After writing the previous message, I realized that the nova.conf file which I had to use was actually /etc/nova/nova.conf. However, every time that I edited it and ran stack.sh, the sql_connection variable went empty again and again.
After writing the previous message, I realized that the nova.conf file which I had to use was actually /etc/nova/ nova.conf. However, every time that I edited it and ran stack.sh, the sql_connection variable went empty again and again.