Package Management: Building Things
It's been almost three weeks since the previous blog post and some people start wondering what the current status is and what were working on exactly, so it's time for an update. Incidentally the time is perfect for an update anyway, since we've just reached our first important milestone: haikuporter supports hierarchical building of packages.
Given a package name, it can now analyze the HaikuPorts tree containing all the build recipes, recursively determine which other packages are required for building the package and build everything that's needed in the correct order. Each package is built in a clean chroot, meaning an environment in which only the packages are installed that have explicitly been declared a build requirement for the package in question in its build recipe. This way we make it significantly less likely that the package we build doesn't declare a requirement to another package that it actually has, which would potentially break things when installing it later.
I already wrote in the previous blog entry how we planned to reach the current goal. With a few exceptions we followed that plan. haikuporter is still written in Python, though, since unlike we feared there weren't a lot of problems with Python in the chroot environments. So far we don't have any translation tool from Gentoo-Portage EBuild files to our build recipes. In the long run it might be a good idea, but the number of packages we're currently interested in (i.e. the one needed for a regular Haiku release build) isn't that great (less than 50), so it isn't worth the work ATM.
While Oliver has done all the work on haikuporter and the required build recipe changes, I worked, as planned, on libsolv -- it has been updated to the current state of development and its Haiku port has been brought to a working state -- implemented dependency solving support in the package kit -- a few things are still missing but it is not far from completion now -- and added a "resolve-dependencies" command in our "pkgman" tool. This command is used by haikuporter to resolve the dependencies between the packages that can be built and to determine what exactly needs to be installed in the chroot for building a certain package.
Save for fixing a few packagefs and bindfs bugs that was all I needed to contribute to the current milestone, so I was free to work on a few other things as well. Most importantly I started working on the package daemon, a component of our system design that was entirely missing yet. Essentially it provides the central service for managing the actually activated packages. It monitors the packages directories of all installation locations and activates packages dropped there by the user and deactivates packages the user removes. That functionality was previously implemented in packagefs. The package daemon will, however, also check whether all requirements of new packages are fullfilled and, if necessary alert the user when there are conflicts or additional packages (e.g. required libraries) have to be installed. This part hasn't been implemented yet, though when started the daemon does already verify whether the currently activated package sets are consistent.
The package daemon will also perform the activation and deactivation of packages as requested by the package manager ("pkgman" and later also the GUI application) via package kit classes. That's something I've already started working on. I've also started with an "install" command in "pkgman". Given a set of package names to install, it already resolves the dependencies from the configured repositories. Missing yet is the actual downloading of the packages and telling the package daemon to activate them. Once "install" is done, "remove" and "update" shouldn't be that much work anymore, since although outcome is different, the steps to perform are very similar (resolve dependencies, download new packages (if any), tell the daemon what to de-/activate). Once those are done the basic "run-time" package management functionality would be usable, i.e. one could manage software repositories and install, remove, and update packages.
There's plenty of other work left to do, though. Our next milestone is updating the package management branch to the current state of Haiku development. ATM our branch is still based off a two years old Haiku. Since a lot of ported software has been updated in the meantime, we first need to build packages for those new versions, which in turn require us to create working build recipes for them. That's something Oliver is going to work on next.
Our main focus for the remainder of our contracts is to get package management to a point where we can merge the branch back into the main development line. We definitely won't be able to complete every aspect of package management in the remaining time, but getting the basic functionality on top of solid foundations done and having it in the main repository will hopefully encourage other developers to help out filling the gaps.
So what's the foundation work we'd like to get done?
On the package building side there are some more features needed in haikuporter, like building multiple packages from a single recipe (e.g. a base, a development, a debug info, ... package) and building complete repositories.
The whole repository infrastructure area needs some serious thoughts (we've only done some brainstorming so far) plus tool support.
The gcc2/gcc4 hybrid support needs to be added back to the build system. It has to work differently from how it worked before, so it had been removed two years ago to not get in the way. There are also a few other build system issues that need to be addressed (like mimesetting files before packaging them).
We have several changes to the package format on our TODO list. It might be a good idea to address those before "going live". On the other hand that could be done later (bump the format version, keep support for the old version around for a while), although that adds some work overhead at that time.
Finally, an update to the link list from my previous post: We have cleaned up and consolidated our GitHub repositories. Now, owned by the "Haiku" organization, there are a HaikuPM and a BuildtoolsPM repository in which both Oliver and I are working.
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