Section 8.6. Find the Right Update Repository


8.6. Find the Right Update Repository

Default configurations can be annoying when you're trying to keep your system up-to-date. If you're located outside the U.S., default update repositories for U.S.-based distributions can doom you to long wait times, and sometimes even failures, when you try to update your systems to the latest features and security updates.

Some distributions such as Debian suggest that it is inappropriate to connect directly to Debian servers for all but security updates. It increases the costs for this distribution of volunteers and makes access more difficult for those who mirror the Debian repositories.

In general, repositories are organized into separate installation and update repositories. The installation repository includes all packages associated with the original release of a distribution; for example, the installation repositories for Fedora Linux include the packages that you would find on the Fedora Linux CDs. The corresponding update repository includes any packages built after the initial distribution release. One exception is Red Hat Enterprise Linux (RHEL), where update packages are incorporated into the main repository (which is known as a channel on the Red Hat Network).

In this annoyance, we'll examine default update servers, and how you can reconfigure your systems to point to mirrors more well suited to your system. As this book is limited to Red Hat/Fedora, SUSE, and Debian, I do not address mirrors available for other distributions. However, the techniques are similar.

In some cases, the best update channel is one that you configure yourself. In "Too Many Computers to Update over the Internet" in Chapter 11, I'll show you how to configure a mirror of your preferred update server. A local mirror can minimize update-related traffic on your Internet connection and often speeds updates if you have more than a few Linux computers on your network.

Be careful about repositories from different sources. For example, if you configure repositories from Fedora and from third parties on the same system, you may end up with incompatible packages and unresolvable dependencies.


8.6.1. Debian

Debian Linux uses the apt commands to keep its systems up-to-date. The apt commands rely on sources configured in the /etc/apt/sources.list configuration file. Before you modify this file, you need to know how the directives that you can add to this file work. I've summarized some of the more important directives in Table 8-2. As you can install the apt commands on many RPM-based systems, I've included some directives you might see on RPM-based distributions.

Table 8-2. /etc/apt/sources.list directives

Directive

Description

deb

Uses the deb command to install packages

rpm

Uses the rpm command to install packages; assumes that apt packages are installed on an rpm-based system

deb-src

Applies to Debian-style source packages

rpm-src

Applies to RPM-style source packages

file:///

Connects to locally mounted directories

oldstable

Specifies the former stable distribution, which is Debian Woody as of this writing

stable

Specifies the current stable distribution, which is Debian Sarge as of this writing

testing

Specifies the current beta distribution, which is Debian Etch as of this writing

unstable

Specifies the current developmental distribution, which is Debian Sid as of this writing

main

Notes the primary Debian repository, which includes most freely licensed packages

contrib

Notes the Debian repository of free packages on which non-free packages depend

non-free

Notes the Debian repository with non-open source licenses


Now you'll want to configure your /etc/apt/sources.list file to point to repositories closer to your network. Unless the mirror is slow, pick the mirror physically closest to you. The official list of Debian mirrors is available from http://www.debian.org/mirror/list.

For example, if I were closest to Berkeley, CA, I'd connect to the mirror at the University of California at Berkeley. As you can see, FTP and HTTP mirrors are available. If you have a special architecture, make sure it's listed in the righthand column. I prefer FTP servers for my system; I can link to the noted server at ftp://linux.csua.berkeley.edu/debian/.

In my /etc/apt/sources.list file, I start with the deb directive, proceed with the URL of the repository, and add the label for the distribution, as well as the repositories to which I want access. As I use Debian Sarge, that is the stable distribution. As I want access to all three repositories, I end up with the following line in my configuration file:

 deb ftp://linux.csua.berkeley.edu/debian/ stable main contrib non-free 

If I want access to the source code for each of these repositories, I can add the following line:

 deb-src ftp://linux.csua.berkeley.edu/debian/ testing main contrib non-free 

Unfortunately, Debian does not support mirrors of its security updates; you'll need to keep the following entry in your /etc/apt/sources.list file:

 deb http://security.debian.org/ testing/updates main contrib non-free 

Courtesy of the developers behind Conectiva Linux (now a part of Mandriva), you can install and use the apt commands on a number of RPM-based distributions. In fact, there are apt-based repositories available for Fedora Core and SUSE Linux.


8.6.2. SUSE

While some have created apt repositories for SUSE Linux, the company encourages the use of official repositories and mirrors through YaST Online Update (YOU). While SUSE encourages the use of its GUI interface, you can also configure YaST updates from the command line. As the root user, run the yast online_update command to open the update menu shown in Figure 8-1.

Figure 8-1. YaST Online Update


Naturally, you'll want to configure updates from the mirror closest to you. The Installation Source drop-down text box includes several preconfigured locations. It also allows you to select a User-Defined Location, which you can select from one of the SUSE mirrors.

If you're running SUSE Linux Professional, you can select your mirror from the official list at http://www.novell.com/products/suselinux/downloads/ftp/int_mirrors.html. To configure your own location, take the following steps:

  1. Select the mirror you prefer from the list described above. Make a note of the URL.

  2. Press Alt-I, and select User-Defined Location.

  3. Tab to and select New Server. When this opens the "Select Type of URL" window, select the type of server. If it's remote, it's an FTP or HTTP server. Make the selection and click OK.

  4. When the "Server and Directory" window opens, make sure the right protocol (FTP or HTTP) is marked, and then enter the URL for the server in the Server Name text box.

  5. Enter the directory with the SUSE repository in the "Directory on Server" text box.

  6. For most SUSE Linux Professional mirrors, the default anonymous authentication is sufficient. If you're configuring an update for SUSE Linux Enterprise Server, you'll need your Novell account information. Select OK.

  7. Now you should be ready for your update.

While the list of official mirrors seems limited, you may want to search further. I've found SUSE repositories on servers listed in the Fedora mirror list. For example, I've been able to configure updates from the servers at the University of Mississippi. The URL for its server is ftp://mirror.phy.olemiss.edu, and the associated "Directory on Server" is suse/suse/.

In "Too Many Computers to Update over the Internet" in Chapter 11, I show you how to configure a local mirror. Once you share that mirror on your network, you can reconfigure YaST Online Update to point to that share.

You can configure apt for SUSE Linux. All you need are packages from ftp://ftp.gwdg.de/pub/linux/suse/apt/SuSE/version-i386/RPMS.suser-rbos/, where version corresponds to the distribution version for SUSE Linux Professional. Several apt-based repositories are listed at http://linux01.gwdg.de/apt4rpm/.


8.6.3. Fedora

For much of this book, Red Hat Enterprise Linux (RHEL) and Fedora are essentially the same distribution. Both distributions use the same basic Red Hat tools. However, unlike RHEL, Fedora updates are freely available. Fedora's default version of /etc/yum.conf points to files in the /etc/yum.repos.d directory for updates.

Older versions of Fedora did not include an /etc/yum.repos.d directory; all repositories were listed in /etc/yum.conf.


By default, Fedora Core includes six files in that directory, described in Table 8-3, which you can use to link to the repositories.

Table 8-3. Fedora repository files in /etc/yum.repos.d

File

Description

fedora.repo

Connects to the repository with the original installation packages

fedora-updates.repo

Links to the repository with update packages

fedora-updates-testing.repo

Connects to proposed updates; don't use unless you're willing to risk installing beta software

fedora-devel.repo

Connects to developmental packages, which may change daily; formerly known as Rawhide

fedora-extras.repo

Connects to the Extras repository with packages beyond the standard installation

fedora-extras-devel.repo

Connects to proposed updates to the Extras repository; don't use unless you're willing to risk installing beta software


By default, there are no active directives in the devel and testing files. Unless you're willing to take the risks associated with software that is not ready for production, you should not activate directives in those files. In fact, you can delete fedora-updates-testing.repo, fedora-extras-devel.repo, and fedora-devel.repo without problemsand probably should on systems for regular users.

However, you will want to change the defaults in the first two files. The default version of fedora.repo includes:

 [base] name=Fedora Core $releasever - $basearch - Base #baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/$releasever/$basearch/os/ mirrorlist=http://fedora.redhat.com/download/mirrors/fedora-core-$releasever enabled=1 gpgcheck=1 

By default, $releasever is the released version number as defined in /etc/redhat-release and $basearch comes from the uname -i command, which specifies the hardware platform. If you want to disable a repository, set enabled=0.

As you can see, the repository depends on the mirrorlist directive, which points to a URL with a list of specified repositories. For Fedora Core 4, the default mirrorlist file is fedora-core-4, which includes a list of mirrors on several different continents. When yum looks for an update repository, it takes a random URL from this file, which is less than ideal.

Therefore, you'll either want to specify a repository closer to you or at least revise the mirrorlist file to one that makes more sense. There is a directory of mirrorlist files available at http://fedora.redhat.com/download/mirrors/ with lists for a number of different countries. I use the fedora-core-3.us.west file, which includes a number of mirrors suitable for me.

Alternatives for Updating Packages

If you prefer the Red Hat Update Agent, also known as up2date, on Fedora Linux, apply the settings described in this annoyance to the /etc/sysconfig/rhn/sources configuration file.

As of Fedora Core 5, the Update Agent is not part of the default Fedora installation (but is still available for Fedora Core, and remains the default for Red Hat Enterprise Linux). Future Fedora Core releases will use tools such as the Package Updater, also known as Pup. As it serves as a frontend to yum, see the next annoyance, "Avoid Dependency Hell with yum" for more information.

If you prefer apt for Fedora Core, there are apt-related packages you can install from a third-party repository such as atrpms.net (apt and synaptic). These packages are preconfigured to help you select an appropriate mirror; just run the apt-get mirror-select command.


8.6.4. Red Hat Enterprise Linux

Updates for Red Hat Enterprise Linux (RHEL) are supported through the Red Hat Network. They are organized differently from most other Linux distributions, in that there is no separate update repository. When an update is released, you can install it from the same channel as the main installation repository. (RHEL repositories are known as channels.)

Each system requires a subscription, which provides access to several update channels. As shown in Figure 8-2, I can assign a number of different channels to one of my systems that is subscribed to RHEL 4.

Figure 8-2. Red Hat Network channels


The channels shown in the figure are just those to which I subscribe. If you have a Red Hat Network subscription, you can click Channels on the top bar to review a full list of available channels. I describe some of the Red Hat Network channels in Table 8-4. For more information, navigate to https://www.redhat.com/software/rhn/ or contact Red Hat sales at 866-273-3428.

Table 8-4. Red Hat Network channels

Channel

Description

Main

The channel associated with a distribution; includes the original binary packages

Beta

Packages planned for RHEL updates

Extras

Packages not available under open source licenses

Hardware certification

Packages to test hardware compatibility with RHEL

Software development kit

Red Hat's application build environment

Network tools

Network and kickstart configuration tools


If you want to verify the channels to which you've subscribed, run the following command:

 # up2date --show-channel rhel-i386-as-4 rhel-i386-as-4-extras rhel-i386-as-4-hwcert rhel-i386-as-4-sdk rhn-tools-rhel-4-as-i386 

As you can see from the output, this particular system is subscribed to five different channels, all of them based on RHEL 4. In order of display, they correspond to the following channels: main, extras, hardware certification, software development kit, and network tools.

If you want to cache content locally, you can set the Red Hat Update Agent to save downloaded RPMs in the /var/spool/up2date directory. You can then use the yum tools described in the next annoyance to create headers from this repository. Downloaded RPMs are, by default, deleted after installation.

To make the Red Hat Update Agent save the RPMs after installation, take the following steps:

  1. Run the up2date-nox --config command.

  2. Select the number associated with the keepAfterInstall option (it varies).

  3. When you're prompted for a New Value for keepAfterInstall, type Yes.

  4. Press Return twice to save your new settings.

You can also use the Red Hat GUI tool to configure updates. Start with the up2date-config command to open the Red Hat Network Configuration window. Under the Retrieval Installation tab, check the "After installation, keep binary packages on disk" option.


The Red Hat Network also offers specially configured Proxy and Satellite Servers, which can cache update content locally. For more information, read the associated manuals at http://www.redhat.com/docs/manuals/RHNetwork/.



Linux Annoyances for Geeks
Linux Annoyances for Geeks: Getting the Most Flexible System in the World Just the Way You Want It
ISBN: 0596008015
EAN: 2147483647
Year: 2004
Pages: 144
Authors: Michael Jang

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