Lab#27 Making changes inside the gateway server.

In this lab we will make some changes inside the gateway. The first one is to accept lowercase letters in the url for the service name. We will also add some custom routing. Step#1 Update the application.yml for the gateway to add the property shown and restart the gatewayserver. This means that the gateway will accept service names in lowercase.

    name: gatewayserver
  config:
    import: "optional:configserver:http://localhost:8071" # Lab 22
  cloud:
    gateway:
      server:
        webflux:
          discovery:
            locator:
              enabled: true
              lower-case-service-id: true # lab 27

Step#2 Test using Postman

POST localhost:8072/loans/api/loans?mobileNumber=0871234567

Figure 1: Test lowercase letters, e.g. /loans/api/loans, Using Postman

Step#3 To demonstrate custom routing we will include “tusbank” in the url received by the gateway and map it to the appropriate url. See examples below.

http://localhost:8072/tusbank/accounts/api/account  ->http://localhost:8072/accounts/api/account
http://localhost:8072/tusbank/loans/api/loans. -> http://localhost:8072/loans/api/loans.
http://localhost:8072/tusbank/cards/api/cards. -> http://localhost:8072/cards/api/cards

Create a Bean inside the main application class in the gatewayserver – given. This defines the routing location configurations. This invokes a filter to re-write paths.

@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>.*)", "/${segment}")
                .addResponseHeader("X-Response-Time", LocalDateTime.now().toString()))
                .uri("lb://ACCOUNTS"))
                .route(p -> p
                .path("/tusbank/loans/**")
                .filters(f -> f.rewritePath("/tusbank/loans/(?<segment>.*)", "/${segment}")
                .addResponseHeader("X-Response-Time", LocalDateTime.now().toString()))
                .uri("lb://LOANS"))
                .route(p -> p
                .path("/tusbank/cards/**")
                .filters(f -> f.rewritePath("/tusbank/cards/(?<segment>.*)", "/${segment}")
                .addResponseHeader("X-Response-Time", LocalDateTime.now().toString()))
                .uri("lb://CARDS")).build();
    }
}

Step 4: Test the API so that the new url is invoked.

POST localhost:8072/tusbank/accounts/api/accounts

POST Account

{
    "name": "Joe O'Regan",
    "email": "joe@student.tus.ie",
    "mobileNumber": "0871234567"    
}

Figure 2: tusbank/accounts

Step 5: Check the actuator endpoints and routes. You will see that all routes from the default configuration are available and can still be called.

http://localhost:8072/actuator/

Figure 3: actuator

http://localhost:8072/actuator/gateway/routes

Figure 4: actuator gateway routes

Both the default and the custom routes are available.

GET localhost:8072/accounts/api/accounts?mobileNumber=1231234444

Figure 5: /accounts route

GET localhost:8072/tusbank/loans/api/loans?mobileNumber=0871234567

Figure 6: /tusbank/loans route

Step 6: To disable all the default routes and avoid confusion, update the application.yml to set gateway.discovery.locator.enabled to false. Now we only have the 3 scenarios remaining and default behaviour is disabled.

    name: gatewayserver
  config:
    import: "optional:configserver:http://localhost:8071" # Lab 22
  cloud:
    gateway:
      server:
        webflux:
          discovery:
            locator:
              enabled: false
              lower-case-service-id: true # lab 27

http://localhost:8072/actuator/gateway/routes

Figure 7: Actuator Gateway Routes

GET localhost:8072/tusbank/accounts/api/accounts?mobileNumber=0871234567

Figure 8: Status 404

Default behaviour disabled – just using custom paths Step 7: In the bean we have also have the code or filter to add a header in the response. Check the response headers in Postman.

    @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())) // This
                        .uri("lb://ACCOUNTS"))

GET localhost:8072/tusbank/loans/api/loans?mobileNumber=0871234567

Figure 9: X-Response-Time