I was not able to get the user name passed from cosign to any services running with mod_proxy. Specifically I was testing on a rails app running on Thin and when dumping the environment variables nothing containing the user was present.
However I'd found this module this module which did make all of this work (mod-proxy-add-user). [1] It describes the header for REMOTE_USER not being set in the right phase. I didn't know what this meant, but it got it all to work. Would be nice to not need this extra module.
Anonymous