Installing a locally compiled google-protobuf gem

First we must find the exact version of google-protobuf that your GitLab installation requires.

cd /home/git/gitlab

# Only one of the following two commands will print something. It
# will look like: * google-protobuf (3.2.0)
bundle list | grep google-protobuf
bundle check | grep google-protobuf

Below we use 3.2.0 as an example. Replace it with the version number you found above.

cd /home/git/gitlab
sudo -u git -H gem install google-protobuf --version 3.2.0 --platform ruby

Finally, you can test whether google-protobuf loads correctly. The following should print 'OK'.

sudo -u git -H bundle exec ruby -rgoogle/protobuf -e 'puts :OK'

If the gem install command fails you may need to install developer tools. On Debian: apt-get install build-essential libgmp-dev, on Centos/RedHat yum groupinstall 'Development Tools'.