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Apply retry to each and every endpoint in the spring webflux application

I have created below webclient and using it inside of my service to make HTTP third party calls.
#Configuration
public class WebclientConfig {
#Bean
public WebClient webClient() {
// custom client connector with connection pool disabled is being used as by default the connection pooling is done and connection reset happens after some idle time.
return WebClient.builder()
.clientConnector(new ReactorClientHttpConnector(HttpClient.newConnection()))
.defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.defaultHeader(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE)
.build();
}
}
and in my service, I am calling the third party service like below.
private Flux<BusinessObject> getBusinessObjects(String serviceURL) {
return this.webClient.get()
.uri(serviceURL)
.retrieve()
.bodyToFlux(BusinessObject.class) //code below this, do I have to copy for each webclient request to configure the retry, even if the values are same
.retryWhen(Retry.backoff(3, Duration.of(2, ChronoUnit.SECONDS))
.doBeforeRetry((value) -> log.info("Retrying request " + value))
.filter(error -> error instanceof WebClientRequestException)
.onRetryExhaustedThrow((retryBackoffSpec, retrySignal) ->
new RuntimeException(retrySignal.failure().getMessage())));
}
My question is as in comment in above code.
I have multiple webclient calls, but I want to configure the retry backoff configuration at a single place. How can I do that? so that my code should look like below
private Flux<BusinessObject> getBusinessObjects(String serviceURL) {
return this.webClient.get()
.uri(serviceURL)
.retrieve()
.bodyToFlux(BusinessObject.class)
.somCommonRetryCodeWrappingTheRetryLogic();
}

You can use transform operator for this purpose:
private Flux<BusinessObject> getBusinessObjects(String serviceURL) {
return this.webClient.get()
.uri(serviceURL)
.retrieve()
.bodyToFlux(BusinessObject.class)
.transform(originalFlux -> wrapWithRetry(originalFlux));
}
private <T> Flux<T> wrapWithRetry(Flux<T> originalFlux) {
return originalFlux
.retryWhen(Retry.backoff(3, Duration.of(2, ChronoUnit.SECONDS))
.doBeforeRetry((value) -> log.info("Retrying request " + value))
.filter(error -> error instanceof WebClientRequestException)
.onRetryExhaustedThrow((retryBackoffSpec, retrySignal) ->
new RuntimeException(retrySignal.failure().getMessage())));
}
Only drawback is that if you have Mono use cases as well then you need to implement it twice.
If that is still too much copy-paste, you can consider defining an ExchangeFilterFunction to apply retry for every WebClient call automatically. Something like this:
WebClient.builder()
// ...
.filter((request, next) -> next.exchange(request).retry()) // add full retry config here
.build();

How to convert Spring WebClient Response to ResponseEntity?

I'm able to return ResponseEntity using toEntity() method like below:
#GetMapping("/uri")
public Mono<ResponseEntity<Data[]>> methodName() {
return webClient
.get()
.uri("http://localhost:8088/externalService")
.accept(MediaType.APPLICATION_JSON)
.retrieve()
.toEntity(Data[].class);
}
But I want to process response headers before returning.
The above code converts WebClient response to ResponseEntity and returns immediately but I want to store it in a ResponseEntity variable, process it, and then return the ResponseEntity back.
I referred this -> Spring WebClient Documentation
WHen I tried to store it in a varibale, I get this error -> "block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-3"

You can simply use the Reactor's map operator to modify the headers:
return webClient
.get()
.uri("http://localhost:8088/externalService")
.accept(MediaType.APPLICATION_JSON)
.retrieve()
.toEntity(Data[].class)
.map(responseEntity -> responseEntity.getHeaders().add("header", "header-value");
Alternatively, you can use .handle operator in order to provide response processing:
.handle((responseEntity, sink) -> {
if(!isValid(responseEntity)){
sink.error(new InvalidResponseException());
} else if (isOk(responseEntity))
sink.next(responseEntity);
}
else {
//just ignore element
}
})

Spring Starter Web dependency was missing in my pom.xml. Found it and added it back.
Now able to get WebClient response in ResponseEntity format.

Spring Cloud API Gateway Routing based on data in JWT

I am using Spring Cloud Gateway, I want to route incoming request to ServiceA or ServiceB based on a value in the JWT token. So basically I want to extract the Token and get a userId from it and based on that information route to either service-a and service-b.
So the incoming request is something like "/v1/customers" and I need to prefix it with either /service-a/v1/customers to that it will be route to urlServiceA.
Here is the code of my Routes.
#Bean
public RouteLocator myRoutes(RouteLocatorBuilder builder) {
String urlServiceA = "a";
String urlServiceB = "b";
return builder.routes()
.route(r -> r.path("/service-a/v1/**")
.filters(f -> f.filter(authentication))
.uri(urlServiceA))
.route(r -> r.path("/service-b/v1/**")
.filters(f -> f.filter(authentication))
.uri(urlServiceB))
.build();
}
How can I do it ? Please help.
Thanks

Unable to forward Request to URI with context-path

I am unable to forward my request to a URI with contextpath.
For example I am requesting my Spring cloud gateway server with
http://localhost:1010/mygateway/server/date
And I expect it to forward to
http://myapiserver.com/xyzapi/v1/server/date
But It gives me 404
#Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
return builder.routes()
.route("api-server-date", r -> r.host("**")
.and()
.path("/mygateway/server/date")
.filters(f -> f.stripPrefix(1))
.uri("https://myapiserver.com/xyzapi/v1"))
.build();
}
It works when I change my configuration to this
#Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
return builder.routes()
.route("api-server-date", r -> r.host("**")
.and()
.path("/mygateway/xyzapi/v1/server/date")
.filters(f -> f.stripPrefix(1))
.uri("https://myapiserver.com"))
.build();
}
I don't know what configuration I am providing wrong. It should work.
All I want is to use
https://myapiserver.com/xyzapi/v1
As my URI. Meaning all Incoming traffic to my spring cloud gateway server should forward to this URL after appending the incoming url
Kindly suggest what is wrong ? Or is it something not possible with Spring Cloud Gateway ?

I think what you want (looking at online samples) is:
#Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
String requestHandlerUrl = "http://myapiserver.com/xyzapi/v1/server/date";
return builder.routes()
.route("api-server-date", r -> r.host("**")
.and()
.path("/mygateway/server/date")
.filters(f -> f.stripPrefix(1))
.uri(requestHandlerUrl)
.build();
}
... so that requests made to whatever host your app is deployed on are forwarded/passed to requestHandlerUrl as the destination.
It looks as if /mygateway/server/date is the "shortcut" or alias for the URL you actually want to handle the request.
Some examples here: https://cloud.spring.io/spring-cloud-gateway/multi/multi__configuration.html#_fluent_java_routes_api

Why does this simple Webflux Controller calls the Webclient retrieve method twice?

I have a very simple Webflux controller that just do a GET request to another service endpoint and returns a simple JSON list. The problem is the remote endpoint is always called twice.
This issue doesn't happen if I used Mono as the return type of the controller instead of Flux!
// This calls "/remote/endpoint" twice!
#GetMapping("/blabla")
fun controller() : Flux<JsonNode> {
return webClient.get()
.uri("/remote/endpoint")
.retrieve()
.bodyToMono(JsonNode::class.java)
.flatMapIterable { body ->
body.get("data")
}
}
// This calls "/remote/endpoint" once.
#GetMapping("/blabla")
fun controller() : Mono<JsonNode> {
return webClient.get()
.uri("/remote/endpoint")
.retrieve()
.bodyToMono(JsonNode::class.java)
.map { body ->
body.get("data")
}
}