment
  
  $ pnpm add dynamic-environment

manually

you may also install it as a development dependency in a package.json file:

  // package.json
  "dependencies": {
    "dynamic-environment": "latest"
  }

Then install it with your package manager of choice.

Getting started

Basic usage

import Env from 'dynamic-environment'
import BROWSER from 'dynamic-environment/detectors/browser'
import DOCKER from 'dynamic-environment/detectors/docker'

// Initialize the environment with the contexts of interest
const env = new Env({ BROWSER, DOCKER })

// it will assign 'API_PUBLIC_ENDPOINT` in the browser
// and 'API_CONTAINER_ENDPOINT' in the server
const backendEndpoint = env.pick({
  BROWSER: process.env.API_PUBLIC_ENDPOINT,
  DOCKER: process.env.API_CONTAINER_ENDPOINT,
})

Check the list of available detectors for more options of contexts you can use, or customize your own.

Advanced usage

Require values

Throw an error if the value you need has not been provided

import { demand } from 'dynamic-environment'

// either returns the value or throws `required variable 'API_SECRET' has not been defined`
const API_SECRET = demand(process.env.API_SECRET, 'API_SECRET')

Custom contexts

You can easily write your own context detector. E.g. we can define different commands to be run in different types of machines, as shown below.

import Env from 'dynamic-environment'
import { execaSync } from 'execa'

const env = new Env({
  LINUX: () => process.platform === 'linux',
  MAC: () => process.platform === 'darwin',
})

console.log(env.pick({
  LINUX: `This is what you got, FREE OF CHARGE:`,
  MAC: `This is what you PAID for:`
}))

const osVersion = env.pick({ LINUX: `lsb_release -a`, MAC: `sw_vers` })
execaSync(osVersion, { stdio: 'inherit' })

// This is what you PAID for:
// ProductName:	macOS
// ProductVersion:	12.4
// BuildVersion:	21F79

Env tree and delayed execution

You can put together all your data into one well organized object instead of having multiple variables spread around.

Note: env.tree lazily executes functions inside objects.

const env = new DynamicEnvironment({
  BROWSER,
  SSR,
}).tree({
  uploader: {
    endpoint: env.pick({
      BROWSER: () => demand(process.env.UPLOADER_PUBLIC_ENDPOINT),
      SSR: 'uploader:8080',
    }),
    secret: env.pick({
      BROWSER: () => demand(process.env.UPLOADER_PUBLIC_SECRET),
      SSR: () => demand(process.env.UPLOADER_ADMIN_SECRET),
    }),
  },
})

console.log(
  env.uploader.endpoint, // uploader:8080
  env.uploader.secret // klajsdjDiJjaoasdSJDS
)