Another free RPM management utility is available that provides many of the features of both vendor solutions such as up2date or urpmi and of third-party utilities such as autoUpdate or KPackage. This tool is apt-rpm, a port of the Debian Project’s excellent apt (Advanced Package Tool) software.
The Debian Project (www.debian.org/) is a nonprofit volunteer group that develops a Linux distribution, Debian GNU/Linux. The group uses a different package format, dpkg, which was developed independently of and simultaneous to Red Hat’s creation of RPM. The two formats, dpkg and RPM, are very similar in terms of utility and functionality. In addition to having created a package format, the Debian Project later developed a collection of software, apt, which could be used to manage and install dpkg-format software. And, since Debian distributions are typically installed over the Internet, this apt software has to supply advanced distributed package management functionality.
In many respects, Debian’s implementation of apt is very similar to the functionality provided by Red Hat’s up2date/Red Hat Network products or Mandrake’s urpmi software. On Debian systems, apt is a client tool used to select and install new software packages or to update existing packages already installed on the system. To do this, it accesses a user-configured list of resources that supply new packages; these resources are typically the Debian Project’s FTP or Web servers, though they can also be CD-ROMs or local or remote file systems. For apt to be able to download packages from a resource such as a CD-ROM or an FTP server, that resource must supply two things: the software packages being downloaded and a database supplying metadata about all the packages in the repository. These resource databases are essential for apt to operate. For this reason, apt can only be used to update systems from apt-capable repositories.
Although apt was created by the Debian Project and designed for dpkg-format software packages, nothing about apt requires that it inherently be usable only with dpkg-format packages. Because of this, and because of its powerful capabilities, Conectiva, a Brazilian Linux distribution vendor (www.conectiva.com), extended apt to support management of RPM packages in addition to dpkg packages. Conectiva’s work, commonly referred to as apt-rpm, makes the apt client software available for use on any RPM-based Linux distribution. Conectiva also provides its customers with access to apt-capable FTP servers. A related project, apt4rpm (http://apt4rpm.sourceforge.net/), supplies the necessary utilities that can be used to make any RPM repository apt-capable. By creating apt-capable servers using apt4rpm and then installing apt-rpm on the client systems, any RPM-based distribution, such as Red Hat Linux, Mandrake Linux, Caldera/SCO OpenLinux, or SUSE Linux, can then be easily managed using apt.
Note
The freshrpms.net site, mentioned previously, provides a touted apt repository.
Administrators managing multiple dispersed machines as well as those used to Debian administration often find it useful to configure their machines to use apt; its dependency tracking is far better than any other tool, except for Red Hat’s up2date/RHN combination. To use apt, administrators must install it on their machines and have access to an apt-capable RPM repository for the distribution they use. Several public FTP sites that support apt are now available for most of the major RPM-based distributions. Also, the administrator can create another apt-capable repository.
Configuration of machines to use apt is simple. The apt and libapt RPMs simply need to be installed. Although binaries are sometimes available, the best success can usually be obtained by building binary RPMs from the latest Conectiva apt SRPM (source RPM), available at ftp://ftp.conectiva.com/pub/conectiva/EXPERIMENTAL/apt/.
Once apt and libapt RPMs are installed, the sources.list file in /etc/apt needs to be modified to reference the apt-capable software site that will be used. For example, to configure a machine to access the apt-capable Red Hat Linux 7.2 software distributed by the Tuxfamily.org server, the /etc/apt/sources.list file needs to list:
rpm http://apt-rpm.tuxfamily.org/apt redhat-7.2-i386/redhat os
rpm http://apt-rpm.tuxfamily.org/apt redhat-updates-7.2/redhat os
These two lines, respectively, access the Red Hat Linux 7.2 and Red Hat Linux 7.2 errata RPMs being served by the system apt-rpm.tuxfamily.org. If you also want access to source RPMs, the following lines are necessary as well.
rpm-src http://apt-rpm.tuxfamily.org/apt redhat-7.2-i386/redhat os
rpm-src http://apt-rpm.tuxfamily.org/apt redhat-updates-7.2/redhat os
In addition to, or instead of, using public apt-capable servers, many sites want to create their own apt servers. If apt is being used to manage all the machines in the enterprise, a custom apt server might be needed that contains apt-accessible RPMs of all the custom software used in the enterprise. This can be done using the tools provided by the apt4rpm package (http://apt4rpm.sourceforge.net).
Once apt has been installed on clients, and the clients have been configured to access an apt-capable server, keeping systems updated is simple. The command apt-get update updates the client system’s apt database of available software, after which the command apt-get upgrade upgrades all currently installed software to the latest version available in the software repository. By listing a site that provides vendor errata updates in /etc/apt/sources.list and then setting up a nightly cron job to run the apt-get upgrade command, administrators can be sure that client systems always have the latest errata installed. You can use a similar technique to ensure that all client systems are always up to date with the latest custom in-house applications. To do this, set up your own apt server and ensure that the latest custom applications are placed on the apt server.
In addition, apt simplifies interactive installation of RPMs on systems that are using it. The command apt-get install package retrieves the named RPM from the apt-capable software repository and installs it. If the package requires any dependencies that are not already resolved, apt will ask for confirmation, then download and install the package and all dependencies. Similarly, apt-get remove package uninstalls the named RPM. If any other packages depend on it, it will prompt for confirmation, then uninstall the named RPM and all of its dependencies.
In addition to these command-line utilities, several graphical front-end tools for manipulating apt are currently being ported for use with apt-rpm. Because of its ease of use for automating installation of system errata and necessary custom software, and because of the excellent dependency tracking it provides for interactive installation and uninstallation of software, apt-rpm can be excellent for managing RPM-based systems.
