ctrl-env

An alternative way to assert environment variables.

Installation

Yarn is recommended for installation.

$ yarn add ctrl-env

But you can still use npm:

$ npm install --save ctrl-env

Usage

// Example app.js:

const CtrlEnv = require('ctrl-env')

const ctrlEnv = new CtrlEnv([
  ['SECRET']
, ['PORT', {required: false}]
], {
  prefix: 'TWITTER_FEED'
})

ctrlEnv.assert()

// Some Twitter Feed and Server pseudo code:

http.on('/feed', (request, response) => {
  Twitter.getFeed({
    handle: '_experiments'
  , secret: ctrlEnv.SECRET
  }, (error, feed) => {
    if (error) {
      throw error
    }

    response.send(feed)
  })
})

http.listen(ctrlEnv.PORT)

$ TWITTER_FEED_SECRET='twitter_secret_key' TWITTER_FEED_PORT=8080 node app.js
$ # or
$ TWITTER_FEED_SECRET='twitter_secret_key' node app.js

Methods v2

constructor(Array environmentVariables, Object options)

The constructor takes an array of environment variables to expect. The variables themselves can be configured:

const exampleEnvVars = [
  // Variable is required and can be any value:
  ['REQUIRED_VARIABLE']

  // Variable is optional and can be any value:
, ['OPTIONAL_VARIABLE', {required: false}]

  // Variable is required and can only be yes or no:
, ['LIMITED_VARIABLE', {values: ['yes', 'no']}]

  // Variable is required and can only be an integer:
, ['TYPED_VARIABLE', {type: 'integer'}]

  // Variable is optional and can only be yes or no:
, ['OPTIONAL_LIMITED_VARIABLE', {required: false, values: ['yes', 'no']}]

  // Variable is required but is not prefixed:
, ['NODE_ENV', {prefixed: false}]
]

const ctrlEnv = new CtrlEnv(exampleEnvVars)

The constructor also takes an optional prefix and separator. The separator only determines what seperates the prefix and the variable name:

// Variables must be labeled TEST_(VARIABLENAME):
new CtrlEnv(..., {prefix: 'TEST'})

// Variables must be labeled TEST___(VARIABLENAME)
new CtrlEnv(..., {prefix: 'TEST', separator: '___'})

ctrlEnv.assert()

This method actually reads the environment variables and asserts that they exist or have the required values. Note: This method is synchronous.

get ctrlEnv.VARIABLE_NAME

To read the environment variable, simply use the variable name without the prefix as a property of your CtrlEnv instance. This property is a proper ES2015 getter that does not have a setter. It cannot be overwritten without using Object.defineProperty.

get ctrlEnv.all

This returns an object with all asserted environment variables. This property is a propert ES2015 getter that does not have a setter. It cannot be overwritten without Object.defineProperty.

Note: This deprecates #get() from v1.

License

Copyright (c) 2017 Martin Experiments LLC

MIT (https://www.opensource.org/licenses/MIT)