Change Gitlab homepage using Apache’s mod_rewrite

For some time I have been looking for a way to share public projects easily using GitLab. With the Public Project option of GitLab this was already possible for some time, but it did not work quite as I would like to (i.e. I would like http://gitlab.mydomain.tld to be the URL for all public projects). Due to the way GitLab is setup, the default URL will redirect the user to the login page, which does provide a link to the Public Projects page, but was not quite what I want.

Of course, as GitLab is open source, I could change the code directly, but as I would have to do that after each upgrade of GitLab (which is monthly!) I did not want to do that. Today I found a way around changing the code by using the following mod_rewrite rules to my Apache configuration (I placed this in the <VirtualHost> configuration but should also work from a .htaccess file):

# Redirect /users/sign_in to /public unless it has a local refferer
# This makes the public projects page the homepage instead of the login page
RewriteCond   %{HTTP_HOST}@@%{HTTP_REFERER}    !^([^@]*)@@https?://1/
RewriteRule   ^/users/sign_in$                 https://%{SERVER_NAME}/public/          [R,L]

This is inspired by a blog post on referer checking from the Apache .htaccess file. To get to this solution I just had to realize that an internal redirect by the application clears the referrer and apply the opposite logic to intervene when this happened (no referrer implies a redirect, when the user clicks on a link the request will have a referrer). How this works is:

1. The user visits http://gitlab.mydomain.tld/
2. GitLab redirects this request to its sign_in page
3. The browser requests the sign_in page, as this was a redirected page the referrer will be empty
4. The above mod_rewrite rule kicks in and redirects the user to the public projects page

For me this setup works as I expect. The only caveats are that users with browsers setup not to provide a referrer (e.g. for privacy reasons) may no longer be able to login and that a direct link to the sign_in page won’t work (the user will be redirected to the public projects page and has to click the sign_in button). For my setup both are no issue, let me know through the comments if there are other issues or perhaps solutions for this.