A simple solution to authenticate users in Jira via X-Remote-User header that still works with JIRA 11 and the switch to Jakarta.
This is a current version of: https://github.com/Fuchs/jira-remote-user-sso.
There is also a plugin on the marketplace that does this (not developed by me): https://marketplace.atlassian.com/apps/1221625/http-header-authentication-for-jira. So if you really want this and need something supported you should probably use that.
IMPORTANT: You probably don't want to use that because it is potentially very insecure (headers can be faked). If you use this you must ensure that all traffic has to go through the reverse proxy that sets the
X-Remote-Userheader and that the Jira port can't be called without going through the reverse proxy. Also you will need to ensure that the reverse proxy will drop anyX-Remote-Userheader that is being sent to it. **You proably want to use [SSO for Atlassian Data Center](https://marketplace.atlassian.com/apps/1216096/sso-for-atlassian-data-c