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Package Managers

Package Managers. What are they and why we use them. Thoughts of an admin. Installing software is painful Installing a lot of software is extremely painful Installing a lot of software on a lot of machines is HELL. 舉例 - LOL. 天賦、符文 道具. Before Packages. Install from source

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Package Managers

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  1. Package Managers What are they and why we use them

  2. Thoughts of an admin • Installing software is painful • Installing a lot of software is extremely painful • Installing a lot of software on a lot of machines is HELL

  3. 舉例 - LOL • 天賦、符文 • 道具

  4. Before Packages • Install from source • Time consuming • Varying configuration

  5. Improvement 1 • Copy the binaries • Setup scripts? • Version? • Dependencies?

  6. Package - Basic • Archive • Binaries • Supporting files • Setup script

  7. Package – Improvement • Versioning • 1.0.x • 1.1.x • … • Upgrades!

  8. Package - Dependencies • Program A requires library B to work • If library C is available, program A will work better/faster!

  9. Example – Call of Duty • Requires: DirectX • Works better with: PhysX

  10. Package ManagersLow Level • Unpacking packages • Run configuration scripts • Dependency checks • …

  11. Package ManagersHigh Level • Fetch from remote repositories • Search • Install additional packages to meet dependencies • Handle complex upgrades

  12. Package Repository • Collection of packages • Maintained by distribution • Multiple versions • Index

  13. Package Managers

  14. Focus on Debian DPKG & APT

  15. Types of Packages • Binary Package • Meta Package • Virtual Package

  16. Binary Package • Normal package • Source is available • Architecture • Dependent • Compiled binary files • Independent • Scripts • Documents • Data files

  17. Meta Package • Depends on other packages only • Rename • git-core -> git • Default version • gcc -> gcc-4.6 • Python -> python2.7 • Can be creative!

  18. Virtual Package • Does not really exist • Names common functionality • Other binary packages “provide” a virtual package • c-compiler is provided by • gcc • gcc-4.6 • clang

  19. Commonly Used Commands • apt-get • apt-cache • aptitude • Frontend to the first 2 commands

  20. Search for a package • apt-cache search ^vim$ Search pattern State flags

  21. Search Patterns • Patterns are regular expressions • Aptitude supports complex patterns • See reference • Search requires guessing • Just like Googling

  22. Differences • Aptitude and apt-cache have slighty different behavior • Aptitude looks at package name only • Apt-cache looks at description as well

  23. State Flags

  24. Try it! • You want to install a web server. What do you look for? • What should you actually install?

  25. Looking at a package • Web interface • http://packages.debian.org • CLI • apt-cache show XXX • aptitude show XXX • Debian Control File • Try it now!

  26. Package Info • Name • State • Version • Priority • Section • Maintainer • Architecture • Dependencies • Description

  27. Package Info - State • installed • not installed • removed • …

  28. Package Info - Version • Vim: 2:7.3.547-6 • 2: -> Epoch • 7.3.547 -> Upstream version • -6 -> Debian package revision

  29. Package Info - Priority • Required • Important • Standard • Optional • Extra

  30. Package Info - Dependencies • Depends • Recommends • Suggests • Conflicts • Replaces • Breaks • Provides • Syntax: http://www.debian.org/doc/debian-policy/ch-relationships.html

  31. Installing / Removing • apt-get install XXX • aptitude install XXX • remove/purge • hold/unhold • upgrade • dist-upgrade

  32. remove vs. purge • Remove keeps config files in system • Purge = Remove + delete config files

  33. hold/unhold • Keep a package at a specific state/version unless explicitly request otherwise

  34. upgrade vs. dist-upgrade • upgrade only updates currently installed packages • dist-upgrade will do anything to satisfy all new dependencies

  35. Try it now! • Install a web server • Then remove it • See that config files are still there • Then purge it

  36. Making a Package

  37. Why? • Customize • Software not packaged yet • Become a maintainer? • Build your own

  38. Making your first package • Basic structure • package/XXX • Files you want to package • package/DEBIAN/control • Debian control file • package/DEBIAN/xxx • Package scripts, other control files • dpkg-deb –b package

  39. Homework – Build a meta package • Name: nasa-hw • Should always install • gcc no older than 4.7 • make newer than 3.80 • Should not install when • clang is installed • Maintainer: Your ID <your email> • Use your judgment for other fields • Read the documents! • Submit .deb file

  40. Too simple? • Debianrelated source code • source/debian/rules • source/debian/control • source/debian/changelog • source/debian/…

  41. Guidelines for packaging • Debian新維護人員手冊 • http://www.debian.org/doc/manuals/maint-guide/ • Get other package sources and see how other people do it • apt-get source XXX

  42. Packages for packaging • build-essential • dpkg-dev • debhelper • CDBS • dh_make • lintian

  43. build-essential • Meta package that depends on essential tools for packaging • You need to install additional tools/libraries • debhelper, cdbs, … • lib*-dev

  44. dpkg-dev • Basic tools for package development • dpkg-buildpackage

  45. Debhelper • Collection of commands to assist packaging • Wraps complex steps • Splitting files between different packages • Generating shared library dependencies • Generate and sign binary packages • …

  46. CDBS • Common Debian Build System • Class based system • Supports different build systems • make, ant, cmake, … • http://www.slideshare.net/petereisentraut/the-common-debian-build-system-cdbs

  47. dh_make • Prepare source code for packaging • Always uses debhelper • Supports CDBS

  48. lintian • Check packages for errors

  49. Steps to packaging • http://www.debian.org/doc/manuals/maint-guide/first.en.html • Get source code • Unpack • dh_make • Install build dependencies • Check control file • Check installation paths • Build package • dpkg-buildpackage -b

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