Spring Cloud Gateway with Spring Cloud Discovery

Spring Cloud Gateway and Spring Cloud Discovery are powerful tools for building microservices architectures. Spring Cloud Gateway acts as an API gateway, routing requests to the appropriate microservices. Spring Cloud Discovery provides a registry for microservices, enabling dynamic service discovery and load balancing.

In this comprehensive guide, we’ll delve into the integration of Spring Cloud Gateway with Spring Cloud Discovery using Spring 3.1.x and the latest version of Spring Cloud, empowering you to build resilient and scalable microservices architectures.

Prerequisites

Before embarking on this journey, ensure you have the following prerequisites in place:

• Java Development Kit (JDK) 11 or higher
• Maven or Gradle
• Spring Boot 2.7.0 or higher
• Spring Cloud Dependency Management (BOM)

Maven Dependencies

For Maven-based projects, include the following dependencies in your pom.xml file:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

Gradle Dependencies

For Gradle-based projects, include the following dependencies in your build.gradle file:

dependencies {
    implementation "org.springframework.cloud:spring-cloud-starter-gateway"
    implementation "org.springframework.cloud:spring-cloud-starter-netflix-eureka-client"
}

Configuration Settings

1. Application.yml:

spring:
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true

2. bootstrap.yml:

spring:
  cloud:
    eureka:
      client:
        register-with-eureka: true
        fetch-registry: true
        service-url:
          defaultZone: http://localhost:8761

Dynamic Routes

Spring Cloud Gateway enables dynamic route discovery using Spring Cloud Discovery. This feature allows the gateway to automatically discover and configure routes based on the registered microservices in the registry.

1. Route Configuration:

routes:
  - id: kitchen-route
    uri: lb://kitchen
    predicates:
      - Path=/kitchen/**
  - id: tracker-route
    uri: lb://tracker
    predicates:
      - Path=/tracker/**

In this example, the gateway will automatically discover microservices named kitchen and tracker and create routes accordingly. The lb: prefix in the uri indicates load balancing across available instances of the microservice.

Dynamic Routes with Custom Locator

For more granular control over route discovery, you can implement a custom DiscoveryClientRouteDefinitionLocator. This class provides the flexibility to define routes based on custom criteria and logic.

Benefits of Spring Cloud Gateway with Spring Cloud Discovery

• Dynamic Routing: Automatically discover and configure routes based on registered microservices.
• Load Balancing: Distribute traffic across multiple instances of microservices for optimal performance and availability.
• Service Discovery: Eliminate the need for manual configuration of service URLs and endpoints.
• Centralized Management: Monitor and manage microservices from a single pane of glass.

Conclusion

Spring Cloud Gateway and Spring Cloud Discovery empower developers to build resilient and scalable microservices architectures with ease. By leveraging dynamic routes and centralized service discovery, you can simplify deployment and management, ensuring your microservices remain agile and responsive to changing demands.