Multiple cookies added not merged into single HTTP header in Spring Webflux

Question

I'm trying to send a request using Spring Webflux's WebClient including multiple cookies. My code looks like this:

Mono<Void> loginCall = webClient.post()
                           .uri("/Sites/Login")
                           .cookie("key1", "value1")
                           .cookie("key2", "value2")
                           .cookie("key3", "value3")
                           .exchange()
                           .flatMap(clientResponse -> clientResponse.bodyToMono(Void.class));

What I receive on my endpoint looks like this (note the multiple cookie headers):

$ nc -l -p 8989
POST /Sites/Login HTTP/1.1
user-agent: ReactorNetty/0.8.11.RELEASE
host: localhost:8989
accept: */*
transfer-encoding: chunked
cookie: key1=value1
cookie: key2=value2
cookie: key3=value3

My expectation is to receive a HTTP request like this (a single cookie header):

cookie: key1=value1; key2=value2; key3=value3

I'm using Spring Boot 2.1.8.

I've tried numerous ways but everything I tried results in multiple cookie headers. The HTTP specification is quite clear about the fact that multiple cookie headers must not be used (and my web server receiving this request doesn't like it either).

How do I add multiple cookies to a WebClient request so that they are merged into a single HTTP header? (Yes, I can start setting the header manually and merge the cookies, but this somehow feels wrong)

Answer 1

Had the same problem, the only way I found was to produce the 'Cookie' header manually like this (Groovy language):

UserInfo retrieveUserInfo(List<Cookie> cookies) {
    String cookieHeader = cookies.collect { "${it.name}=${it.value}" }.join('; ')
    return webClient
            .get()
            .uri('your API path here')
            .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
            .header(HttpHeaders.COOKIE, cookieHeader)
            .retrieve()
            .bodyToMono(UserInfo.class)
            .block()
}