type-safe-env

A TypeScript library that provides type-safe environment configuration.

Installation

npm install type-safe-env

Features

• Type Safety: Leverage TypeScript's type system to ensure your environment configurations are correctly typed
• Runtime Validation: Use Zod schemas to validate environment configurations at runtime
• Flexible Path Handling: Support for both string and array path formats
• Error Handling: Built-in error handling with optional debug logging
• Zero Configuration: Simple API that works out of the box

Usage

Basic Example

import { getEnv } from 'type-safe-env';
import { z } from 'zod';

// Define your environment schema using Zod
const envSchema = z.object({
  name: z.string(),
  region: z.string(),
  stage: z.enum(['dev', 'staging', 'prod']),
  instanceCount: z.number().int().positive(),
});

// Load and validate your environment configuration
const checkedEnv = getEnv('path/to/env/file.json', envSchema);

// TypeScript knows the exact shape of checkedEnv
console.log(checkedEnv.name); // string
console.log(checkedEnv.region); // string
console.log(checkedEnv.stage); // 'dev' | 'staging' | 'prod'
console.log(checkedEnv.instanceCount); // number

Using Array Path

You can also provide the path as an array of path segments:

const checkedEnv = getEnv(['path', 'to', 'env', 'file.json'], envSchema);

Using with process.env

const checkedEnv = getEnv('path/to/env/file.json', envSchema);

process.env = {
  ...process.env,
  ...Object.fromEntries(
    Object.entries(checkedEnv).map(([key, value]) => [key, String(value)]),
  ),
};

Using with CDK

// Define your environment schema using Zod
const envSchema = z.object({
  name: z.string(),
  region: z.string(),
  stage: z.enum(['dev', 'staging', 'prod']),
  instanceCount: z.number().int().positive(),
});
const checkedEnv = getEnv('path/to/env/file.json', envSchema);

const stackProps = {
  ...process.env,
  ...Object.fromEntries(
    Object.entries(checkedEnv).map(([key, value]) => [key, String(value)]),
  ),
};

// Use in your CDK stack
new MyStack(app, 'MyStack', stackProps);

Error Handling

The library will throw an error if:

• The environment file cannot be found or read
• The file content doesn't match the provided schema

You can enable debug logging by setting the DEBUG environment variable:

DEBUG=true npm run start

API Reference

getEnv<T>

Loads and validates environment configuration from a file.

Parameters

• pathOfEnvFile: string | Array<string> - Path to the environment file
• envSchema: z.ZodObject<any> - Zod schema for validating the environment configuration

Returns

• z.infer<T> - The validated environment configuration with inferred types from the schema

Throws

• Error - If the file cannot be found or read
• z.ZodError - If the file content doesn't match the provided schema

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for details.

License

This project is licensed under the MIT License - see the LICENSE.md file for details.