Spring-cloud-sleuth: TraceRequestHttpHeadersFilter overrides all request headers in Spring Cloud Gateway

[zbin]

Oops, I'm not sure it is a bug or question.

I'm trying to integrate Spring Cloud Gateway and Spring Cloud Sleuth. In Spring Boot 2.1.2 and Spring Cloud Greenwich.RELEASE.

I found any of my request Header 'X-Forward-*' is missing.

After reading the source code, I found a HeaderFilters in the NettyRoutingFIlter and the TraceRequestHttpHeadersFilter was injected.

But TraceRequestHttpHeadersFilter is so strange. Why is its implementation covered instead of append?

class TraceRequestHttpHeadersFilter extends AbstractHttpHeadersFilter {
    private static final Log log = LogFactory.getLog(TraceRequestHttpHeadersFilter.class);

    static HttpHeadersFilter create(HttpTracing httpTracing) {
        return new TraceRequestHttpHeadersFilter(httpTracing);
    }

    private TraceRequestHttpHeadersFilter(HttpTracing httpTracing) {
        super(httpTracing);
    }

    public HttpHeaders filter(HttpHeaders input, ServerWebExchange exchange) {
        if (log.isDebugEnabled()) {
            log.debug("Will instrument the HTTP request headers");
        }

        Builder builder = exchange.getRequest().mutate();
        Span span = this.handler.handleSend(this.injector, builder);
        if (log.isDebugEnabled()) {
            log.debug("Client span  " + span + " created for the request. New headers are " + builder.build().getHeaders().toSingleValueMap());
        }

        exchange.getAttributes().put(SPAN_ATTRIBUTE, span);
        return new HttpHeaders(builder.build().getHeaders());
    }

    public boolean supports(Type type) {
        return type.equals(Type.REQUEST);
    }
}

ps: Forgive my English, I am still trying to learn it.

[marcingrzejszczak]

But TraceRequestHttpHeadersFilter is so strange. Why is its implementation covered instead of append?

What do you mean exactly? Can you create a test or sample that reproduces the issue?

[martinvisser]

@marcingrzejszczak The input argument is completely ignored in this method in TraceRequestHttpHeadersFilter, so that means that all updated headers, for example the Forwarded header, is removed from this list.

[marcingrzejszczak]

@martinvisser thanks for the issue report, I've managed to reproduce it and fix it. Please wait for the snapshots to be uploaded and double check that everything works fine.

[martinvisser]

@marcingrzejszczak Thanks for the fix, but I think this isn't completely correct yet.
For example, this is my "input":

[
Cookie:"test=value",
Accept:"*/*",
Accept-Encoding:"gzip,deflate",
User-Agent:"Apache-HttpClient/4.5.6 (Java/11.0.2)",
x-session-id:"397ec5c3-be7c-4473-a427-26327ec3bab0",
x-auth-user:"aaaa",
host:"localhost",
Forwarded:"proto=http;host=localhost;for="127.0.0.1:50243"",
X-Forwarded-For:"127.0.0.1",
X-Forwarded-Proto:"http",
X-Forwarded-Port:"80",
X-Forwarded-Host:"localhost"
]

Then the output is now:

[
Cookie:"test=value", "test=value",
Accept:"*/*", "*/*",
Accept-Encoding:"gzip,deflate", "gzip,deflate",
User-Agent:"Apache-HttpClient/4.5.6 (Java/11.0.2)", "Apache-HttpClient/4.5.6 (Java/11.0.2)",
x-session-id:"397ec5c3-be7c-4473-a427-26327ec3bab0", "397ec5c3-be7c-4473-a427-26327ec3bab0",
x-auth-user:"aaaa", "aaaa",
host:"localhost", "localhost",
Forwarded:"proto=http;host=localhost;for="127.0.0.1:50243"",
X-Forwarded-For:"127.0.0.1",
X-Forwarded-Proto:"http",
X-Forwarded-Port:"80",
X-Forwarded-Host:"localhost",
baggage_session-id:"397ec5c3-be7c-4473-a427-26327ec3bab0",
X-B3-Sampled:"1",
X-B3-TraceId:"62bc0de59f130256",
Connection:"Keep-Alive",
X-B3-SpanId:"d20d1f2d180451dd",
X-B3-ParentSpanId:"39fdbc9844fa9e01",
baggage-session-id:"397ec5c3-be7c-4473-a427-26327ec3bab0"
]

In other words, header values are duplicated.

[marcingrzejszczak]

Ah, I see. Let me reopen it and give it another go ;)

[marcingrzejszczak]

BTW it would be much easier with a sample from your side.

[marcingrzejszczak]

Ok, it should be fixed. Please wait for the snapshots and try again.

[martinvisser]

That's working perfectly!

[adrianotr]

This change introduced a new bug. If I have multiple headers with the same name, it discards everything and preserves only the first header.
That happens exactly because of this change:
https://github.com/spring-cloud/spring-cloud-sleuth/commit/1775ec1000d638a61dfcb852a54a8bdf2159ed18#diff-80efc26f63f80d00df56ec6edd649968R59

[marcingrzejszczak]

Can you provide more information or a test case that replicates the issue?

[marcingrzejszczak]

Oh you actually did https://github.com/spring-cloud/spring-cloud-sleuth/issues/1352