K(con)fg - Simple, Type-Safe Configuration Management

Kfg is a robust and 100% type-safe configuration management system for Node.js and Bun applications. It provides a structured way to define, validate, and access environment variables and other configuration sources with the power of TypeScript.

• ✅ Fully Typed: Autocomplete and type safety for all your configurations.

• ✅ Flexible Drivers: Load configurations from .env files, JSON, or create your own driver.

• ✅ Built-in Validation: Define rules and formats (email, url, etc.) directly in the schema.

• ✅ Smart Defaults: Define defaults that are applied automatically.

• ✅ Nested Structures: Organize your configurations logically.

• ✅ File-based Configuration: Manage configurations across multiple files with Kfg.

• ✅ Relations: Create one-to-one and one-to-many relations between configurations.

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📖 Documentation

• Full Usage Guide: Learn how to install and use Kfg.

Installation

npm install kfg
# or
yarn add kfg
# or
bun add kfg
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Quick Example

1. Define your schema (schema.ts):

import { c } from "kfg";

export const AppSchema = {
  server: {
    host: c.string({ default: "0.0.0.0" }),
    port: c.number({ default: 3000 }),
  },
  database: {
    url: c.string({ prop: "DATABASE_URL" }), // Reads from the DATABASE_URL environment variable
  },
};
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2. Create and load your instance (config.ts):

import { Kfg } from "kfg";
import { envDriver } from "kfg/drivers";
import { AppSchema } from "./schema";

const config = new Kfg(envDriver, AppSchema);
config.load(); // Loads values from .env and process.env

export default config;
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3. Use it anywhere (index.ts):

import config from "./config";

const port = config.get("server.port"); // Inferred as `number`
const dbUrl = config.get("database.url"); // Inferred as `string`

console.log(`Server running on port ${port}`);

// Type Error! TypeScript prevents incorrect assignments.
// config.set("server.port", "not-a-number");
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File-based Configuration with Kfg

Kfg allows you to manage configurations across multiple files, which is useful for managing configurations for different users, tenants, or environments.

1. Define your schemas:

import { Kfg, c, cfs, jsonDriver } from "kfg";

const inventory = new Kfg(jsonDriver, {
    items: c.array(c.string()),
});

const user = new Kfg(jsonDriver, {
    name: c.string(),
    inventory_ids: cfs.many(inventory),
});
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2. Initialize Kfg:

inventory.init((id) => `resources/inventory/${id}.json`);
user.init((id) => `resources/users/${id}.json`);
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3. Use it:

const user1 = user.file("user-1");
user1.set("name", "Alice");

const inv1 = inventory.file("inv-1");
inv1.set("items", ["sword", "shield"]);

user1.set("inventory_ids", [inv1]);

const user1Inventories = await user1.getMany("inventory_ids");
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License

MIT