Package Management and Mirroring

About

This is a walkthrough of how to set up cobbler to be a full fledged mirror of everything install and update related that you might ever be interested in.

Updates and package installation are closely related. If you're doing one, it makes sense to do the other.

Why would you be interested in this?

Suppose you manage a large number of machines and are (A) not allowed to get to the outside world, (B) bandwidth constrained, or (C) wanting to get access to 3rd party packages including custom yum repositories.

All of these are good reasons to want a mirror server for all things kickstart and yum related. Cobbler can do that for you.

How To

The following instructions walk through an example of setting up a mirror of a Fedora install tree, including any updates. This will require a good bit of hard disk space (we'll show you how to hardlink to save space later), so be prepared :). These same commands work for all varieties of RHEL, Fedora, or Centos.

First, follow the setup for a DVD import here using the Fedora 12 install media. See Using Cobbler Import.

Once the import is complete, we'll add the mirrors...

$ cobbler repo add --mirror=http://download.fedora.redhat.com/pub/fedora/linux/updates/12/ --name=f12-i386-updates
$ cobbler repo add --mirror=http://download.fedora.redhat.com/pub/fedora/linux/releases/12/Everything/i386/ --name=f12-i386-everything

Please replace i386 with your preferred architecture. If you own x86_64 or ppc machines as well, just change it. If you're not running Fedora, insert your yum URLs of choice. It all works the same!

These are just a few common examples. Say you have a RHEL5 or Centos4 machine? Perhaps you would want to add something from EPEL, RPM Fusion, or someplace else? No problem.

Now that we've added the mirrors, let's pull down the content. This will take a little while, but subsequent updates won't take nearly as long.

    cobbler reposync 

Now, that the repositories are mirrored locally, let's create a cobbler profile that will be able to automatically install from the above repositories and also configure clients to use the new mirror.

    cobbler profile add --name=f12-i386-test --repos="f12-i386-updates f12-i386-everything" --distro=F12-i386 --kickstart=/etc/cobbler/sample_end.ks 

Now, any machines installed from this mirror won't have to hit the outside world for any content they may need during install or with yum. They'll ask for content from the cobbler server instead. Cool.

RHN

This is rather experimental, but if you have a provisioning need for fast local installs without hitting an outside server repeatedly (say you have a slow pipe), you can try:

    cobbler repo add --name=insertnamehere --mirror=rhn://rhn-channel-name 

That's just the channel-name, no server. This only works on RHEL5+ and you'll need entitlements for the channel in question. You also want a version of yum-utils at least equal to 1.0.4.

Post Install Yum Usage

If you want your installed systems to be automatically configured to use your install server for updates, go into /etc/cobbler/settings and set the following:

yum_post_install_mirror: 1

(Don't do this if the servers can't reach the cobbler server at the value set up in settings or if you're going to move the installed machine to a different network later)

Updates And Cron

As you're mirroring repositories that change (and probably even include some security updates from time to time), putting "cobbler reposync" on crontab would be a good idea. Cobbler reposync will update the content in all of your repositories.

You can disable updating of certain repos that you've already pulled down and don't wish to contact again by toggling the --keep-updated flag on the repo. Make sure you reposync them at least once.

Use of the following flags will ensure smoother updates from cron:

cobbler reposync --tries=3 --no-fail

This will allow Cobbler to keep trucking if one of your mirrors has problems.

Also Apt

Starting, we can also do apt mirroring (see Distribution Support ).

cobbler repo add --name=foo --mirror=http://url --breed=apt --arch=i386

This is useful with Debian distributions (those that have --breed=debian in the distro object), see [Distribution Support](Distribution Support]

Saving Space

To eliminate space duplicated between mirrored updates and install trees, run the following command

cobbler hardlink

This requires that you have first installed the package 'hardlink'.

To Review

The above steps have set up your cobbler server as a full fledged mirror, not just for install trees (which are imported using "cobbler import" not reposync -- read Using cobbler import), but also for future package installs and updates with yum.

Installation content during anaconda and afterwards will be pulled from your cobbler mirror, not the outside world. You should see faster installs and won't have to worry about whether your client machines have outside internet connectivity.

Cobbler handles all of the yum, reposync, and createrepo magic for you, so you don't have to know how they work. Plus, the kickstarts are automatically aware of the configuration and build themselves out based on what repos are defined. Bottom line: you don't need to know how any of this stuff works. Cool.

If you have questions or want to clear up something in this document, ask on the mailing list or stop by #cobbler on irc.freenode.net.


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