When using Feign for communication between microservices, requests may time out due to network latency and other reasons. To solve this problem, we can configure Feign to set a timeout.
Configure the timeout for Feign
When using Feign, we can set the timeout for requests through configuration. Specifically, we can add the following properties to the application's configuration file:
=5000
=5000
In the configuration above, we set the connection timeout time and read timeout time to 5 seconds. You can also configure the timeout time for the Feign client by using the @FeignClient annotation in the Java configuration class of the application:
@FeignClient(name = "user-service", configuration = )
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable int id);
@PostMapping("/users")
User createUser(@RequestBody User user);
@PutMapping("/users/{id}")
User updateUser(@PathVariable int id, @RequestBody User user);
@DeleteMapping("/users/{id}")
void deleteUser(@PathVariable int id);
}
In the above example, we use the configuration attribute in the @FeignClient annotation to specify the UserClientConfiguration class, which contains the timeout time configuration for the Feign client:
@Configuration
public class UserClientConfiguration {
@Bean
public requestOptions() {
return new (5000, 5000);
}
}
In the above example, we use the @Configuration annotation to mark the UserClientConfiguration class, indicating that it is a Spring configuration class. We then use the @Bean annotation to mark the requestOptions method, which returns an object containing the connection timeout and read timeout, both set to 5 seconds here.
Handling timeout exceptions
Feign throws a FeignException when a request times out. We can use a try-catch block to catch this exception and take appropriate action. For example, we can use the retry mechanism to re-execute the request or return a default value or an error message.
Here is an example:
@RestController
public class UserController {
private final UserClient userClient;
public UserController(UserClient userClient) {
= userClient;
}
@GetMapping("/users/{id}")
public User getUser(@PathVariable int id) {
try {
return (id);
} catch (FeignException e) {
throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "Failed to get user", e);
}
}
}
In the above example, we use a try-catch block in the getUser method to catch the FeignException exception. This exception is thrown if the request times out. In the catch block, we use the ResponseStatusException class to throw an HTTP 500 error indicating a failure to get user information. Also, we pass the original exception FeignException as a parameter to the ResponseStatusException class to log it.
Handling Feign's timeout fallback
In addition to using a retry mechanism and returning default values or error messages to handle timeout exceptions, Feign provides a mechanism for handling timeout issues, known as a timeout fallback. A timeout fallback means that when a request times out, Feign will process the request using the specified fallback method or fallback class. This ensures that even if a request times out, the application can continue to run without crashing.
The following is an example of using the timeout fallback mechanism:
@FeignClient(name = "user-service", fallback = )
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable int id);
@PostMapping("/users")
User createUser(@RequestBody User user);
@PutMapping("/users/{id}")
User updateUser(@PathVariable int id, @RequestBody User user);
@DeleteMapping("/users/{id}")
void deleteUser(@PathVariable int id);
}
@Component
public class UserClientFallback implements UserClient {
@Override
public User getUser(int id) {
return new User(id, "Fallback User");
}
@Override
public User createUser(User user) {
return new User(-1, "Fallback User");
}
@Override
public User updateUser(int id, User user) {
return new User(id, "Fallback User");
}
@Override
public void deleteUser(int id) {
// Do nothing
}
}