Nova has a myriad of configuration options due to its wide support of differing technologies, products, and architectures. This section gives you an overview of the most important configuration options, as well as important administrative commands to bend Nova to your will.
Nova daemons are given configuration options on startup through a set of flags usually set in text file. Traditionally, this file is located at /etc/nova.conf. However, these flags can also be set directly on the command line or in an alternate configuration file that is designated at run time.
To use an alternate configuration file with the a Nova daemon, simply make the file path the argument to the --flagfile=/path/to/altnova.conf flag. To pass arbitrary flags on the command line, simply include them and they will override the values in the configuration file.
The /etc/nova.conf file is a very simple format: put each flag on a separate line, with no comments or other characters. Here is an example of a minimal /etc/nova.conf file:
--sql_connection=mysql://root:nova@localhost/nova --auth_driver=nova.auth.dbdriver.DbDriver --daemonize=1 --fixed_range=172.16.0.0/24 --network_size=32
One of the weaknesses of Nova is that the /etc/nova.conf does not not support comments. All lines in the file are evaluated. As such, it does not include any helpful configuration comments that you might see in other open source packages.
The most complete list of Nova configuration flags is maintained at http://wiki.openstack.org/FlagsGrouping. Please note that this last sentence said “most complete,” not “definitive.” The definitive source of all configuration flags is the Nova source code.