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Mock is a tool for building packages. It can build packages for different architectures and different Fedora, RHEL, and Mageia versions than the build host has. Mock creates chroots and builds packages in them. Its only task is to reliably populate a chroot and attempt to build a package in that chroot.
Mock also offers a multi-package tool, mockchain, that can build chains of packages that depend on each other.
Mock is capable of building SRPMs from source configuration management if the mock-scm package is present, then building the SRPM into RPMs. See --scm-enable in the documentation.
Tar balls can be found at: https://fedorahosted.org/releases/m/o/mock/
If you want to contribute to code, please checkout https://github.com/rpm-software-management/mock for more informations.
Otherwise just run
dnf install mock
All users that are to use mock must be added to the mock group.
usermod -a -G mock [User name]
Mock is running some parts of code under root privileges. There are known ways how to get root access once user is in mock group (and once he is able to run mock). This is possible when user abuse the mock configuration options. Please do not add anyone who is not trustworthy to the mock group!
Configuration files are in
/etc/mock. Mock versions 0.8.0 and higher cache the downloaded rpm packages (via the yum_cache plugin), which speeds up subsequent builds by a considerable margin. Nevertheless, you may wish to change the default configuration to point to local repositories to speed up builds.
By default, builds are done in
/var/lib/mock, so be sure you have room. Starting with mock 0.8.0 and higher, you can change this via the 'basedir' config option.
- bind_mount - bind mountpoints inside the chroot
- ccache - compiler cache plugin
- chroot_scan - allows you to retrieve build artifacts from buildroot (e.g. additional logs, coredumps)
- compress_logs - compress logs
- hw_info - prints HW information of builder
- lvm_root - caching buildroots using LVM
- mount - allows you to mount directories into chroot
- package_state - dumps list of available and installed packages
- pm_request - Executes package manager commands requested by processes runninng in the chroot.
- root_cache - cache buildroots (as tar file).
- scm - SCM integration module - builds directly from Git or Svn.
- selinux - on SELinux enabled box, this plugin will pretend, that SELinux is disabled in build environment.
- sign - call command on the produced rpm.
- tmpfs - mount buildroot directory as tmpfs
yum_cache - mount
/var/cache/yumof your machine to chroot
Plugins can be enabled on command line e.g
--enable-plugin=chroot_scan. And you can set plugin options using e.g.
One of the reasons why mock has always been quite slow is because installing a lot of packages generates heavy IO load. But the main bottleneck regarding IO is not unpacking files from packages to disk but writing Yum DB entries. Yum DB access (used by both yum and dnf) generates a lot of
fsync(2) calls. Those don't really make sense in mock because people generally don't try to recover mock buildroots after hardware failure. We discovered that getting rid of fsync improves the package installation speed by almost a factor of 4. Mikolaj Izdebski developed small C library 'nosync' that is LD_PRELOADed and replaces fsync family of calls with (almost) empty implementations. I added support for it in mock.
How to activate it?
You need to install
nosync package (available in rawhide) and for multilib systems (x86_64) you need version for both architectures. Then it can be enabled in mock by setting
config_opts['nosync'] = True
It is requires those extra steps to set up but it really pays off quickly.
Using Mock outside your git sandbox
Create your SRPM using
rpmbuild -bs. Then change to the directory where your srpm was created.
Now you can start mock with
mock -r <configname> rebuild package-1.2-3.src.rpm
where is the name of a configuration from
/etc/mock/, without the
/etc/mock path prefix and without the .cfg suffix.
Note that you can track the progress of mock using the logs stored in
Mock inside Docker
Since version 1.3.2 you can run mock inside of Docker. However you need to add SYS_ADMIN to docker container. I.e. run:
docker run --cap-add=SYS_ADMIN ...
Please note, that Mock inside of Docker skips unsharing of namespace, so it run in the same namespace as other program in the same container. You should not run any other application inside of that container. Mock print warning about this. You can suppress this warning, when you put in config
config_opts['docker_unshare_warning'] = False
Mock on EL 6 and EL 7: Yum, and DNF
Starting with the Fedora 24 builds, Mock requires DNF to run properly. Since not all parts of DNF are available on EL 6 and EL 7, Mock cannot be run there with the default configuration.
There are however two workarounds available:
- For one time runs it is possible to pass
--yumas an option on the command line.
To make yum the default package manager, a change in
/etc/mock/site-defaults.cfgor inside of any
/etc/mock/*.cfgfile is necessary:
config_opts['package_manager'] = 'yum'
For more information, please see the blog entry by Miroslav Suchý.
See separate page: FAQ
Mock have various exist codes to signalize problem in build. See https://github.com/rpm-software-management/mock/blob/master/py/mockbuild/exception.py#L26
Generate custom config file
Mock main config file is
/etc/mock/site-defaults.cfg, which contains all defaults setting and all possible variables you can change.
Then you have
/etc/mock/<buildroot>.cfg for various buildroots, which contains settings for yum/dnf which are for various distribution different.
When you want to alter the config you may copy one and edit it manually, however if koji is already using such an config, then you can use
mock-config --help for information how to generate one. E.g.:
koji mock-config --tag f21-build --arch=aarch64 f21
You should not alter
site-defaults.cfg unless you want to change settings for all users. You should put your changes to
~/.mock/user.cfg or to
The order of reading and evaluating configuration files is:
- ~/.config/mock.cfg (since mock-1.2.15)