6. User Guide

6.6. API

Cobbler also makes itself available as an XML-RPC API for use by higher level management software. Learn more at https://cobbler.github.io

6.7. Triggers

Triggers provide a way to integrate Cobbler with arbitrary 3rd party software without modifying Cobbler’s code. When adding a distro, profile, system, or repo, all scripts in /var/lib/cobbler/triggers/add are executed for the particular object type. Each particular file must be executable and it is executed with the name of the item being added as a parameter. Deletions work similarly – delete triggers live in /var/lib/cobbler/triggers/delete. Order of execution is arbitrary, and Cobbler does not ship with any triggers by default. There are also other kinds of triggers – these are described on the Cobbler Wiki. For larger configurations, triggers should be written in Python – in which case they are installed differently. This is also documented on the Wiki.

6.8. Images

Cobbler can help with booting images physically and virtually, though the usage of these commands varies substantially by the type of image. Non-image based deployments are generally easier to work with and lead to more sustainable infrastructure. Some manual use of other commands beyond of what is typically required of Cobbler may be needed to prepare images for use with this feature.

6.9. Power Management

Cobbler contains a power management feature that allows the user to associate system records in Cobbler with the power management configuration attached to them. This can ease installation by making it easy to reassign systems to new operating systems and then reboot those systems.

6.10. Non-import (manual) workflow

The following example uses a local kernel and initrd file (already downloaded), and shows how profiles would be created using two different automatic installation files – one for a web server configuration and one for a database server. Then, a machine is assigned to each profile.

cobbler check
cobbler distro add --name=rhel4u3 --kernel=/dir1/vmlinuz --initrd=/dir1/initrd.img
cobbler distro add --name=fc5 --kernel=/dir2/vmlinuz --initrd=/dir2/initrd.img
cobbler profile add --name=fc5webservers --distro=fc5-i386 --autoinstall=/dir4/kick.ks --kernel-options="something_to_make_my_gfx_card_work=42 some_other_parameter=foo"
cobbler profile add --name=rhel4u3dbservers --distro=rhel4u3 --autoinstall=/dir5/kick.ks
cobbler system add --name=AA:BB:CC:DD:EE:FF --profile=fc5-webservers
cobbler system add --name=AA:BB:CC:DD:EE:FE --profile=rhel4u3-dbservers
cobbler report

6.11. Repository Management


This has already been covered a good bit in the command reference section.

Yum repository management is an optional feature, and is not required to provision through Cobbler. However, if Cobbler is configured to mirror certain repositories, it can then be used to associate profiles with those repositories. Systems installed under those profiles will then be autoconfigured to use these repository mirrors in /etc/yum.repos.d, and if supported (Fedora Core 6 and later) these repositories can be leveraged even within Anaconda. This can be useful if (A) you have a large install base, (B) you want fast installation and upgrades for your systems, or (C) have some extra software not in a standard repository but want provisioned systems to know about that repository.

Make sure there is plenty of space in Cobbler’s webdir, which defaults to /var/www/cobbler.

cobbler reposync [--only=ONLY] [--tries=N] [--no-fail]

Cobbler reposync is the command to use to update repos as configured with “cobbler repo add”. Mirroring can take a long time, and usage of Cobbler reposync prior to usage is needed to ensure provisioned systems have the files they need to actually use the mirrored repositories. If you just add repos and never run “cobbler reposync”, the repos will never be mirrored. This is probably a command you would want to put on a crontab, though the frequency of that crontab and where the output goes is left up to the systems administrator.

For those familiar with dnf’s reposync, Cobbler’s reposync is (in most uses) a wrapper around the dnf reposync command. Please use “cobbler reposync” to update Cobbler mirrors, as dnf’s reposync does not perform all required steps. Also Cobbler adds support for rsync and SSH locations, where as dnf’s reposync only supports what yum supports (http/ftp).

If you ever want to update a certain repository you can run:

cobbler reposync --only="reponame1" ...

When updating repos by name, a repo will be updated even if it is set to be not updated during a regular reposync operation (ex: cobbler repo edit --name=reponame1 --keep-updated=False).

Note that if a Cobbler import provides enough information to use the boot server as a yum mirror for core packages, Cobbler can set up automatic installation files to use the Cobbler server as a mirror instead of the outside world. If this feature is desirable, it can be turned on by setting yum_post_install_mirror to True in /etc/cobbler/settings.yaml (and running cobbler sync). You should not use this feature if machines are provisioned on a different VLAN/network than production, or if you are provisioning laptops that will want to acquire updates on multiple networks.

The flags --tries=N (for example, --tries=3) and --no-fail should likely be used when putting reposync on a crontab. They ensure network glitches in one repo can be retried and also that a failure to synchronize one repo does not stop other repositories from being synchronized.

6.11.2. Importing trees

Cobbler can auto-add distributions and profiles from remote sources, whether this is a filesystem path or an rsync mirror. This can save a lot of time when setting up a new provisioning environment. Import is a feature that many users will want to take advantage of, and is very simple to use.

After an import is run, Cobbler will try to detect the distribution type and automatically assign automatic installation files. By default, it will provision the system by erasing the hard drive, setting up eth0 for DHCP, and using a default password of “cobbler”. If this is undesirable, edit the automatic installation files in /etc/cobbler to do something else or change the automatic installation setting after Cobbler creates the profile.

Mirrored content is saved automatically in /var/www/cobbler/distro_mirror.

Example 1: cobbler import --path=rsync://mirrorserver.example.com/path/ --name=fedora --arch=x86

Example 2: cobbler import --path=root@ --name=bar

Example 3: cobbler import --path=/mnt/dvd --name=baz --arch=x86_64

Example 4: cobbler import --path=/path/to/stuff --name=glorp

Example 5: cobbler import --path=/path/where/filer/is/mounted --name=anyname --available-as=nfs://nfs.example.org:/where/mounted/

Once imported, run a cobbler list or cobbler report to see what you’ve added.

By default, the rsync operations will exclude content of certain architectures, debug RPMs, and ISO images – to change what is excluded during an import, see /etc/cobbler/rsync.exclude.

Note that all of the import commands will mirror install tree content into /var/www/cobbler unless a network accessible location is given with --available-as. –available-as will be primarily used when importing distros stored on an external NAS box, or potentially on another partition on the same machine that is already accessible via http:// or ftp://.

For import methods using rsync, additional flags can be passed to rsync with the option --rsync-flags.

Should you want to force the usage of a specific Cobbler automatic installation template for all profiles created by an import, you can feed the option --autoinstall to import, to bypass the built-in automatic installation file auto-detection.

6.11.3. Repository mirroring workflow

The following example shows how to set up a repo mirror for all enabled Cobbler host repositories and two additional repositories, and create a profile that will auto install those repository configurations on provisioned systems using that profile.

cobbler check
# set up your cobbler distros here.
cobbler autoadd
cobbler repo add --mirror=http://mirrors.kernel.org/fedora/core/updates/6/i386/ --name=fc6i386updates
cobbler repo add --mirror=http://mirrors.kernel.org/fedora/extras/6/i386/ --name=fc6i386extras
cobbler reposync
cobbler profile add --name=p1 --distro=existing_distro_name --autoinstall=/etc/cobbler/kickstart_fc6.ks --repos="fc6i386updates fc6i386extras"

6.11.4. Import Workflow

Import is a very useful command that makes starting out with Cobbler very quick and easy.

This example shows how to create a provisioning infrastructure from a distribution mirror or DVD ISO. Then a default PXE configuration is created, so that by default systems will PXE boot into a fully automated install process for that distribution.

You can use a network rsync mirror, a mounted DVD location, or a tree you have available via a network filesystem.

Import knows how to autodetect the architecture of what is being imported, though to make sure things are named correctly, it’s always a good idea to specify --arch. For instance, if you import a distribution named “fedora8” from an ISO, and it’s an x86_64 ISO, specify --arch=x86_64 and the distro will be named “fedora8-x86_64” automatically, and the right architecture field will also be set on the distribution object. If you are batch importing an entire mirror (containing multiple distributions and arches), you don’t have to do this, as Cobbler will set the names for things based on the paths it finds.

cobbler check
cobbler import --path=rsync://yourfavoritemirror.com/rhel/5/os/x86_64 --name=rhel5 --arch=x86_64
# OR
cobbler import --path=/mnt/dvd --name=rhel5 --arch=x86_64
# OR (using an external NAS box without mirroring)
cobbler import --path=/path/where/filer/is/mounted --name=anyname --available-as=nfs://nfs.example.org:/where/mounted/
# wait for mirror to rsync...
cobbler report
cobbler system add --name=default --profile=name_of_a_profile1
cobbler system add --name=AA:BB:CC:DD:EE:FF --profile=name_of_a_profile2
cobbler sync

6.12. Virtualization

For Virt, be sure the distro uses the correct kernel (if paravirt) and follow similar steps as above, adding additional parameters as desired:

cobbler distro add --name=fc7virt [options...]

Specify reasonable values for the Virt image size (in GB) and RAM requirements (in MB):

cobbler profile add --name=virtwebservers --distro=fc7virt --autoinstall=path --virt-file-size=10 --virt-ram=512 [...]

Define systems if desired. Koan can also provision based on the profile name.

cobbler system add --name=AA:BB:CC:DD:EE:FE --profile=virtwebservers [...]

If you have just installed Cobbler, be sure that the cobblerd service is running and that port 25151 is unblocked.

See the manpage for Koan for the client side steps.

6.13. Autoinstallation

6.13.1. Automatic installation templating

The --autoinstall_meta options above require more explanation.

If and only if --autoinstall options reference filesystem URLs, --autoinstall-meta allows for templating of the automatic installation files to achieve advanced functions. If the --autoinstall-meta option for a profile read --autoinstall-meta="foo=7 bar=llama", anywhere in the automatic installation file where the string $bar appeared would be replaced with the string “llama”.

To apply these changes, cobbler sync must be run to generate custom automatic installation files for each profile/system.

For NFS and HTTP automatic installation file URLs, the --autoinstall_meta options will have no effect. This is a good reason to let Cobbler manage your automatic installation files, though the URL functionality is provided for integration with legacy infrastructure, possibly including web apps that already generate automatic installation files.

Templated automatic files are processed by the templating program/package Cheetah, so anything you can do in a Cheetah template can be done to an automatic installation template. Learn more at https://cheetahtemplate.org/users_guide/intro.html

When working with Cheetah, be sure to escape any shell macros that look like $(this) with something like \$(this) or errors may show up during the sync process.

The Cobbler Wiki also contains numerous Cheetah examples that should prove useful in using this feature.

Also useful is the following repository: https://github.com/FlossWare/cobbler

6.13.2. Automatic installation snippets

Anywhere a automatic installation template mentions SNIPPET::snippet_name, the file named /var/lib/cobbler/snippets/snippet_name (if present) will be included automatically in the automatic installation template. This serves as a way to recycle frequently used automatic installation snippets without duplication. Snippets can contain templating variables, and the variables will be evaluated according to the profile and/or system as one would expect.

Snippets can also be overridden for specific profile names or system names. This is described on the Cobbler Wiki.

6.13.3. Kickstart validation

To check for potential errors in kickstarts, prior to installation, use cobbler validateks. This function will check all profile and system kickstarts for detectable errors. Since pykickstart is not future-Anaconda-version aware, there may be some false positives. It should be noted that cobbler validateks runs on the rendered kickstart output, not kickstart templates themselves.

6.14. Network Topics

6.14.1. PXE Menus

Cobbler will automatically generate PXE menus for all profiles it has defined. Running cobbler sync is required to generate and update these menus.

To access the menus, type menu at the boot: prompt while a system is PXE booting. If nothing is typed, the network boot will default to a local boot. If “menu” is typed, the user can then choose and provision any Cobbler profile the system knows about.

If the association between a system (MAC address) and a profile is already known, it may be more useful to just use system add commands and declare that relationship in Cobbler; however many use cases will prefer having a PXE system, especially when provisioning is done at the same time as installing new physical machines.

If this behavior is not desired, run cobbler system add --name=default --profile=plugh to default all PXE booting machines to get a new copy of the profile plugh. To go back to the menu system, run cobbler system remove --name=default and then cobbler sync to regenerate the menus.

When using PXE menu deployment exclusively, it is not necessary to make Cobbler system records, although the two can easily be mixed.

Additionally, note that all files generated for the PXE menu configurations are templatable, so if you wish to change the color scheme or equivalent, see the files in /etc/cobbler.

6.14.2. Default PXE Boot behavior

What happens when PXE booting a system when Cobbler has no record of the system being booted?

By default, Cobbler will configure PXE to boot to the contents of /etc/cobbler/default.pxe, which (if unmodified) will just fall through to the local boot process. Administrators can modify this file if they like to change that behavior.

An easy way to specify a default Cobbler profile to PXE boot is to create a system named default. This will cause /etc/cobbler/default.pxe to be ignored. To restore the previous behavior do a cobbler system remove on the default system.

cobbler system add --name=default --profile=boot_this
cobbler system remove --name=default

As mentioned in earlier sections, it is also possible to control the default behavior for a specific network:

cobbler system add --name=network1 --ip-address= --profile=boot_this

6.14.3. PXE boot loop prevention

If you have your machines set to PXE first in the boot order (ahead of hard drives), change the pxe_just_once flag in /etc/cobbler/settings.yaml to 1. This will set the machines to not PXE on successive boots once they complete one install. To re-enable PXE for a specific system, run the following command:

cobbler system edit --name=name --netboot-enabled=1

6.14.4. Automatic installation tracking

Cobbler knows how to keep track of the status of automatic installation of machines.

cobbler status

Using the status command will show when Cobbler thinks a machine started automatic installation and when it finished, provided the proper snippets are found in the automatic installation template. This is a good way to track machines that may have gone interactive (or stalled/crashed) during automatic installation.

6.15. Boot CD

Cobbler can build all of it’s profiles into a bootable CD image using the cobbler buildiso command. This allows for PXE-menu like bring up of bare metal in environments where PXE is not possible. Another more advanced method is described in the Koan manpage, though this method is easier and sufficient for most applications.

6.15.1. DHCP Management

Cobbler can optionally help you manage DHCP server. This feature is off by default.

Choose either management = isc_and_bind in /etc/cobbler/dhcp.template or management = "dnsmasq" in /etc/cobbler/modules.conf. Then set manage_dhcp=1 in /etc/cobbler/settings.yaml.

This allows DHCP to be managed via “cobbler system add” commands, when you specify the mac address and IP address for systems you add into Cobbler.

Depending on your choice, Cobbler will use /etc/cobbler/dhcpd.template or /etc/cobbler/dnsmasq.template as a starting point. This file must be user edited for the user’s particular networking environment. Read the file and understand how the particular app (ISC dhcpd or dnsmasq) work before proceeding.

If you already have DHCP configuration data that you would like to preserve (say DHCP was manually configured earlier), insert the relevant portions of it into the template file, as running cobbler sync will overwrite your previous configuration.

By default, the DHCP configuration file will be updated each time cobbler sync is run, and not until then, so it is important to remember to use cobbler sync when using this feature.

If omapi_enabled is set to 1 in /etc/cobbler/settings.yaml, the need to sync when adding new system records can be eliminated. However, the OMAPI feature is experimental and is not recommended for most users.

6.15.2. DNS configuration management

Cobbler can optionally manage DNS configuration using BIND and dnsmasq.

Choose either management = isc_and_bind or management = dnsmasq in /etc/cobbler/modules.conf and then enable manage_dns in /etc/cobbler/settings.yaml.

This feature is off by default. If using BIND, you must define the zones to be managed with the options manage_forward_zones and manage_reverse_zones. (See the Wiki for more information on this).

If using BIND, Cobbler will use /etc/cobbler/named.template and /etc/cobbler/zone.template as a starting point for the named.conf and individual zone files, respectively. You may drop zone-specific template files in /etc/cobbler/zone_templates/name-of-zone which will override the default. These files must be user edited for the user’s particular networking environment. Read the file and understand how BIND works before proceeding.

If using dnsmasq, the template is /etc/cobbler/dnsmasq.template. Read this file and understand how dnsmasq works before proceeding.

All managed files (whether zone files and named.conf for BIND, or dnsmasq.conf for dnsmasq) will be updated each time cobbler sync is run, and not until then, so it is important to remember to use cobbler sync when using this feature.

6.16. Containerization

We have a test-image which you can find in the Cobbler repository and an old image made by the community: https://github.com/osism/docker-cobbler