How can I get Gitlab 6.5 to show its icons under a Apache 2.4 proxy?

Question 1

Since it is under a relative root, you still would need to run the following as noted above in order to verify the correct mapping of the assets (which includes icons and CSS URLs):

sudo -u git -H bundle exec rake assets:precompile RAILS_ENV=production RAILS_RELATIVE_URL_ROOT=/gitlab

For you non-relative URL users, leave off the extra relative URL portion

sudo -u git -H bundle exec rake assets:precompile RAILS_ENV=production

You can also restart as noted by @LpLrich :

sudo service gitlab restart

For some older Linux setups instead use:

sudo /etc/init.d/gitlab restart

Then refresh your browser.

Yet none of the above steps worked on my system because, as best as I can say, imperfect Apache setup which I fixed below--including it in case you are finding the same issue of fixing Gitlab correctly but finding the end result failing in the browser. I did change to not using the relative URL root anymore but that doesn't matter so much. This should help Apache fix the issue above as well once the gitlab steps are completed. Sorry, the ProxyPassReverse is the main change you need to notice from the question's Apache setup:

<IfModule mod_ssl.c>
<VirtualHost *:443>
  Servername gitlab.my_domain.com
  ServerAdmin my_admin@my_domain.com

  SSLCertificateFile /etc/apache2/ssl.crt/gitlab_my_domain.crt
  SSLCertificateKeyFile /etc/apache2/ssl.crt/gitlab_my_domain_private.key
  SSLCACertificateFile /etc/apache2/ssl.crt/gitlab.ca-bundle

  ##### All the other Apache SSL setup skipped here for StackOverflow ####

  ProxyPreserveHost On

  <Location />
    # New authorization commands for apache 2.4 and up
    # http://httpd.apache.org/docs/2.4/upgrading.html#access
    Require all granted

    # For relative URL root "host:your_gitlab_port/relative_root"
    #ProxyPassReverse http://127.0.0.1:8080/gitlab
    #ProxyPassReverse https://gitlab.my_domain.com/gitlab

    # For non-relative URL root
    ProxyPassReverse http://127.0.0.1:8080
    ProxyPassReverse https://gitlab.my_domain.com/
  </Location>

  # apache equivalent of nginx try files
  # http://serverfault.com/questions/290784/what-is-apaches-equivalent-of-nginxs-try-files
  # http://stackoverflow.com/questions/10954516/apache2-proxypass-for-rails-app-gitlab
  RewriteEngine on
  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
  RewriteRule .* http://127.0.0.1:8080%{REQUEST_URI} [P,QSA]
  RequestHeader set X_FORWARDED_PROTO 'https'

  # needed for downloading attachments
  DocumentRoot /home/git/gitlab/public

  #Set up apache error documents, if back end goes down (i.e. 503 error) then a maintenance/deploy page is thrown up.
  ErrorDocument 404 /404.html
  ErrorDocument 422 /422.html
  ErrorDocument 500 /500.html
  ErrorDocument 503 /deploy.html

  LogFormat  "%{X-Forwarded-For}i %l %u %t \"%r\" %>s %b" common_forwarded
  ErrorLog      /var/log/apache2/gitlab-ssl_error.log
  CustomLog /var/log/apache2/gitlab-ssl_forwarded.log common_forwarded
  CustomLog /var/log/apache2/gitlab-ssl_access.log combined env=!dontlog
  CustomLog /var/log/apache2/gitlab-ssl.log combined
</VirtualHost>
</IfModule>

(from https://github.com/gitlabhq/gitlab-recipes/blob/master/web-server/apache/gitlab-ssl-apache2.4.conf)

Question 2

This might help you,

https://github.com/gitlabhq/gitlabhq/issues/3306#issuecomment-15971720

Basically it's saying to run a rake assets:clean and then a assets:precompile and then a service gitlab restart

I had precompiled my assets, checked the public/assets folder and could see they existed but some icons were not showing so I cleaned them out, precompiled again and restarted it then they started showing up.

Run

sudo -u git -H bundle exec rake assets:clean RAILS_ENV=production

Then

sudo -u git -H bundle exec rake assets:precompile RAILS_ENV=production RAILS_RELATIVE_URL_ROOT=/gitlab

And refresh the page, if it's not working try

sudo service gitlab restart

But I looked in my history there now and I couldn't see myself restarting it so I am assuming that when this happened to me I simply cleaned them out and precompiled them again and I didn't have to restart.