API Gateway

API Gateway is a microservice pattern that involves a front-end layer that handles all the incoming requests from clients and routes them to appropriate microservices. The API Gateway acts as the entry point for client requests and abstracts all the underlying microservices. In this tutorial, we’ll be looking at the use of Zuul as an API Gateway.

Syntax

The syntax for using Zuul as an API Gateway:

zuul:
  routes:
    <route-name>:
      path: /<path>
      serviceId: <microservice-name>

Example

Consider the following application.yml file that defines Zuul as an API Gateway for two microservices, product-service and order-service:

server:
  port: 8080

spring:
  application:
    name: api-gateway

zuul:
  routes:
    product-service:
      path: /product/**
      serviceId: product-service
      
    order-service:
      path: /order/**
      serviceId: order-service

Explanation

In the example above, an api-gateway service is defined and acts as an entry point for two microservices, product-service and order-service. The routes element specifies a mapping between the incoming request URL and the corresponding microservice to which it should be routed.

For instance, an incoming request with the URL path /product/123 would be routed to the product-service microservice while an incoming request with the URL path /order/456 would be routed to the order-service microservice.

Use

By using Zuul as an API Gateway, you can abstract the underlying microservices and provide a unified interface for clients. This makes it easy to manage different microservices as separate components and deploy them independently.

Important Points

• Zuul is a popular Java-based API Gateway implementation that makes it easy to define routing rules for microservices.
• An API Gateway provides an entry point for client requests and abstracts the underlying microservices.
• Using an API Gateway makes it easy to deploy, manage, and scale microservices independently.

Summary

An API Gateway is a powerful microservice pattern that provides a unified entry point for client requests and abstracts the underlying microservices. By using Zuul as an API Gateway, you can define routing rules for different microservices and abstract them from the client. Zuul makes it easy to deploy, manage, and scale microservices independently.