I am using Jenkins 2.319.1 with nginx as reverse proxy. There is a message in Jenkins that “it appears that your reverse proxy set up is broken”. I researched this problem quite a bit, and followed the usual steps to solve it (e.g. configure URL in Jenkins, set the proper headers in nginx).
The error is still showing, and I have the following lines in my jenkins.log file:
I was curious why the second URL seems to be incomplete, so I looked at Chrome’s network monitor to see how the reverse proxy test was being called. It turns out the second URL is passed to the function as a parameter in the URL, in my case it was:
Looking at the output, URI is already missing one slash after https, and in MESSAGE the URL completely cuts off after “https:”. I believe this is a parsing error somewhere in Jenkins, and the reason why the reverse proxy test fails even though everything seems to be configured correctly.
I think you’re missing something in your nginx reverse proxy configuration or in the Jenkins server name value. I’m using an nginx reverse proxy and I believe that ci.jenkins.io is also using an nginx proxy. Double check your nginx configuration.
However, I still can’t understand why the reverse proxy test Jenkins performs is behaving the way I described. I suspect there is a bug present. Why else would the URL get mangled this way and only appear as “https:” in my Jenkins logs?
I appreciate that you believe there is a bug present. However, that then leads me to wonder why hundreds (probably thousands) of Jenkins controllers around the world are running behind nginx proxies without seeing the bug, yet you are seeing the bug. If it is a bug in Jenkins, then it is a very distinctive bug with very specific conditions that cause it to only be visible to you.
Thanks for the help. I added X-Forwarded-Host to my nginx config. This didn’t help though, Jenkins is still complaining about a broken reverse proxy setup. Note that the message in the logs indicates that the inferred URL is parsed correctly from the various X-Forwarded Headers: