Ease installation of software outside the Ubuntu repositories

[pablomme]

Binary package hint: software-center

Steps to reproduce (true story):
- Your friend whom you've just introduced to Ubuntu tells you that she's downloaded the just-released Firefox 4 and wants help installing it on her maverick laptop
- Seeing the .tar.bz2 file, start explaining the basics of software management
- Explain that the preferred method of installing a program is to use the Ubuntu repositories via the software centre, and that software versions are intended to remain fixed during each Ubuntu cycle
- Explain that, nonetheless, in the event of really wanting to install a piece of software or a specific version which is not available in the Ubuntu repositories, there are other methods; in decreasing order of preference: PPAs/APT repos (packages self update), stand-alone debs (packages register with the package manager, hence can be removed easily), and lastly stand-alone tarballs like the one she got from mozilla.org
- Successfully demonstrate/outline installation and uninstallation from the Ubuntu repositories, from a stand-alone deb, and from a tarball
- After what so far seemed to go down surprisingly well, try to explain that in order to add a PPA (the second-best method) you need to google for (essentially) "site:launchpad.net ppa <software>", go to the result, copy some string by hand, open the software centre, open Edit > Software Sources, go to the Other Software tab, click a button, paste the string and press OK. APT repositories are no better than this
- Exemplify by adding a PPA containing gimp 2.7
- Fail to use software centre to upgrade gimp
- Dismiss failure and update gimp using update-manager
- Now try to explain that in order to remove the PPA you just added and restore the 2.6 version of gimp you need to install some package called 'ppa-purge', go to the command line ("the what what?") and type some gibberish
- Silently agree with your friend's conclusion that in order to install software in Ubuntu you need to be a computer geek

Launchpad PPAs offer a lot of additional software these days. However they are not intuitive to use, and the wealth they offer remain the privilege of a lucky few. Same goes for conventional APT repositories like medibuntu. And tarballs are, whether we like it or not, often used to distribute packages in a (sub-optimal) distribution-agnostic manner - games and browsers come to mind. All four installation mechanisms should be handled properly.

Two PPA-related features *must* be added:
- One-click addition of PPAs and other APT repositories, e.g., via some new URI scheme like 'apt-add://<repository>' or similar, in line with the existent 'apt://<package>'. Integration in apt.ubuntu.com would be a bonus, of course (e.g. "apt.ubuntu.com/ppa/ubuntu-wine"). Launchpad's PPAs should prominently display a button/link to add the PPA, and software-centre should handle it gracefully. Embedding the repository signing keys in the URLs would be ideal (e.g. "apt-add://<repository>?key=ABC123")
- Integration of ppa-purge into software-centre, so that one can right-click on a PPA or APT repository on the left pane, select 'remove' and have all relevant packages correctly removed/downgraded.

Additionally, it would be useful if we had:
- Ability to search Launchpad's PPAs from software-centre directly.

And a last, somewhat crazier idea to deal with tarballed software:
- When opening a tarball that may contain software, the user should be given an option to extract to some pre-defined directory under $HOME (e.g., $HOME/.user-software, or perhaps $HOME/User\ Software or something), and possibly register any .desktop files it finds within the tarball with Gnome. The best (least-intrusive) option in my mind is to integrate this into the file-roller interface in the form of a button saying "This is software and I would like to install it", and probably launch an extenal application to handle it. [As a side effect, we get a button that could be used, in the case of .exe files (handled by file-roller by default), to trigger the installation of wine.] And of course, large warning signs pointing out the many problems of this type of installations [or of trying to run windows software on Ubuntu] should be displayed, with links to search the repositories or launchpad for the package in question [or a native version/replacement for the windows program].

There are many potential drawbacks to installing software other than from the official repositories, but the Ubuntu repositories can't possibly cover everything (especially so for newer package versions - by policy), and we need to help users accomplish the task by streamlining and unifying the installation process as much as possible.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: software-center 3.1.24.1
ProcVersionSignature: Ubuntu 2.6.38-7.38-generic 2.6.38
Uname: Linux 2.6.38-7-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Thu Mar 24 03:28:01 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110301.1)
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: software-center
UpgradeStatus: Upgraded to natty on 2011-03-23 (0 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.