Implementing API Gateway | SpringBoot Microservices

We have 3 microservices for our Hotel Rating Application →

• UserService - localhost:8081/users

• HotelService - localhost:8082/hotels

• RatingService - localhost:8083/ratings

Above 3 microservices are already registered as Discovery Client on our Discover server.

Here we will try to implement API Gateway for our Hotel Rating Application -

Step 1 → Add dependencies.

• Cloud Bootstrap | SPRING CLOUD

• Gateway | SPRING CLOUD ROUTING

• Spring Reactive Web | WEB (Spring Cloud Gateway requires the Netty runtime provided by Spring Boot and Spring Webflux. It does not work in a traditional Servlet Container or when built as a WAR.)

• Eureka Discovery Client | SPRING CLOUD DISCOVERY

Step 2 → Register our API Gateway application as Discovery Client on our Discovery Server. For this we already have added dependencies in step 1 (“Cloud Bootstrap | SPRING CLOUD” and “Eureka Discovery Client | SPRING CLOUD DISCOVERY“). We just need to add the configurations, for which you refer the article -

Implementing Service Discovery Client in SpringBoot | Microservices

spring:
  application:
    name: ApiGateway

server:
  port: 8091


eureka:
  instance:
    prefer-ip-address: true
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:8761/eureka

(NOTE : Make sure your Discovery Server microservice is running on default port: 8761 (localhost:8761) otherwise the app won’t work maybe because it requires extra configurations.)

Step 3 → Configuring routes (Check “Spring Cloud Gateway” documentation for latest updates).

spring:
  cloud:
    gateway:
      routes:
      - id: USERSERVICE
        uri: lb://USERSERVICE
        predicates:
        - Path=/users/**

      - id: HOTELSERVICE
        uri: lb://HOTELSERVICE
        predicates:
        - Path=/hotels/**

      - id: RATINGSERVICE
        uri: lb://RATINGSERVICE
        predicates:
        - Path=/ratings/**

Now we can access these microservices endpoints as →

• UserService - localhost:8081/users → localhost:8091/users

• HotelService - localhost:8082/hotels → localhost:8091/hotels

• RatingService - localhost:8083/ratings → localhost:8091/ratings

So we can see that now we have a single point of entry for all our microservices which is our API Gateway microservice.

Please refer to “Spring Cloud Gateway” documentation for latest updates.