Config your NodeJS like a Pro!

When I started to develop apps using NodeJS, I wondered, how should I save my configs? It seems that everyone does it in his own way.

The most popular solution - JS files

The most widespread solution is to create a separate js file for each evironment. Each of those js files export an Object containing all the configs for the corresponding environment. This is the method suggested by the popular MEAN.JS and MEAN.IO projects.

Here’s how they do it:

• MEAN.JS
• MEAN.IO

You might wonder, why to use js files for storing configs? Why not just JSON? I think there are 2 reasons for that:

1. Oftenly production configs should get some values from environment variables. It is easy to override some config values from environment variables in a JS file.
2. JSON files are uglier than JS files?!

Node-convict - JSON files

Node-convict tries to solve two problems in the NodeJS configuration area:

• Getting configs from environment variables
• Configs validation

They do it by using a config schema. A config schema is describing

• what should be the structure of the app’s config
• the types of the config values
• names of the environment variables that can override each config value

Having this schema, allows to move the configs to JSON files.

But what if I don’t like JSON files?

I don’t think that JSON files are ugly (XML is). JSON files are cool, and I have nothing against them. However, there is also another language, designed for describing data, which is both cool and beautiful. It is called YAML.

With YAML your config file will look like this:

app:
  name: hello-world
port: 3000
mongo: mongodb://localhost:27017

So how can you use YAML files to store your configs? Unfortunately, Node-convict doesn’t support yaml files currently. However, it is possible to pass an object instead of a file path to convict. Hence, you can get the config object from a YAML file, using some other tools, like the npm package called JS-YAML.

And you’ll have something like this:

var util = require('util');
var fs = require('fs');
var yaml = require('js-yaml');
var convict = require('convict');

var config = convict({
  env: {
    doc: 'The applicaton environment.',
    format: ['production', 'development', 'test'],
    default: 'development',
    env: 'NODE_ENV'
  }
  // other configs
});

// load environment dependent configuration
var env = config.get('env');
var filePath = __dirname + '/env/' + env + '.yml';
var configFile = yaml.safeLoad(fs.readFileSync(filePath));

config.load(configFile);

// Adding the calculated values
config.load({
  envFoo: config.get('env') + 'Foo'
});

// perform validation
config.validate();

module.exports = config;