After loosing a few hours reconfiguring xdebug, phpstorm and vagrant, I found this great ressource. Here are my notes about it:

phpstorm is installed on the hostmachine and the app is running in a vagrant box.

Vagrant guest machine setup

sudo apt-get install php5-xdebug

Edit /etc/php5/mods-available/xdebug.ini :

xdebug.remote_enable=true
xdebug.remote_connect_back=true
xdebug.idekey=MY_AWESOME_KEY

Phpstorm setup

Setup 'php remote debug' configuration

Setup 'server' configuration

Browser plugin

• install a browser plugin such as this one
• configure the ide key, here: MY_AWESOME_KEY
• it is also possible to use bookmarklets

Enjoy!

• Puts breakpoints
• Enable cookie using web browser extension or bookmarklet
• Click on the bug icon called 'debug mode'
• You can now enjoy the debugger (inspect variables, control the execution flow)