Unable to Intercept Envelope Headers Before RabbitMQ Transport Execution in Wolverine with InvokeAsync Operation

[adarshanadig]

Hi Team,
I’m trying to capture envelope message details such as CorrelationId and also add additional information to the header (like user credentials and other metadata). However, I’m unable to achieve this. I’ve tried using middleware, IEnvelopeRule, and IRabbitMqEnvelopeMapper, but none of these seem to be triggered once InvokeAsync is called, before the execution reaches the RabbitMQ transport layer.

am using latest version 5.4.0 . Any suggestion please

Below are client side configuration tried
builder.UseWolverine(static opts =>
{
opts.Discovery
// Turn off the default handler conventions altogether
.DisableConventionalDiscovery();

 opts.Services.AddLogging(x => x.AddConsole());

 opts.UseRabbitMq($"amqp://{UserName}:{Password}@{HostName}:{Port}{VirtualHost}")
     .AutoProvision() // Let Wolverine auto-provision queues and exchanges
     .DisableDeadLetterQueueing() // Explicitly disable dead letter queues to avoid conflicts
     .UseConventionalRouting().
     ConfigureSenders(s => 
         s.CustomizeOutgoing(x =>
         {
             Console.WriteLine("[ClientProgram] Configuring outgoing envelope customization for RabbitMQ sender");

         }).AddOutgoingRule(new EnvelopeInterceptRule()));

 opts.Policies.AddMiddleware(typeof(EnvelopHanlingMiddleware));

});

and Middleware and IEnvlopeRule and IRabbitMqEnvelopeMapper implementionation are below

public class EnvelopeInterceptRule : IEnvelopeRule
{

 public void Modify(Envelope envelope)
 {
     Console.WriteLine("MAPPER CALLED (outgoing)");
 }

}

public class EnvelopHanlingMiddleware
{
public async Task BeforeAsync(
Envelope envelope,
Func next)
{
Console.WriteLine("Entered into middleware");
await next();
}

}

public class CustomRabbitMqMapper : IRabbitMqEnvelopeMapper
{
public void MapEnvelopeToOutgoing(Envelope envelope, IBasicProperties props)
{
Console.WriteLine("MAPPER CALLED (outgoing)");

     props.Headers ??= new Dictionary<string, object>();
     props.Headers["x-test"] = "ok";
 }


 public void MapIncomingToEnvelope(Envelope envelope, IReadOnlyBasicProperties incoming)
 {
     Console.WriteLine("MAPPER CALLED (incoming)");
 }

}

[theobailey133]

Same issue on my side (with azure service bus, rather than rabbitmq) so the issue seems to be transport agnostic. my findings were metadatarules only works on fire and forget events. Anything with a response (invoke) does not use metadatarules. It looks like a design decision, perhaps the documentation would benefit from mentioning this limitation with metadata rules.

My workaround for this was to make my own static extension method on IServiceBus which adds the common headers I need to use. Then just swap all invoke calls over to my own extension method. The next bit is a bit extra, but you can setup a roslyn analyzer to give compile errors/warnings on usage of invoke/invokefortenant and point to your extension method instead for added safety.