I. Introduction

In spring cloud, zuul is used to implement the gateway function. The client's requests first go through the load balancing Ngnix, then to the service gateway (zuul cluster), and then to the specific services. Zuul's main functions are route forwarding and filter. Routing function is a part of microservice, such as / api/server1 forwarding to server1 service. Zuul default and Ribbon combine to realize the function of load balancing.

Two, build

First POM file

<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
 Then in applicaton Class annotated@EnableZuulProxy，open zuul Function 

@SpringBootApplication
@EnableZuulProxy
@EnableEurekaClient
@RefreshScope
public class HfzZuulApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(HfzZuulApplication.class, args);
    }
}

yml is configured as follows.

eureka:
  client:
    serviceUrl:
      defaultZone: http://name:pass@IP/eureka/
  instance:
    ip-address: Ip address
    prefer-ip-address: true
server:
  port: 8769
spring:
  application:
    name: service-zuul
  sleuth:
    sampler:
      percentage: 1.0
  cloud:
    config:
      discovery:
        enabled: true
        service-id: CONFIG-SERVER
      label: master
      profile: dev
      name: hfz-zuul
      username: name
      password: pass

  the above is configured in the project. In order to make the project more flexible, the routing configuration is placed on github, which can be read dynamically.

zuul:
  routes:
    api-a:
      path: /api-a/**
      serviceId: service-ribbon
    api-b:
      path: /api-b/**
      serviceId: service-feign

Requests starting with / api-a / are forwarded to the service ribbon service; requests starting with / api-b / are forwarded to the service feign service.

III. service filtering

zuul can not only route, but also intercept some services through filtering, which can be used for security verification.  

public class MyFilter extends ZuulFilter{
 
private static Logger log = LoggerFactory.getLogger(MyFilter.class);
@Override
public String filterType() {
    return "pre";
}
 
@Override
public int filterOrder() {
    return 0;
}
 
@Override
public boolean shouldFilter() {
    return true;
}
 
@Override
public Object run() {
    RequestContext ctx = RequestContext.getCurrentContext();
    HttpServletRequest request = ctx.getRequest();
    log.info(String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString()));
    Object accessToken = request.getParameter("token");
    if(accessToken == null) {
        log.warn("token is empty");
        ctx.setSendZuulResponse(false);
        ctx.setResponseStatusCode(401);
        try {
            ctx.getResponse().getWriter().write("token is empty");
        }catch (Exception e){}
 
        return null;
    }
    log.info("ok");
    return null;
 }
}

filterType: returns a string representing the filter type. In zuul, four filter types with different life cycles are defined, as follows:

pre: before routing

Routing: routing time

post: after routing

Error: send error call

filterOrder: order of filtering

shouldFilter: logical judgment, whether to filter

run: concrete logic control of filter

Next you can test the access.