@alaan/s2s-auth/README.md

Reusable JWT auth module for NestJS service-to-service authentication

# @alaan/s2s-auth

A lightweight NestJS library for service-to-service authentication using JWT (JSON Web Tokens).

## Features

- Secure JWT-based authentication between microservices
- Customizable payload and expiration

## Installation

```bash
npm install @alaan/s2s-auth
```

## Usage

### 1. Initialize the S2SAuthModule

```ts
@Module({
  imports: [S2SAuthModule.forRoot({secret:"secret-key", expiresIn: '1m'})],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}
```

### 2. Add the Auth Guard to a controller

```ts
  @Get()
  @UseGuards(S2SJwtAuthGuard)
  getHello(): string {
    return this.appService.getHello();
  }
```

### 3. Generate the token through shared secret or a trusted Idp

```ts
s2sAuthService.createToken({serviceId: 'test-service', scope: 'read'});
```

## Configuration

- `secret`: JWT signing/verification secret (required)
- `expiresIn`: expiry formatted as 1m for 1 minute, 2days etc (similar to jsonwebtoken)

## Reporting Issues

If you encounter bugs or unexpected behavior:

1. Check the [issues](https://github.com/alaanpay/s2s-auth/issues) page.
2. Provide error messages, stack traces, and usage details.
3. Include your Node.js and library version.

## License

MIT