varium

Varium

Varium is a library and syntax for managing environment variables in a sane way. You should use it if you want to:

• declare all used environment variables in one place
• specify which types they have
• validate that they are of the right type
• cast environment variables to the right type when used
• require certain variables
• default to a value for other variables
• abort CI if variables are missing or fail validation
• warn developers if they use an undeclared environment variable

Installation

npm install varium --save

Requires node v6.5 or above.

Usage example

Create a file called env.manifest in the project root. It should contain all environment variables used in the project. For example:

API_BASE_URL : String
API_SECRET : String

# This is a comment
# The following is an optional variable (the above were required):
NUMBER_OF_ITEMS : Int |

FLAG : Bool | False # Variables can also have default values. Here it is False
COMPLEX_VALUE : Json | [{ "object": 42 }] # Use json for advanced data structures

QUOTED_STRING : String | "Quote the string if it contains # or \\escaped chars"

Then create the file which all your other files imports to obtain the config. For example config/index.js. This needs to at least contain:

const varium = require('varium');

module.exports = varium();

Import this file in the rest of your project to read environment variables:

const config = require('../config');
const url = config.API_BASE_URL;

// An error will be thrown if you try to load an undeclared variable:
const wrong = config.API_BASE_ULR;
// -> Error('Varium: Undeclared env var "API_BASE_ULR.\nMaybe you meant API_BASE_URL?"')

To prevent other developers or your future self from using process.env directly, use the no-process-env eslint rule.

Your environment now needs to contain the required variables. If you use a library to load .env files (such as node-forman or dotenv), the .env could contain this:

API_BASE_URL=https://example.com/
API_SECRET=1337
NUMBER_OF_ITEMS=3

To abort builds during CI when environment variables are missing, just run the config file during th build step. For example, on heroku the following would be enough:

{
  "scripts": {
    "heroku-postbuild": "node ./config"
  }
}

For a complete syntax and api reference (for example how to add your own custom types), see the docs.