Start with iRedMail
missing dependancies
apt-get install libcurl4-openssl-dev libsqlite3-dev
tutorial
https://github.com/gitlabhq/gitlabhq/wiki/V2.0-easy-setup-for-ubuntu
cd ruby-1.9.2-p290/ext/openssl/
sudo ruby extconf.rb
sudo make
sudo make install
./ubuntu_gitlab.sh