Impossible de construire l'application en production - mysql2

I wrote a plugin which uses the mysql2 gem. The rebuilding of app fails with the error:

mysql client is missing. You may need to 'apt-get install libmysqlclient-dev' or 'yum install mysql-devel', and try again.

What do I need to do to get past this ? How do I run apt-get install libmysqlclient-dev before the gem is installed ?

I have edited app.yml to include the command apt-get install libmysqlclient-dev in the after_code section. Hope that works.

Edit: It worked!