Lab#33 Implementing the re-try pattern in the gateway.

Step#1 We will implement the re-try filter in the gateway for the loans microservice.

import java.time.Duration; // Lab 33
import java.time.LocalDateTime;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.http.HttpMethod; // Lab 33

@SpringBootApplication
public class GatewayserverApplication {

    public static void main(String[] args) {
        SpringApplication.run(GatewayserverApplication.class, args);
    }

    @Bean
    RouteLocator tusBankRouteconfig(RouteLocatorBuilder routeLocatorBuilder) { // Lab 27
        return routeLocatorBuilder.routes()
                .route(p -> p.path("/tusbank/accounts/**")
                        .filters(f -> f.rewritePath("/tusbank/accounts/(?<segment>.*)", "/${segment}")
                                .addResponseHeader("X-Response-Time", LocalDateTime.now().toString())
                                .circuitBreaker(config -> config.setName("accountsCircuitBreaker") // lab 29
                                        .setFallbackUri("forward:/contactSupport"))) // lab 30
                        .uri("lb://ACCOUNTS"))
                .route(p -> p.path("/tusbank/loans/**")
                        .filters(f -> f.rewritePath("/tusbank/loans/(?<segment>.*)", "/${segment}")
                                .addResponseHeader("X-Response-Time", LocalDateTime.now().toString())
                                .retry(retryConfig -> retryConfig.setRetries(3).setMethods(HttpMethod.GET)
                                        .setBackoff(Duration.ofMillis(100), Duration.ofMillis(1000), 2, true))) // Lab 33
                        .uri("lb://LOANS"))

Step#2 To test this we will make some changes in the loans controller by adding a logger statement. This will show how many times the request is invoked.

    @GetMapping("/contact-info")
    public ResponseEntity<LoansContactInfoDto> getContactInfo() {
        logger.debug("Invoked loans contact-info API"); // Lab 33
        return ResponseEntity.status(HttpStatus.OK).body(loansContactInfoDto);
    }

Figure 1. Logger message appears 4 times, once for first attempt, then 3 by retries

Figure 2. After 3 Retries Status 504 Gateway Timeout