Spring Boot 4 Microservices & REST APIs · 강의

Spring Cloud Gateway를 사용한 API 게이트웨이

요청을 라우팅하고 필터를 적용하며 마이크로서비스를 보호하도록 Spring Cloud Gateway를 설정합니다.

Spring Cloud Gateway를 사용한 API 게이트웨이은(는) CoddyKit의 무료 Spring Boot 4 Microservices & REST APIs 강의입니다. 이것은 3개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Spring Boot 4 Microservices & REST APIs 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Spring Boot 4 Microservices & REST APIs 강의에는 총 3개의 강의가 포함되어 있습니다.

이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.

Why an API Gateway?

Microservices are great for building scalable applications, but they can introduce complexity. Imagine having many services, each with its own address and port.

An API Gateway acts as a single, unified entry point for all client requests. It funnels incoming traffic to the correct microservice, simplifying how clients interact with your backend.

What is Spring Cloud Gateway?

Spring Cloud Gateway (SCG) is a powerful, reactive API Gateway built on Spring Framework 5, Project Reactor, and Spring Boot 2. It's designed for high performance and scalability.

It provides flexible routing based on requests.
Enables dynamic filtering of requests and responses.
Integrates seamlessly with other Spring Cloud projects.

Setting Up Your Gateway Project

To create a Spring Cloud Gateway application, start with a standard Spring Boot project. The key is to add the spring-cloud-starter-gateway dependency.

This dependency pulls in everything needed to transform your Spring Boot app into an intelligent gateway. Remember to include the spring-cloud-dependencies in your dependencyManagement section.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.5</version>
    <relativePath/>
  </parent>
  <groupId>com.coddykit</groupId>
  <artifactId>gateway</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>gateway</name>
  <description>Demo project for Spring Cloud Gateway</description>
  <properties>
    <java.version>17</java.version>
    <spring-cloud.version>2023.0.1</spring-cloud.version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
</project>

Defining Basic Routes

Routes are the core of an API Gateway. They tell the gateway how to forward incoming requests to the correct backend service. Routes are defined using predicates and a target URI.

Here, the Path=/hello/** predicate matches any request path starting with /hello/ and routes it to http://localhost:8081.

server:
  port: 8080

spring:
  application:
    name: api-gateway
  cloud:
    gateway:
      routes:
        - id: hello_route
          uri: http://localhost:8081
          predicates:
            - Path=/hello/**

Testing Your Gateway Route

To test the route, you'd typically have a backend microservice running. Let's imagine a simple 'hello-service' running on http://localhost:8081 that responds to any /hello/** path.

Start your Gateway application (e.g., on port 8080).
Make a request to http://localhost:8080/hello/world.
The Gateway intercepts it and forwards it to http://localhost:8081/hello/world.
The response from 'hello-service' is then sent back to the client via the Gateway.

Introducing Gateway Filters

Gateway Filters are functions that allow you to modify requests and responses as they pass through the gateway. They are incredibly powerful for implementing cross-cutting concerns.

Request Filters: Modify the request before it reaches the target service.
Response Filters: Modify the response before it's sent back to the client.

Filters can be applied globally to all routes or specifically to individual routes.

Applying a Simple Filter: AddRequestHeader

Let's enhance our hello_route with a filter. The AddRequestHeader filter is a built-in filter that adds a specified header to the request before forwarding it.

This is useful for injecting correlation IDs, security tokens, or origin information into requests sent to downstream services.

server:
  port: 8080

spring:
  application:
    name: api-gateway
  cloud:
    gateway:
      routes:
        - id: hello_route_with_header
          uri: http://localhost:8081
          predicates:
            - Path=/hello/**
          filters:
            - AddRequestHeader=X-Request-Source, Gateway

Centralizing Security with Gateway

An API Gateway is an ideal place to centralize security mechanisms for your microservices. Instead of implementing authentication and authorization in every service, the gateway can handle it once.

Authentication: Validate user credentials or tokens (e.g., JWT).
Authorization: Check if the authenticated user has permission for the requested resource.
If checks pass, the request proceeds; otherwise, it's rejected at the gateway level.

Beyond Built-in Filters: Custom Filters

While Spring Cloud Gateway provides many useful built-in filters, you might need custom logic. You can create your own filters by implementing the GlobalFilter and Ordered interfaces.

Custom filters are perfect for unique logging requirements, advanced metrics collection, or bespoke security checks that apply across your entire API landscape.

Gateway Concepts Check

Test your understanding of API Gateway fundamentals!

Recap: API Gateway Power

Great job! In this lesson, we explored the crucial role of an API Gateway in a microservices environment, specifically using Spring Cloud Gateway.

We understood its purpose as a single entry point.
Learned to configure basic routing with predicates.
Discovered how filters can modify requests and responses.
Touched upon its importance in centralizing security.

API Gateways are essential for building robust, secure, and manageable microservice systems.

자주 묻는 질문

“Spring Cloud Gateway를 사용한 API 게이트웨이” 강의는 무료인가요?

네 — “Spring Cloud Gateway를 사용한 API 게이트웨이” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Spring Boot 4 Microservices & REST APIs 강의 전체를 잠금 해제할 수 있습니다. Spring Boot 4 Microservices & REST APIs 강의에는 총 3개의 강의가 포함되어 있습니다.

“Spring Cloud Gateway를 사용한 API 게이트웨이”에서 뭘 배우나요?

요청을 라우팅하고 필터를 적용하며 마이크로서비스를 보호하도록 Spring Cloud Gateway를 설정합니다. 브라우저에서 직접 실행하는 실습 코드로 Spring Boot 4 Microservices & REST APIs을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.

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