Extending the p2 Repository Format in Fedora
We ship a lot of OSGi bundles in Fedora.
$ repoquery --repofrompath=foo,http://kojipkgs.fedoraproject.org/repos/f21-build/latest/x86_64/ --repoid=foo -q --whatprovides "osgi(*)" | wc -l 693
We already allow packagers to have requirements based on the OSGi metadata to some extent. We’re supporting Require-Bundle in specfiles through use of the “osgi(…)” provide but even with this, building Eclipse plugins has always seemed like a giant hack, and even more so when compared to the latest Java Maven Packaging Examples. Building with Tycho requires that your OSGi dependencies be in a p2 repository (update site). We obviously can’t just point to the eclipse.org update sites for our Fedora builds since all of our dependencies must be from packages within the Fedora infrastructure that were built from sources. Initially the simplest way to achieve this was to look on the system for all OSGi bundles, publish them to a p2 repository, and then feed this directly into Tycho’s build target platform.
This approach certainly works (and that’s what the copy-platform-all script did) but it still requires performing the same steps every time one needs to feed OSGi bundles to Tycho or some other application that uses p2 repositories. The end-goal is to have tighter integration with tools like XMvn, and to make packaging an easier task. To do this we really need to have our system locations be recognized as p2 repositories so that we could also take advantage of p2 APIs.
When I got back from EclipseCon NA 2014, I started playing around with this idea of having filesystem directories being recognized as a p2 repository.
$ eclipse -application org.eclipse.equinox.p2.director -repository fedora:/usr/share/java/ -installIU org.swtchart
with the result being that ‘org.swtchart’ from somewhere in ‘/usr/share/java’ gets installed into the eclipse instance. This was easy to implement and fairly simple to integrate with Tycho so that we only inject a few system locations and get proper dependency resolution.
I’ve named this fedoraproject-p2 mainly because Fedora’s requirements are the driving force but I could see this being useful in many other cases.
This has been used for some time now on rawhide, and with the addition of things like the xmvn-p2-installer-plugin, it won’t be long until Eclipse plugin packaging will be drastically simpler.