@vicgrk/config

This lib allows you to load yaml files with environement injection for an easy app config management.

Warning: I developped this lib to be included in your source control repository ! This is why you never should sensitive informations (like secrets, API keys, ...) in it and why I included a environment injector.

Install

npm i --save @vicgrk/config

How to use

In the root of your project, create a configs directory.

Basic usage

The simpliest way of using this lib is to create a yml file inside your newly created directory (in my case, I called it basic.yml)

name: My name
foo:
  bar: 0

Now in typescript, you can import your configuration with the loadConfiguration function with the filename of your yaml files :

import { loadConfiguration } from "@vicgrk/config";

interface Configuration {
  name: string;
  foo: {
    bar: number;
  };
}

export const config = loadConfiguration<Configuration>("basic.yml");
console.log(config.name); // expected: My name
console.log(config.foo.bar); // expected: 0

The library is transpiled to es module and CommonJS so you can also use it in javascript no matter your build configuration

// ESM
import { loadConfiguration } from "@vicgrk/config";
export const config = loadConfiguration("basic.yml");

// CommonJS
const { loadConfiguration } = require("@vicgrk/config");
const config = loadConfiguration("basic.yml");
module.exports = config;

You can create config files in subdirectories of your configs folder and import them by pointing the relative path of the config

loadConfiguration("subfolder/config.yml");

Environment Injection

To access sentive data with the type security, we can defined your template with environement variable relations. Let's create a config_with_env.yml file in your configs folder

foo:
  bar: "{{ env.MY_ENVIRONMENT_VARIABLE }}"

Now in typescript:

import { loadConfiguration } from "@vicgrk/config";

interface Configuration {
  foo: {
    bar: string;
  };
}

export const config = loadConfiguration<Configuration>("config_with_env.yml");
console.log(config.foo.bar); // expected to equal the value of process.env.MY_ENVIRONMENT_VARIABLE

You can also populate long strings like DSNs

redis:
  dsn: "redis://{{ env.REDIS_USER }}:{{ env.REDIS_PASSWORD }}@{{ env.REDIS_HOST }}:{{ env.REDIS_PORT }}"

this will return redis://user:password@localhost:6379 with this given environment variables

REDIS_USER=user
REDIS_PASSWORD=password
REDIS_HOST=localhost
REDIS_PORT=6379

You can also provide default values for your environment variables with {{ env.MY_ENVIRONMENT:default_value }}

Current working directory

Weither its trying to look to a sqlite file or a directory where to put uploaded files, applications' config need often to point to filesystem directories or files. I added a cwd() function in the parser to dynamicly inject an absolute path in your application.

Thus the config file :

upload:
  images_folder: "{{ cwd() }}/upload/images"

with this TS file :

import { loadConfiguration } from "@vicgrk/config";

interface Configuration {
  upload: {
    images_folder: string;
  };
}

export const config = loadConfiguration<Configuration>("config.yml");
console.log(config.upload.images_folder); // equal /app/upload/images (if you're running you're process from /app)

prod function

Some configuration does need to be a secret, like client IDs (and NOT client secrets, these are called secrets for a reason) from oauth providers, but varies in developpement or production mode. I've added a prod function in the parser. There are two utilization type :

• The simple prod function {{ prod() }} will return true or false based on the NODE_ENV environment variable is equal to production or prod
• The ternary prod function {{ prod('truthy', 'falsy') }} will return the first (truthy value), or the second argument (falsy value) based on the NODE_ENV environment variable is equal to production or prod

Thus the config file :

isProduction:
  simple: "{{ prod() }}"
  ternary: "{{ prod('this is a true value', 'this is the false value') }}"

with this TS file :

import { loadConfiguration } from "@vicgrk/config";

interface Configuration {
  isProduction: {
    simple: string;
    ternary: string;
  };
}

export const config = loadConfiguration<Configuration>("config.yml");

// if process.env.NODE_ENV === 'dev'
console.log(config); // equal { isProduction: { simple: false, ternary: 'this is the false value' } }

// if process.env.NODE_ENV === 'production' or process.env.NODE_ENV === 'prod'
console.log(config); // equal { isProduction: { simple: true, ternary: 'this is a true value' } }

Type convertion

All string values present in your configuration are converted in numbers, boolean, according to this table

Example value	Parsed type
"TEST"	string
""	string
"233"	number
"233n"	BigNumber
"true"	boolean
"false"	boolean
"null"	null
"undefined"	undefined

.env files

I included a fork of dotenv npm package to include your .env file without any other action. By default, only the .env file is loaded However, you can set other env files to import :

const config = loadConfiguration("config.yml", [
  ".env",
  ".env.dev",
  ".env.prod",
]);

// Or load 0 .env files :
const config = loadConfiguration("config.yml", []);

WARNING: Environment injection is done synchrouslly so it's only loaded once for performance, make sure you load you're file in your global config if you use multiple config files (and thus config variables)