Spring Cloud Gateway doesn't add X-Forwarded-Prefix header

[RobMaskell]

I have working zuul config and wanted to convert it to spring cloud gateway but I'm hitting a problem with the spring data rest / hateos response from my back-end api.

I have my gateway at http://localhost:8888 and access the api with http://localhost:8888/api/foo, the backend api server is at http://localhost:7777

The problem is that the /api is missing from the hateoas generated URIs in the response coming back.

The zuul config I'm replicating is as follows

application.properties

server.port=8888

zuul.routes.api.path=/api/**
zuul.routes.api.url=http://localhost:7777

zuul.add-proxy-headers=true
ribbon.eureka.enabled=false

The config for spring cloud gateway is as follows

application.properties

server.port=8888

spring.cloud.gateway.forwarded.enabled=true
spring.cloud.gateway.x-forwarded.enabled=true
spring.cloud.gateway.x-forwarded.forEnabled=true
spring.cloud.gateway.x-forwarded.protoEnabled=true

java api routes config

    @Bean
    public RouteLocator routeLocator(RouteLocatorBuilder builder) {
        return builder.routes()
                .route("api", r ->
                        r.path("/api/{segment}")
                            .filters(f -> f
//                                    .stripPrefix(1)
                                    .setPath("/{segment}")
                            )
                            .uri("http://localhost:7777")
                )
                .build();
    }

I've tried with and without the x-forwarded properties and it's the same with setPath and stripPrefix and I'm out of ideas now.

[RobMaskell]

Did a bit more investigation comparing headers added by zuul and S-C-G and it seems the difference is the X-Forwarded-Prefix header isn't being added

[RobMaskell]

I've created a minimal app for another gateway issue with chains of proxies that I'll be opening but it also shows this issue https://github.com/RobMaskell/gatewayissues.

To reproduce, bootRun the 'api' and 'web' modules in the IDE and access http://locahost:8888/api/ and look at the resulting json response, note the lack of /api in the Spring Hateoas generated URIs (because it uses spring URI builder that picks up on x-forwarded-prefix).

Don't know if this is an enhancement or needs documenting as unsupported but I feel Spring projects should be consistent in support for headers especially in simple cases like the StripPrefix filter.

If considered a valid bug or enhancement then I can look at submitting a PR for StripPrefix at least.

[ryandawsonuk]

I am also hitting this in Kubernetes (on AWS). I saw the same behaviour with nginx ingress before adding the annotation 'nginx.ingress.kubernetes.io/x-forwarded-prefix: "true"'. I wonder if the problem is just that XForwardedHeadersFilter doesn't included X-Forwarded-Prefix. I am trying to find out. (I notice from RobMaskell/gatewayissues that @RobMaskell was able to add a filter with "- AddRequestHeader=x-forwarded-prefix, /api" but I am using discovery locator so don't have a fixed path I can use.)

[RobMaskell]

@ryandawsonuk I couldn't find any x-forwarded-prefix related code in the x-forwarded filter so I came to the conclusion that it was unsupported for now

[ryandawsonuk]

There is a header called X-Original-URI that contains the path with the prefix in front. From this it is possible to extract the prefix. I tried overriding the XForwardedHeadersFilter class and found that it did then set the prefix and the links in the hateoas are then correct.

[RobMaskell]

I don't remember seeing that header in my case so maybe that will just work for you and not be a generic solution?

[ryandawsonuk]

Might be that it's an nginx thing. @RobMaskell Were you getting to the gateway via an ingress?

[RobMaskell]

@ryandawsonuk an Ingress yes but a garden variety GCP HTTP LB Ingress