Fegin call 404 situation
1: Background introduction
Arpro has deployed two servers for production load. Both use the same nacos namespace.
Only one was updated. As a result, the request went to the one that was not updated, so a 404 problem occurred.
2. Basic introduction of OpenFeign
OpenFeign is Spring Cloud's secondary encapsulation of Feign, which supports Spring MVC annotations on the basis of Feign. OpenFeign's @FeignClient can parse Spring MVC's @RequestMapping @GetMapping and @PostMapping and so on.
how to use
- Add @EnableFeignClients to the startup class, scan the interface annotated with @FeignClient and register it in the spring container.
2. To use, we only need to create an interface and add the @FeignClient annotation to the interface. This annotation will analyze the interface under the @RequestMapping annotation, and generate an implementation class through a dynamic proxy to achieve load balancing and service invocation.
Environmental preparation
Prepare a Spring Cloud project, including a consumer, a service provider, using nacos as a service discovery and configuration center
project structure
provider
bootstrap.yml
startup class
@EnableDiscoveryClient
@SpringBootApplication
public class TestFeignApplication {
public static void main(String[] args) {
SpringApplication.run(TestFeignApplication.class, args);
}
}
UserController class
@RestController
@RequestMapping("/user")
public class UserController {
@GetMapping("/get")
public String findAll() {
return "服务调用成功";
}
}
Invoker
bootstrap.yml
startup class
@SpringBootApplication
@EnableDiscoveryClient
//扫描标有@FeignClient的接口
@EnableFeignClients("com.ctsi.sddx.feign")
public class NacosApplication {
public static void main(String[] args) {
SpringApplication.run(NacosApplication.class, args);
}
}
Feign interface
@FeignClient(value = "arpro-provider-one")//value为Feign调用的服务名，也是注册到nacos中的服务名
public interface UserFeign {
@GetMapping("user/get")
String findAll();
}
UserController class
@RestController
@RequestMapping("/user")
public class UserController {
@Resource
private UserFeign userFegin;
@PostMapping("feign")
public String getDeviceListByPage() {
return userFegin.findAll();
}
}
run project
Start the Invoker service and Provider service, and observe whether the services are registered successfully on nacos.
Under the arpro namespace, we can see that both services have been registered successfully.
The Invoker service calls the findAll() method in the Provider service,
and it can be seen that the OpenFeign call is successful. This is the most basic application of OpenFeign, isn't it very simple.
Three: The reproduction of feign calling 404
After we are familiar with the basic use of OpenFeign, we return to the topic of arpro production and deploy two servers for load. Both use the same nacos namespace.
Only one was updated. As a result, the request went to the one that was not updated, so a 404 problem occurred.
To reproduce the problem, first we need two sets of applications. I have prepared two programs, test-feign-2 and test-feign-5, which are completely consistent in code and inconsistent in service port number.
First, we need to register both sets of applications on nacos. Then there will be a total of two consumer services and two provider services.
You can see that they have been registered so far, two consumer instances, and two provider instances.
Make OpenFeign calls
If a consumer we start calls OpenFeign, it will be load balanced by nacos and distributed according to the weight, that is, both Providers may be called. If the code version of one of the providers is behind the other provider (for example, there is no corresponding interface), then it will appear, and if the provider whose code is behind is requested, a 404 problem will appear. Now let's simulate.
First look at the weights of the two provider services. You can see that the weights of the services are both 1. In this case, it is basically called on average. If the calls are made 4 times, the two providers are called twice, and there is a sequence relationship. Call the first One, then the second, and the first, and the second.
Modify the code of UserController whose port number is 9009
Comment out the findAll() method ; and restart the service
@RestController
@RequestMapping("/user")
public class UserController {
// @GetMapping("/get")
// public String findAll() {
// return "服务调用成功";
// }
}
carry out testing
The consumer makes an OpenFeign call.
The first successful call is the provider service with the correct code.
The second call fails, and the provider service with the code commented out is used.
404 problem successfully reproduced
Four: Summary
- You need to be in awe of the production environment
- For the production of codes in the two environments, a strict process system is required to ensure
- Feedback closed loop is required, such as test verification.
Technical means: - Since the codes of the two environments are consistent, can they be built uniformly and then pushed to their respective servers. This needs to be done in the next step, using automation to improve fault tolerance, such as using jenkins (unified construction, and push to the respective servers)
- For the use of OpenFeign, this blog only mentions simple applications, such as OpenFeign's timeout processing fuse log , which is not mentioned.
Five: Sublimation
- Production is no small matter, and one needs to be in awe of the production environment.
- We can have a variety of ways to deal with the problem, from the perspective of process system and technical means.
- What I have always learned in blogging is that completion is more important than perfection. Complete the established tasks within the specified time, and expand when there is spare time.