====== Spring Cloud Gateway ======
  * [[https://spring.io/projects/spring-cloud-gateway|Spring Cloud Gateway]]
  * Spring Boot / WebFlux / Reactor 기반의 Non Blocking API Gateway.
  * [[java:zuul|Zuul]] 에 대응. Java/Spring 기반 개발자들에게는 Spring Cloud Gateway 가 더 나아 보인다.
    * 이 페이지에 API Gateway 설계에 대한 내용을 많이 정리해뒀음.
    * 결론, 특별한 경우가 아니면 API Gatway 사용하지 말라.
  * Java Code 기반 Routing 설정 가능

====== Routings ======
  * ''localhost:8080/get'' -> ''http://httpbin.org:80/get'' 으로 요청 라우팅<code java>
.route(p -> p.path("/get")
  .filters(f -> f.addRequestHeader("Hello", "World"))
  .uri("http://httpbin.org:80"))
 </code>
  * URL을 중간에 바꿔치기해서 라우팅 ''localhost:8080/api/v1/get'' -> ''http://httpbin.org:80/get'' 으로 요청 라우팅<code java>
.route(p -> p.path("/api/v1/get")
  .filters(f -> f.setPath("/get"))
  .uri("http://httpbin.org:80"))
</code>
  * PATH 앞에 떼어내기 ''localhost:8080/api/httpbin/get'' -> ''http://httpbin.org:80/get''<code java>
route("httpbin", p -> p.path("/api/httpbin/**")
   .filters(f -> f.stripPrefix(2))
 .uri("http://httpbin.org:80))
// '/api' - 1, '/httpbin' - 2 해서 2 path 건너뛰기
</code>
  * PATH Variable 정규표현식 ''localhost:8080/api/httpbin/get/123'' -> ''http://httpbin.org:80/get/123'', 단 ''/get/abc'' 는 거부됨<code java>
route("httpbin", p -> p.path("/api/httpbin/get/{num:[0-9]+}")
   .filters(f -> f.stripPrefix(2))
 .uri("http://httpbin.org:80))
</code>
  * Path Rewrite : [[https://stackoverflow.com/questions/48632054/spring-cloud-gateway-2-0-forward-path-variable|java - Spring Cloud Gateway 2.0 forward path variable - Stack Overflow]]<code java>

route("userById", t -> t.path("/users/**")
  .filters(rw -> rw.rewritePath("/users/(?<segment>.*)", "/users/${segment}"))
  .uri("http://localhost:8080/users/"))
</code>

====== Actuator ======
''implementation 'org.springframework.boot:spring-boot-starter-actuator''' 의존성 추가

<code>
management.endpoint.gateway.enabled=true # default value
management.endpoints.web.exposure.include=gateway
</code>

===== 참조 =====
  * [[https://spring.io/guides/gs/gateway/|Getting Started · Building a Gateway]]
  * [[https://github.com/spring-cloud-samples/spring-cloud-gateway-sample|Spring Cloud Gateway Sample]]
  * [[https://www.baeldung.com/spring-cloud-gateway|Exploring the New Spring Cloud Gateway | Baeldung]]
  * [[https://aboullaite.me/spring-cloud-gateway/|A look into Spring Cloud Gateway!]]
  * [[https://dzone.com/articles/spring-cloud-gateway-configuring-a-simple-route|Spring Cloud Gateway - Configuring a Simple Route - DZone Microservices]]
  * [[https://springboot.cloud/26|Spring Cloud Gateway 2.1.0RELEASE 레퍼런스]]
  * [[https://www.baeldung.com/spring-cloud-gateway-routing-predicate-factories|Spring Cloud Gateway Routing Predicate Factories | Baeldung]]
  * [[https://www.popit.kr/spring-cloud-gateway/|Spring Cloud Gateway | Popit]]