Reactive rest client headers injection in Quarkus

Question

I am following the guide of the new quarkus-resteasy-reactive-jackson extension to use it in an existing Quarkus application deployed in production.

In the Custom headers support section it's introduced the ClientHeadersFactory interface to allow injecting headers in a request, but you are forced to return a sync response. One can not use Uni<MultivaluedMap<String, String>>, which is of what is desired in my case, because I need to add a token in the header, and this token is retrieved by a request to another rest endpoint that returns a Uni<Token>.

How can I achieve this in the new implementation? If not possible, is there a workaround?

Answer 1

It's not possible to use Uni<MultivaluedMap<...>> in ClientHeadersFactory in Quarkus 2.2.x (and older versions). We may add such a feature in the near future.

Currently, you can @HeaderParam directly. Your code could probably look as follows:

Uni<String> token  = tokenService.getToken();
token.onItem().transformToUni(tokenValue -> client.doTheCall(tokenValue));

Where the client interface would be something like:

@Path("/")
public interface MyClient {

    @GET
    Uni<Foo> doTheCall(@HeaderParam("token") String tokenValue);

}