Let's say you wanted to install this plugin: https://github.com/finnlabs/openproject-meeting. Here is how you would do it with the openproject version packaged at https://pkgr.io/apps/tessi/openproject:
cat >> /opt/openproject/Gemfile.plugins <<EOF gem "openproject-plugins", :git => "https://github.com/opf/openproject-plugins.git", :branch => "stable" gem "openproject-meeting", :git => "https://github.com/finnlabs/openproject-meeting.git", :branch => "stable" EOF
sudo apt-get install -y git sudo openproject run bundle install --no-deployment sudo openproject run rake db:migrate sudo openproject run rake assets:precompile sudo service openproject restart
The plugins should now appear in the openproject UI.
Note that you will probably need to redo a
sudo openproject run bundle install --no-deployment on each upgrade of the openproject package.