Env-var-to-config-object generator


envigor is a module that creates configuration objects for several modules and backing services based on what environment variables are available.

This is useful for automatically deciding configuration options for twelve-factor apps that run in environments like Heroku, where several different choices of addon can be provisioned to provide the same service: calling envigor will check the environment variables for all known services (and a general set of variables for any services that may be set up manually / in-house), then create a config object that will run that service regardless of provider (envigor objects can usually be passed directly to the setup function of multiple drivers).

Say you're making an Express app with MongoDB, that you're writing for a service like Heroku, with addons like MongoLab to provide your more general services like MongoDB. By using envigor, you can set your app up to find a configured MongoDB service with complete service agnosticism:

npm install --save envigor mongodb
heroku addons:add mongolab


var http = require('http')
var cfg = require('envigor')();
var app = require('./app.js')(cfg);
http.createServer(app).listen(cfg.port || 5000, function() {
  console.log("Listening on " + port);


var express = require('express');
module.exports = function(cfg){
  var app = express();
    if(err) throw err; else app.set('db',db)
  // ...your routes here... 
  return app;

With envigor, the structure of the app server is so common and lightweight that it is provided as a binary with the library named envigorate. Using envigorate, the only scaffolding you need to run an app is, in package.json:

    "start": "envigorate"

(And you can technically leave out that first line if you use index.js instead of app.js.)

The conventional names for the configuration variables queried for are based on the variables and names used by services' Heroku addons, as well as example variable names commonly used in setup documentation and tutorials.

Following this logic, envigor doesn't search for every possible permutation of synonyms and underscores - only the ones it's reasonably likely to encounter based on precedent. If a variable you set isn't getting picked up, check that it's set at the exact name where envigor is looking for it, underscores and all. (Specifically, note that different services place underscores in different places for the same phrases , such as "APIKEY" and "API_KEY".)

Object names are primarily set based on most common phrasing across all instances (such as "username" over "user" or "login"), followed by any additional names used by other popular consumers (such as "user" for SMTP to match the configuration names used by Nodemailer). Specific services will also often have other names set when a common variable name doesn't match the primary name used by envigor.

Configurations that include services define a general configuration hash (such as cfg.redis) in addition to all their services. If no specific values are listed for the general configuration, it will use the first-listed service that is defined in the environment for the definitions of the general configuration, which will also include a .service field with the name of that service.

Default values are provided when part of a service is configured but not the others, like an SMTP service without a hostname. However, objects and defaults are not constructed if no service is specified.


In the root index.js, envigor only adds a few properties:

  • port, the value of the almost-inescapable PORT variable, used for setting the port for a server to listen on
  • ip, the value of the IP variable, used in some environments to specify a specific network interface to listen on
  • database, described in detail in the "database" section below
  • env, the environment variables used to construct the configuration

Every other object in envigor is set by a script in lib/cfg, with a minimal overview described below (read the files themselves for full details as to the environment variables that can give the corresponding values).

Headers for Cross-Origin Resource Sharing. Goes great with ach.

Note that allowOrigin and possibly maxAge are the only CORS configuration parameters that are likely to be deployment-specific, and as such are the only variables you should be setting through the environment / envigor(). While the rest are gathered by envigor, it's mostly for symmetry; they're more likely to be specific to your code, and as such should be ignored / clobbered by static strings when you set up CORS.

cors is also aliased as accessControl.

  • allowOrigin
  • allowCredentials
  • exposeHeaders
  • maxAge
  • allowMethods
  • allowHeaders

Adds: smtp, mandrill, postmark, sendgrid, mailgun

  • username, user, auth.user
  • password, pass, auth.pass
  • hostname, host, server
  • port
  • service

Mandrill by MailChimp

  • username
  • apiKey, password


  • apiKey
  • inboundAddress

SendGrid (http://sendgrid.com)

  • username
  • password

Mailgun: Programmable Mail Servers

  • apiKey
  • smtp
    • username, user, login
    • password, pass
    • hostname, host, server
    • port

Services: mongolab, mongohq (aliased as compose.mongodb)

  • url, uri

Services: rediscloud, redistogo, myredis, openredis, redisgreen

  • url
  • hostname
  • port
  • password
  • database

The individual fields will by default be gathered from url using the form redis://database:password@hostname:port if url is defined: if not, url will be constructed from these fields.

You can also set DEFAULT_REDIS to populate redis with all the default values.

Services: memcachier, memcachedcloud

  • servers, as an array split on semicolons and commas in the defined variable. To reconstruct the string, use servers.join(',').
  • username
  • password

You can also set DEFAULT_MEMCACHE to populate memcache with all the default values.

Services: cleardb

  • url

Services: graphenedb, graphstory

  • url

Services: rabbitmqBigwig, cloudamqp

rabbitmq is also aliased as amqp.

  • url
  • tx.url
  • rx.url
  • hostname, host, server
  • port
  • database, db
  • authKey, auth
  • table
  • url
  • url

Note that, while DATABASE_URL is conventionally used to refer to a PostgreSQL database on Heroku, envigor does not use DATABASE_URL as a fallback name for the PostgreSQL URL. If you wish to have this behavior, add this line after your call to require('envigor')();.

cfg.postgresql = cfg.postgresql || cfg.database;

(Per the note in the section introduction, this is added in index.js.)

The "database" hash, if present, contains the content of env.DATABASE_URL in its url field.

Use of "database" / DATABASE_URL is discouraged, and is included primarily for the use of applications with legacy configuration schemas.

Note that, while DATABASE_URL is conventionally used to refer to a PostgreSQL database on Heroku, envigor does not use DATABASE_URL as a fallback name for the PostgreSQL URL. See the section on postgresql.

RPC interfaces for cryptocurrency daemons patterned after bitcoind

Adds: bitcoin, litecoin, dogecoin

  • hostname, host
  • port
  • username, user
  • password, pass

Amazon Web Services

Adds: aws, s3

  • accessKey
  • secret
  • accessKey, key
  • secret
  • bucket
  • endpoint

Facebook App configuration

  • appId, clientID
  • secret, clientSecret

Reddit App configuration

  • username
  • password
  • appId, clientID, consumerKey, oauth.consumerKey
  • secret, clientSecret, consumerSecret, oauth.consumerSecret

Twitter application OAuth credentials

  • key, consumerKey
  • secret, consumerSecret

The Twilio cloud communications platform

  • accountSid
  • authToken
  • number

reCAPTCHA - http://www.google.com/recaptcha

  • privateKey
  • publicKey