149 lines
6.1 KiB
ReStructuredText
149 lines
6.1 KiB
ReStructuredText
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Lorax
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=====
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:Authors:
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Brian C. Lane <bcl@redhat.com>
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"I am the Lorax. I speak for the trees [and images]."
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The `lorax <https://github.com/rhinstaller/lorax>`_ tool is used to create the
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`Anaconda <https://github.com/rhinstaller/anaconda>`_ installer boot.iso as
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well as the basic release tree, and .treeinfo metadata file. Its dependencies
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are fairly light-weight because it needs to be able to run in a mock chroot
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environment. It is best to run lorax from the same release as is being targeted
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because the templates may have release specific logic in them. eg. Use the
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rawhide version to build the boot.iso for rawhide, along with the rawhide
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repositories.
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lorax cmdline arguments
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-----------------------
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See the output from ``lorax --help`` for the commandline arguments.
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Quickstart
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----------
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Run this as root to create a boot.iso in ``./results/``::
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yum install lorax
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setenforce 0
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lorax -p RHEL -v 7 -r 7 \
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-s http://mirror.centos.org/centos-7/7/os/x86_64/ \
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-s http://mirror.centos.org/centos-7/7/updates/x86_64/ \
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./results/
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setenforce 1
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You can add your own repos with ``-s`` and packages with higher NVRs will
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override the ones in the distribution repositories.
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Under ``./results/`` will be the release tree files: .discinfo, .treeinfo, everything that
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goes onto the boot.iso, the pxeboot directory, and the boot.iso under ``./images/``.
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Running inside of mock
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----------------------
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If you are using lorax with mock v1.3.4 or later you will need to pass
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``--old-chroot`` to mock. Mock now defaults to using systemd-nspawn which cannot
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create the needed loop device nodes. Passing ``--old-chroot`` will use the old
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system where ``/dev/loop*`` is setup for you.
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How it works
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------------
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Lorax uses `yum <https://github.com/rpm-software-management/yum>`_ to install
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packages into a temporary directory, sets up configuration files, it then
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removes unneeded files to save space, and creates a squashfs filesystem of the
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files. The iso is then built using a generic initramfs and the kernel from the
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selected repositories.
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To drive these processes Lorax uses a custom template system, based on `Mako
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templates <http://www.makotemplates.org/>`_ with the addition of custom
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commands (documented in :class:`pylorax.ltmpl.LoraxTemplateRunner`). Mako
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supports ``%if/%endif`` blocks as well as free-form python code inside ``<%
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%>`` tags and variable substitution with ``${}``. The default templates are
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shipped with lorax in ``/usr/share/lorax/`` and use the
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``.tmpl`` extension.
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runtime-install.tmpl
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~~~~~~~~~~~~~~~~~~~~
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The ``runtime-install.tmpl`` template lists packages to be installed using the
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``installpkg`` command. This template is fairly simple, installing common packages and
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architecture specific packages. It must end with the ``run_pkg_transaction``
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command which tells dnf to download and install the packages.
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runtime-postinstall.tmpl
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~~~~~~~~~~~~~~~~~~~~~~~~
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The ``runtime-postinstall.tmpl`` template is where the system configuration
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happens. The installer environment is similar to a normal running system, but
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needs some special handling. Configuration files are setup, systemd is told to
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start the anaconda.target instead of a default system target, and a number of
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unneeded services are disabled, some of which can interfere with the
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installation. A number of template commands are used here:
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* :func:`append <pylorax.ltmpl.LoraxTemplateRunner.append>` to add text to a file.
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* :func:`chmod <pylorax.ltmpl.LoraxTemplateRunner.chmod>` changes the file's mode.
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* :func:`gconfset <pylorax.ltmpl.LoraxTemplateRunner.gconfset>` runs gconfset.
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* :func:`install <pylorax.ltmpl.LoraxTemplateRunner.install>` to install a file into the installroot.
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* :func:`mkdir <pylorax.ltmpl.LoraxTemplateRunner.mkdir>` makes a new directory.
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* :func:`move <pylorax.ltmpl.LoraxTemplateRunner.move>` to move a file into the installroot
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* :func:`replace <pylorax.ltmpl.LoraxTemplateRunner.replace>` does text substitution in a file
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* :func:`remove <pylorax.ltmpl.LoraxTemplateRunner.remove>` deletes a file
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* :func:`runcmd <pylorax.ltmpl.LoraxTemplateRunner.runcmd>` run arbitrary commands.
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* :func:`symlink <pylorax.ltmpl.LoraxTemplateRunner.symlink>` creates a symlink
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* :func:`systemctl <pylorax.ltmpl.LoraxTemplateRunner.systemctl>` runs systemctl in the installroot
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runtime-cleanup.tmpl
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~~~~~~~~~~~~~~~~~~~~
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The ``runtime-cleanup.tmpl`` template is used to remove files that aren't strictly needed
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by the installation environment. In addition to the ``remove`` template command it uses:
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* :func:`removepkg <pylorax.ltmpl.LoraxTemplateRunner.removepkg>`
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remove all of a specific package's contents. A package may be pulled in as a dependency, but
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not really used. eg. sound support.
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* :func:`removefrom <pylorax.ltmpl.LoraxTemplateRunner.removefrom>`
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Removes some files from a package. A file glob can be used, or the --allbut option to
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remove everything except a select few.
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* :func:`removekmod <pylorax.ltmpl.LoraxTemplateRunner.removekmod>`
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Removes kernel modules
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The squashfs filesystem
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~~~~~~~~~~~~~~~~~~~~~~~
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After ``runtime-*.tmpl`` templates have finished their work lorax creates an
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empty ext4 filesystem, copies the remaining files to it, and makes a squashfs
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filesystem of it. This file is the / of the boot.iso's installer environment
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and is what is in the LiveOS/squashfs.img file on the iso.
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iso creation
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~~~~~~~~~~~~
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The iso creation is handled by another set of templates. The one used depends
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on the architecture that the iso is being created for. They are also stored in
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``/usr/share/lorax/`` and are named after the arch, like
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``x86.tmpl`` and ``aarch64.tmpl``. They handle creation of the tree, copying
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configuration template files, configuration variable substitution, treeinfo
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metadata (via the :func:`treeinfo <pylorax.ltmpl.LoraxTemplateRunner.treeinfo>`
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template command). Kernel and initrd are copied from the installroot to their
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final locations and then mkisofs is run to create the boot.iso
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Custom Templates
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----------------
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The default set of templates and configuration files are shipped in the
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``/usr/share/lorax/`` directory. You can make a copy of them and place them
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into another directory and then select the new template directory by passing
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``--sharedir`` to lorax.
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