I tried to use mod_proxy to forward requests from http://server/jenkins to http://server:8080 (as per https://wiki.jenkins-ci.org/display/JENKINS/Running+Jenkins+behind+Apache?focusedCommentId=63146343#comment-63146343). This worked fine for the most part except that the CAS plugin (https://wiki.jenkins-ci.org/display/JENKINS/CAS+Plugin CAS plugin) appears to forget the /jenkins prefix when returning from authentication.

For example, when I visit http://server/jenkins/ I'm correctly forwarded to our CAS login page, but when I'm redirected back to Jenkins, the URL is something like http://server:8080/securityRealm/finishLogin?ticket=... (it's missing the /jenkins prefix). I believe it should be http://server:8080/jenkins/securityRealm/finishLogin?ticket=....

In fact, when I manually modify the URL to include /jenkins (after being erroneously forwarded to the wrong address) the login is successful and I can interact with Jenkins normally.

If I don't use mod_proxy (and visit http://server:8080 directly) the CAS plugin works well.