Mock configuration files

Syntactically, Mock configuration files are just Python files. But you should be rather conservative and use just the config_opts[] dictionary because we’d like to change the format in the future.

Mock RPM package self-documents all the available options, take a look at this file:

$ rpm -qd mock | grep site-defaults
/usr/share/doc/mock/site-defaults.cfg

Mock configuration files can be logically divided into generic (used for every executed Mock command) and chroot configuration (used only if the corresponding chroot is selected, see below).

Both the generic and chroot configuration can be done on either system level (/etc/mock directory) or on user level (files in $HOME/.config directory).

Selecting a chroot config

For example to initialize a Fedora Rawhide x86_64 chroot (using /etc/mock/fedora-rawhide-x86_64.cfg file), and switch into the chroot, one can do:

$ mock -r fedora-rawhide-x86_64 --shell

Note we are not using the .cfg suffix in the -r option in this case. This way the user level $HOME/.config files are searched for the corresponding .cfg file first, and since nothing is found, then the system level file is found in /etc/mock (and used).

One can though use a config pathname with the -r option, too. But the pathname must represent an existing file (accessible from the current working directory):

$ mock -r ./subdir/existing-config-file.cfg --shell
$ mock -r /etc/mock/fedora-35-x86_64.cfg

Generic configuration changes

Typically the file $HOME/.config/mock.cfg should be used for generic configuration changes for a single user. If a system Mock behavior change is desired (for all system users), then use /etc/mock/site-defaults.cfg.

The site-defaults.cfg is typically empty by default, but contains a basic documentation and a valid link to a complete configuration documentation. That documentation typically is /usr/share/doc/mock/site-defaults.cfg (location may vary depending on your host system conventions).

Chroot configuration changes

There are /etc/mock/<buildroot>.cfg files for various build chroots that contain various compatibility settings related to the target distribution (location of RPM repositories, if DNF or YUM should be used, working directory to be used, and so on).

These system files are shipped via the mock-core-configs (or other), and users are discouraged from changing these (change would break the automatic update of such file with an updated version of the package). It is safer to install an override configuration file:

$ cat $HOME/.config/mock/fedora-35-x86_64.cfg
# include the default configuration
include("/etc/mock/fedora-35-x86_64.cfg")
# install make into the minimal build chroot
config_opts['chroot_additional_packages'] = 'make'

You may also copy and edit an existing configuration file into a new one:

$ cp /etc/mock/fedora-rawhide-x86_64.cfg ~/.config/mock/foo.cfg

The default chroot configuration file is /etc/mock/default.cfg, which is usually a symlink to one of the installed chroot configuration files. You may create another symlink to an installed configuration file to change the default chroot config file:

$ ln -s /etc/mock/fedora-rawhide-x86_64.cfg ~/.config/mock/default.cfg

If Koji is already using a config you need, then you can use the Koji client tool for generating the file:

$ koji mock-config --tag f21-build --arch=aarch64 f21 > ~/.config/mock/foo.cfg

Similar functionality has the Copr client tool:

$ copr mock-config @copr/copr-dev fedora-21-x86_64 > ~/.config/mock/foo.cfg

When your file foo.cfg is installed, you can just do mock -r foo [...].

Order of loading the files

The order of reading and evaluating configuration files in Mock is the following:

1. /etc/mock/site-defaults.cfg
2. /etc/mock/<buildroot>.cfg or ~/.config/mock/<buildroot>.cfg
3. ~/.mock/user.cfg
4. ~/.config/mock.cfg (since mock-1.2.15)

I.e. the value set in the later configuration file overrides the value set by previously loaded files.