가드와 역할
NestJS 가드를 활용하여 경로를 보호하고 역할 기반 접근 제어(RBAC)를 구현하여 사용자 권한을 관리합니다.
가드와 역할은(는) CoddyKit의 무료 Next.js 15 Fullstack (App Router + Server Actions) 강의입니다. 이것은 6개 중 4번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Next.js 15 Fullstack (App Router + Server Actions) 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Next.js 15 Fullstack (App Router + Server Actions) 강의에는 총 6개의 강의가 포함되어 있습니다.
이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.
What are NestJS Guards?
In NestJS, Guards are special classes that decide if a given request should be processed by the route handler. Think of them as gatekeepers!
They sit between the incoming request and your application's logic, making authorization decisions.
- Authorization: Who is allowed to do what?
- Authentication: Who is this user? (Often handled before guards, but guards can confirm it).
Building a Basic Guard
All NestJS Guards must implement the CanActivate interface. This interface requires a single method: canActivate().
The canActivate() method returns a boolean, a Promise<boolean>, or an Observable<boolean>. If it returns true, the request proceeds; if false, it's blocked.
import { CanActivate, ExecutionContext, Injectable } from '@nestjs/common';
import { Observable } from 'rxjs';
@Injectable()
export class AuthGuard implements CanActivate {
canActivate(
context: ExecutionContext,
): boolean | Promise<boolean> | Observable<boolean> {
// Logic to determine if user is authorized
// For now, let's just allow it
return true;
}
}A Simple Authentication Check
Let's make our AuthGuard actually do something! We'll simulate checking if a user is 'logged in' by looking for a specific header.
The ExecutionContext provides access to the request, response, and more, allowing us to inspect the incoming request.
import { CanActivate, ExecutionContext, Injectable } from '@nestjs/common';
import { Observable } from 'rxjs';
@Injectable()
export class BasicAuthGuard implements CanActivate {
canActivate(
context: ExecutionContext,
): boolean | Promise<boolean> | Observable<boolean> {
const request = context.switchToHttp().getRequest();
// In a real app, you'd check JWT, session, etc.
// For this example, we check a simple header.
const hasAuthHeader = request.headers['authorization'] === 'Bearer secret-token';
return hasAuthHeader; // Only allow if header is correct
}
}Protecting Your Endpoints
To apply a guard, you use the @UseGuards() decorator. You can apply it to a single route handler or to an entire controller.
When applied to a controller, all routes within that controller will be protected by the guard.
import { Controller, Get, UseGuards } from '@nestjs/common';
import { BasicAuthGuard } from './common/guards/auth.guard';
@Controller('protected')
@UseGuards(BasicAuthGuard) // Protects all routes in this controller
export class ProtectedController {
@Get()
getProtectedData(): string {
return 'This data is protected!';
}
@Get('public')
getAnotherProtectedData(): string {
return 'More protected data.';
}
}
// src/app.module.ts
import { Module } from '@nestjs/common';
import { ProtectedController } from './app.controller';
@Module({
controllers: [ProtectedController],
providers: [],
})
export class AppModule {}
// src/main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
async function bootstrap() {
const app = await NestFactory.create(AppModule);
await app.listen(3000);
console.log('App running on http://localhost:3000');
}
bootstrap();Understanding RBAC
While basic authentication checks if a user is who they say they are, Role-Based Access Control (RBAC) checks what they are allowed to do.
With RBAC, users are assigned roles (e.g., 'admin', 'editor', 'viewer'), and permissions are granted to roles, not individual users.
- Role: A collection of permissions (e.g., 'admin' can 'create', 'read', 'update', 'delete').
- User: Assigned one or more roles.
- Resource: The data or functionality being accessed.
Marking Routes with Roles
To implement RBAC, we need a way to tell our guard which roles are allowed for a specific route. NestJS allows us to create custom decorators for this!
We'll create an @Roles() decorator to attach role metadata to our route handlers.
import { SetMetadata } from '@nestjs/common';
export const ROLES_KEY = 'roles';
export const Roles = (...roles: string[]) => SetMetadata(ROLES_KEY, roles);
// Example usage in a controller:
// @Roles('admin', 'editor')
// @Get('admin-only')
// someAdminMethod() { ... }The Roles Guard Logic
Now, let's build our RolesGuard. This guard will:
- Get the required roles from the route's metadata using the
Reflector. - Get the user's roles (e.g., from the request object after authentication).
- Compare them to see if the user has any of the required roles.
import { Injectable, CanActivate, ExecutionContext } from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { Observable } from 'rxjs';
import { ROLES_KEY } from '../decorators/roles.decorator';
@Injectable()
export class RolesGuard implements CanActivate {
constructor(private reflector: Reflector) {}
canActivate(
context: ExecutionContext,
): boolean | Promise<boolean> | Observable<boolean> {
const requiredRoles = this.reflector.getAllAndOverride<string[]>(ROLES_KEY, [
context.getHandler(),
context.getClass(),
]);
if (!requiredRoles) {
return true; // No roles defined, so access is allowed by default
}
const request = context.switchToHttp().getRequest();
// In a real app, 'user' would come from an authentication guard
// and contain actual user data including roles.
const user = request.user || { roles: ['viewer'] }; // Dummy user for example
const hasPermission = requiredRoles.some((role) => user.roles.includes(role));
return hasPermission;
}
}Stacking Guards for Protection
You can use multiple guards on a single route or controller. NestJS executes guards in the order they are listed in the @UseGuards() decorator.
If any guard returns false, the request is immediately blocked, and subsequent guards (and the route handler) are not executed.
- First: Authentication (Is the user logged in?)
- Second: Authorization (Does the user have the right role?)
Applying Guards and Roles
Let's see how our BasicAuthGuard, RolesGuard, and @Roles() decorator work together to protect an endpoint.
We'll simulate a user with the 'admin' role.
import { Controller, Get, UseGuards, Req } from '@nestjs/common';
import { BasicAuthGuard } from './common/guards/auth.guard';
import { RolesGuard } from './common/guards/roles.guard';
import { Roles } from './common/decorators/roles.decorator';
// Assume this comes from a real authentication process
interface User {
username: string;
roles: string[];
}
@Controller('admin')
@UseGuards(BasicAuthGuard, RolesGuard) // Guards applied in order
export class AdminController {
@Get('dashboard')
@Roles('admin') // Only users with 'admin' role can access
getAdminDashboard(@Req() req): string {
// For this runnable example's context, manually set user.
// In a real app, BasicAuthGuard would populate req.user.
req.user = { username: 'testuser', roles: ['admin'] };
return `Welcome to the Admin Dashboard, ${req.user.username}!`;
}
@Get('reports')
@Roles('admin', 'editor') // Admins or Editors can access
getReports(@Req() req): string {
req.user = { username: 'editoruser', roles: ['editor'] };
return `Accessing reports as ${req.user.username}.`;
}
}
// src/app.module.ts
import { Module } from '@nestjs/common';
import { AdminController } from './app.controller';
@Module({
controllers: [AdminController],
providers: [],
})
export class AppModule {}
// src/main.ts (unchanged from previous runnable example)
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
async function bootstrap() {
const app = await NestFactory.create(AppModule);
await app.listen(3000);
console.log('Admin app running on http://localhost:3000');
}
bootstrap();Guard & Role Check
Consider a NestJS route protected by @UseGuards(AuthGuard, RolesGuard) and @Roles('admin', 'moderator').
If a request comes in with a valid authentication token (passed by AuthGuard), but the authenticated user has only the role 'viewer', what will happen?
Guards & Roles Summary
Great job! In this lesson, you learned about:
- NestJS Guards: Gatekeepers that implement
CanActivateto control route access. @UseGuards(): Decorator to apply guards at controller or method level.- Role-Based Access Control (RBAC): Managing permissions based on user roles.
- Custom Decorators: Using
@SetMetadata()to attach custom data (like roles) to routes. Reflector: Used by guards to read metadata from routes.
Guards are powerful for authorization. Next, you might explore how to integrate Passport.js strategies for more robust authentication!
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네 — “가드와 역할” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Next.js 15 Fullstack (App Router + Server Actions) 강의 전체를 잠금 해제할 수 있습니다. Next.js 15 Fullstack (App Router + Server Actions) 강의에는 총 6개의 강의가 포함되어 있습니다.
“가드와 역할”에서 뭘 배우나요?
NestJS 가드를 활용하여 경로를 보호하고 역할 기반 접근 제어(RBAC)를 구현하여 사용자 권한을 관리합니다. 브라우저에서 직접 실행하는 실습 코드로 Next.js 15 Fullstack (App Router + Server Actions)을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.
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사전 경험은 필요하지 않습니다. CoddyKit의 Next.js 15 Fullstack (App Router + Server Actions)은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 6개 중 4번째 강의입니다.
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