First access to a Pass-Through proxy change POST into GET
I have an application configured as pass-through proxy (https://app1)
Some client needs to acess this application to send POST requests to https://app1/process.php.
But if the client is not yet authenticated or is authenticated but did access yet https://app1 in the current session, the PCS respond with a 302 redirect to /dana/auth/launch.cgi, then potentially the login page, then a few more 302 redirects before the redirection to the original https://app1/process/php.
In the meantime, the method is changed into a GET and the original POST parameters are lost.
A workaround would be to ask the users to access https://app1/ first but it's not possible in every case.
Is there any way to make this work? To be able to do POST as first request to a pass-through proxy site?