[SpringCloudGateway]: Post filters are not executed after endpoint redirection timeout

[deepak-chhetri]

Spring cloud Gateway version: 4.1.0

We have implemented couple of custom Ordered Global Pre and Post filters in spring cloud gateway application. These pre global filters are getting executed for any incoming requests before redirecting to configured endpoint. And all post global filters are getting executed after endpoint call is completed successfully and response is received.

We have observed that these post filters are getting executed for other 4xx, like 404 (Not Found), 401(Unauthorized), and 5xx, like 503(Service Unavailable), 500 (Internal Server error), error response from endpoint call.

However, we have observed that these post global filters are not getting executed when the endpoint call is getting timeout, that is 504 Gateway Timeout response is received. Global response timeout is configured as 30sec as follows and endpoint call is taking more than 30 sec to process the request:

spring:
  cloud:
    gateway:
      httpclient:
        connect-timeout: 30000
        response-timeout: 30000

All the three global post filters are implemented in following pattern:

@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        <list of statements that modify the response in exchange object>
   }));
}

@Override
public int getOrder() {
   return POST_FILTER_BASE_ORDER - 3;  // POST_FILTER_BASE_ORDER = 1000
}

Is it an expected behavior from Spring Cloud Gateway framework or defect? Any help to resolve the issue is much appreciated.

[shashikanth8639]

@deepak-chhetri can you share the sample post-filter logic you have implemented?

[deepak-chhetri]

@deepak-chhetri can you share the sample post-filter logic you have implemented?

@shashikanth8639 Post filter is implemented in following way:

@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        final ResponseCookie  resCookie = ResponseCookie.from(this.cookieName, "invalidated").httpOnly(true).secure(true).path("/").maxAge(0).build();
        exchange.getResponse().addCookie(resCookie);
   }));
}

This post filter executes for 404 and 503 response status from endpoint, however fails to execute when API gateway times-out the endpoint call (endpoint take more than 30sec to respond).

[shashikanth8639]

@deepak-chhetri have you tried using the onError method?

[deepak-chhetri]

@deepak-chhetri have you tried using the onError method?

Thanks @shashikanth8639 for sharing the pointer. Do you mean Mono.onError()(publisher) method?

However I need to figure out why post filters are not executing when endpoint call gets timeout so that better error handling mechanism can be implemented. Since for other 4xx and 5xx status code, post filters are getting executed.

[spencergibb]

400 and 500 errors are responses from the server. A timeout is a local exception. Have you tried https://github.com/spring-cloud/spring-cloud-gateway/issues/3264#issuecomment-1946246543

[spring-cloud-issues]

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[spring-cloud-issues]

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[deepak-chhetri]

400 and 500 errors are responses from the server. A timeout is a local exception. Have you tried #3264 (comment)

@spencergibb Spring Cloud Gateway is timeout the downstream endpoint request. Downstream endpoint request is triggered by framework class NettyRoutingFilter class (read-only byte code). Where should I try adding onError() operator for timeout request by gateway?