deepenv

Generates a deeply nested configuration object suitable for backend apps, using environment variables.

Best practice demands that configuration that changes across environments should be contained in the environment rather than in code. This helps with security, managing environments, portability and open-source development.

Unfortunately environment variables are flat string key-value pairs, whereas most apps organise their configuration in deeply nested objects. Environment variable names cannot include a period to indicate nesting.

This means backend developers have to take environment variables such as

MYAPP_MYDATASTORE_CONNECTION_RETRY_INTERVAL=5s

are manually wire them into the configuration object, EG:

const config = 
{
    mydatastore : {
        encoding : 'utf8'
        connection : {
            retry_interval : process.env['MYAPP_MYDATASTORE_CONNECTION_RETRY_INTERVAL']
        }
    },
    myotherconfig : {}
}

deepenv.js automates this process, saving time and enforcing consistency between environment variable names and configuration.

quick start (2 mins)

Install deepenv to a project directory that has been initialised with npm (npm init):

npm i deepenv

Create your application, generating the config using deepenv :

// file: myapp.js
const config = require('deepenv').deepenv() // or ES6: import 'deepenv'; const config = deepenv();
console.log(config)

Run your application using a double-underscored environment variable:

DEEPENV_A__B__C=4 node myapp.js

Observe the generated config

{ a: { b: { c: 4 } } }

deeper demo

Many configuration parameters need not be specified by the environment. These are the first argument to deepenv, so they can be merged with those that are specified by the environment.

The second argument is an object containing options, such as a custom prefix for environment variables that are used by deepenv.

With a double-underscored environment variable:

MYAPP_MYDATASTORE__CONNECTION__RETRY_INTERVAL=5s

And deepenv:

const config = require('deepenv').deepenv(
{   // pre-existing configuration, not mutated by deepenv
    mydatastore : {
        encoding : 'utf8'
    },
    myotherconfig : {}
}, 
{   // deepenv options
    custom_prefix 'MYAPP_'
})

deeply nested config is generated from the environment:

{
    mydatastore : {
        encoding : 'utf8'
        connection : {
            retry_interval : '5s'
        }
    },
    myotherconfig : {}
}

options

custom_prefix : override the default prefix 'DEEPENV_' with one based on the name of your app.

custom_nesting_delimiter : override the default nesting delimiter '__' with something else. Note that environment variable names must consist solely of uppercase letters, digits, and the '_'.

external dependencies

the only external dependency is lodash.set method, not the whole lodash library.

review of similar projects

env2object

allows for deep nesting to be defined in .env files, but does not allow for deep nesting based of generic environment variables given in other way, because dots aren't allowed in environment variable names: https://github.com/doanthuanthanh88/env2object

node-env2object

does allow for environment variable names to specify a nested object, however does not include adequate testing and customisation features: https://github.com/tombburnell/node-env2object

dotenv

popular project that reads from files into the environment, but doesn't help with the next step of going from environment variables into code config, for which manual wiring is still required. https://github.com/motdotla/dotenv