Manage environment stuff with YAML.

npm install --save yenv

Requires node v4.x or above.

Declaring variables in a file (eg. env.yaml):

# Development-specific settings.
development:
  PORT: 3000
  DROP_DATABASE: true
# Production-specific settings.
production:
  PORT: 80
  DROP_DATABASE: false

Reading the file:

const yenv = require('yenv');

// Default filename is env.yaml.
const env = yenv();

// You can call it with a filename, too.
const env = yenv('env.yaml');

// The top-level element in the YAML-file is used to
// read the correct set of variables. The value is grabbed
// from `process.env.NODE_ENV`. To explicitly specify it, use:
const env = yenv('env.yaml', { env: 'production' });

console.log(env.PORT);
console.log(env.DROP_DATABASE);

When a variable is defined in the environment, it will take precedence over whatever was defined in the yaml-file. This means that if your hosting provider (Heroku, Azure, whatever...) sets the PORT variable, then that's the variable that will be used.

Sensitive configuration should always be defined in the actual environment variables and not committed to source control!

yenv supports composing sections together. This is best illustrated with a code example.

# Some base config..
base:
  SOME_URL: 'http://google.com'

# Another section, related to the web config..
web:
  PORT: 1338

# Development config uses base config
development:
  # We can compose more than one at a time.
  ~compose: [base, web]
  # Declare additional settings..
  DEV_MODE: true

# Production config composes and overrides other sections
production:
  ~compose: development
  PORT: 80
  DEV_MODE: false

yenv supports importing files recursively, with the importer winning in case of duplicate variables. Paths are resolved relative to the importing file!

database.yaml

development:
  DB_HOST: localhost

web.yaml

development:
  PORT: 1337
production:
  PORT: 80

env.yaml

~import: [database.yaml, web.yaml]
development:
  PORT: 3000 # This wins over web.yaml because this is the importer.

const env = yenv();
env.DB_HOST; // "localhost"
env.PORT; // 3000

As mentioned earlier, in case of clashes the importer always wins. However, when it comes to 2 files being imported, the last one specified wins (but still not over the importer).

ProTip: You can use ~compose on sections defined in imported files. Example:

stuff.yaml

cool-section:
  STUFF: 'yenv is the best'

env.yaml

~import: stuff.yaml
development:
  ~compose: cool-section

Typings are available in lib/yenv.d.ts and are set in package.json.

To import yenv in TypeScript:

import * as yenv from 'yenv';

Please see CHANGELOG.md.

Jeff Hansen - @Jeffijoe