Type-safe configuration loader for TypeScript

This package helps you:

• define you app config type using classes&decorators
• validate the config according to class property types
• read config values from environment and other sources like .env files
• automatically generate documentation about the app config

How to use

1. Install yarn add configuar
2. Define your application config

import { EnvVariable } from 'configuar';

export default class AppConfig {
  @EnvVariable()
  port: number;

  @EnvVariable()
  dbUrl: string;
}

3. Define the environment using variables or .env file

// .env
PORT=3001
DB_URL=postgres://localhost:5234/postgres

4. Read the configuration

const config = ConfigLoader.getConfig<AppConfig>({ ctor: AppConfig });
/* AppConfig {
  port: 3001,
  dbUrl: `postgres://localhost:5234/postgres`
} */

getConfig throws a validation error, if there are missing variables or wrong value types. 5. Create config schema to share it with your colleagues

npx configuar get-schema ./dist/app-config.ts

You will get:

{
  "type": "object",
  "properties": {
    "PORT": {
      "type": "number"
    },
    "DB_URL": {
      "type": "string"
    }
  },
  "required": ["PORT", "DB_URL"]
}

Put the schema to README.md to explain your colleagues which env variables are required to run the application.

This was just a basic example. You can define nested config objects, use optional params and use it within a Nestjs application.

Docs

• Writing config class
• Reference
• Usage with Nestjs

Further plans

1. Advanced validation: check value formats like Urls, integers etc
2. More decorator options
3. Flexible config schema generator: add human readable config docs generator