What is packaging and why should you care?

Or: Only heathens install tarballs

Todd Zullinger <tmz+cplug@pobox.com>

Anal retentive package monkey (and small-time Fedora packager)

Package management series goals

• Provide an understanding of what packages are and why they should be used
• Explain how to take advantage of various package management tools
• Teach how to create new packages or update existing packages in various formats
• Present information needed to make an informed choice on which packaging system best fits a particular environment
• Persuade you to never allow a tarball to be installed on any of your systems

Briefly, what is a package?

• Collection of files, metadata, and helper scripts to install and configure software on your system
• Instructions for extracting source code from a tarball (or other archive), building it into a binary, and installing it
• Database of package information that can be queried

From tarball to binary

• configure && make && make install
• This is WRONG!
• Very, very WRONG!!
• You are a bad admin if you do this
• You might as well kill kittens

Think of the kittens

• No (sane) way to reliably remove software
• No (sane) way to verify files installed have not been modified
• No (sane) way to handle dependencies
• No (sane) way to record build options or what patches were applied
• No (sane) way to prevent file conflicts
• Numerous methods and tools used
• Build tools must be installed

Packages to the rescue!

• Accountability
• Reproducibility
• Dependency tracking
• Easy install
• Clean removal
• Sysadmin sanity
• Profit!

Accountability

• Is foo installed? What version?
• What files does foo install?
• Where did /usr/bin/foo come from?
• Is foo a legitimate package from my distro?
• What have I installed recently?

Reproducibility

• Build once, install on multiple systems
• Documented build process, compile options, patches, etc.
• Eliminate spurious differences between systems
• Ensure systems have the same packages and versions installed

Dependency tracking

• Package foo may require libcrack
• Ensure libcrack is installed when foo is installed
• Update foo when libcrack is updated (if necessary)
• Remove foo when libcrack is removed
• Some systems even know if libcrack was installed as a dependency of foo and can remove libcrack when foo is removed
• Track packages needed in order to build

Easy install

• Ensure any user or group accounts it needs are created
• Modify config files
• Update desktop menus, icons, font caches, etc.
• Configure, enable, and/or start services
• Execute system commands and/or run scripts

Clean removal

• Delete all files that were installed
• Remove any users or groups that were created
• Undo config file changes
• Stop running services provided by the package
• Execute system commands and/or run scripts

Common package formats

• deb — used on Debian, Knoppix, Ubuntu and others
• rpm — used on CentOS, Fedora, Mandriva, Red Hat, SUSE and others
• tgz — used on Slackware
• ebuild — used on Gentoo

Coming soon to CPLUG

If you liked this talk, you might also enjoy:

• Getting to know your package manager
  • debs
  • rpms
  • ebuilds
• Packaging roundup (aka, My package manager can beat up your package manager)

http://pobox.com/~tmz/cplug/packaging-intro/