smart-live-rebuild (C) 2010 Michał Górny <email@example.com> Released under the terms of the 3-clause BSD license or the GPL-2 license.
smart-live-rebuild is a Python script to aggregate live packages from users' system, update them and merge the updated ones.
What's the point in creating such tool when portage-2.2 comes with builtin @live-rebuild support?
The @live-rebuild set of portage and similar tools simply do the task of aggre- gating the live packages and calling emerge to update them. This is acceptable if you don't have many live packages and don't call it frequently.
But if you used a whole bunch of live packages (like live X11, for example), you'd probably get a little irritated having to rebuild all of them, even if most of them weren't even touched by upstream.
Of course, there's LIVE_FAIL_blah_blah in git.eclass. It works indeed but have you used it with, say, more than 90 packages? You can imagine how long it takes for portage to reload itself 90 times after dying on each non-modified repo.
And that's where smart-live-rebuild comes in handy. It updates all the live packages on its own, and supplies portage with ready-made list of packages which indeed have changed and need to be rebuilt.
- parallel updates support
As you might have already noticed, fetching from remote repositories suffers from a constant start-lag, wasting a lot of time without really consuming network bandwidth.
To overcome that, smart-live-rebuild support running multiple updates in para- llel. Although it might seem insane at first, assuming that most repositories aren't really changed or have quite a small set of changes, using it could save a lot of time.
To use parallel updates, pass the '-j N' ('--jobs N') parameter to s-l-r, where N stands for the number of updates running in parallel.
- quickpkg backup support
If you used a large set of live packages for some time, then you probably met an issue where the new upstream version was broken, and you had to make an effort in order to find a working commit to revert to.
This is where the '-Q' ('--quickpkg') option becomes useful. It makes s-l-r call 'quickpkg' to create the binary packages for the current versions of packages queued to be updated.
Although it wastes some time in each update, it allows you to easily and quickly revert to the previous working version of the package -- without unnecessarily recompiling it. Moreover, the binary packages contain a copy of environment.bz2, allowing you to get the 'last surely working commit'.
- real update checking
s-l-r doesn't assume it is the only application which can update the repository. Whenever possible, it tries to retrieve the currently-installed commit (revi- sion) from vardb instead of relying on the repository state before update.
This way, the rebuild list will contain all packages which are outdated in the system and not only those which it has updated in the particular run. This means you no longer have to worry about having to manually update packages whenever you abort the merge or update process.
In most cases, s-l-r needs to be run as root. This has serious security impli- cations, which the scripts tries to overcome dropping the privileges whenever possible.
In fact, the superuser privileges are only required to call emerge and quickpkg (the latter might in some cases work as regular user but that has further implications). It is also required to update the repositories unless userpriv is enabled (otherwise, portage privileges are enough).
s-l-r loses its privileges as soon as configuration and command-line options are parsed (this is required in order to support disabling the privilege dropping), and performs the repository updates as the 'portage' user (as long as userpriv is enabled).
If 'quickpkg' is scheduled and/or '--pretend' is not being used, s-l-r forks to drop the privileges and performs the updates using forked subprocess. Otherwise, it directly drops the privileges in the parent process.
Moreover, in the latter case s-l-r can be run directly by the 'portage' user.
PORTAGE SET SUPPORT
Apart from being called directly, smart-live-rebuild provides a package set for portage-2.2, called SmartLiveRebuild.sets.SmartLiveRebuildSet. Please take a look at 'sets.conf.example' file for a use example.
Various options to smart-live-rebuild may be set in a configuration file too. The path to that file can be specified as '--config-file' (or '-c'), and the default one is '/etc/portage/smart-live-rebuild.conf'.
The configuration file has a format similar to Windows .ini files. Sections correspond to available profiles, with '[smart-live-rebuild]' being the default one (other can be specified using '--profile'/'-p'). The keys for respective options match the command-line argument names, with 'no-' prefix stripped and all dashes ('-') replaced with underscores ('_').
The values for boolean types can be specified in any way suitable for ConfigParser python class (i.e. true/false/yes/no/on/off). The 'type' list has to be comma-separated.
Example config file may look like:
[smart-live-rebuild] jobs=3 erraneous_merge=no type=git,subversion
Additionally, configuration files can be chained. To do so, just specify path to the next configuration file as 'config_file'. Please notice though that currently they aren't read in reverse order, so further configuration files will replace values set by yours.