Load Balancer listener rule lost POST params

I don't think there's any good and supported way of passing POSTs between applications with HTTP redirects. Your application code or the form POST action in your application should call or point to the other application's URL if a request is to be made from the client to the other application, without passing through the first application.

Thanks Leo K,

The idea is that the application points to the new beanstalk "B" for those requests... but until all the users have the new version I want to redirect the traffic from that webservice (in beanstalk "A") to the new beanstalk "B", and I would like to do it from the balancer to avoid consumption in beanstalk "A".

If the load balancer sitting in front of the environment "A" can also reach "B", perhaps you could configure a listener rule to send requests for the URL paths where the POST requests are sent in application "A" to the corresponding URL in "B"? The main limitations would be that the URLs (including hostnames) would have to match in environments "A" and "B", because an ALB isn't able to rewrite requests, and that the same load balancer would have to have connectivity to A and B.