I'm sure many openSUSE users have already heard about the goodness of the openSUSE Build Service (OBS). But how many have already tried to use it as developer? I didn't -- until recently. A couple weeks ago I had found a wrong dependency in the calibre package, and today I was in the need for a newer version of hplip. I found that using OBS is much easier than I expected. Don't believe me? Have a look how easy it can be to update a package. It all follows the popular github fork-and-pull-request development style. As an example I'll use (a subset of) the changes I did today to the hplip package.
Step 0: Prepare your system to use OBS
Instead of duplicating existing documentation, just have a look at the OBS tutorial at the openSUSE wiki. You'll only need to follow Step One. Basically, this means installing the required packages for OBS and creating a working directory.
If you're done, switch to your working directory and you can follow the next steps*.
Step 1: Branch (fork) the original package you want to modify
$> osc branch Printing hplip
Step 2: Do a checkout of the branched project
$> osc co home:YOUR_USERNAME:branches:Printing/hplip
$> cd home:YOUR_USERNAME:branches:Printing/hplip
Step 3: Do the required changes to the package (the actual work!)
$> wget http://prdownloads.sourceforge.net/project/hplip/hplip/3.12.6/hplip-3.12.6.tar.gz
$> # verify binary (gpg, md5sum, etc.)
$> osc add hplip-3.12.6.tar.gz
$> osc del hplip-3.12.4.tar.gz
# adjust the spec file as necessary ...
Step 4: Build locally to verify your changes
$> osc build openSUSE_12.1
Instead of openSUSE12.1 you can use any target your might want to test (e.g. openSUSE_Factory etc.). This command is actually pure magic, it pulls all dependencies, installs them into a chroot build environment, and builds the package. Awesome!
You can now even install the resulting RPM package, the above command will tell you where to find it at the end of its output (probably somewhere in /var/tmp/build-root/home/abuild/rpmbuild/RPMS). You actually should do that and verify that everything works as expected.
Step 5: Finish it up
If you're happy with your changes, and everything works as it should, we can get ready for submission.
First, add a changelog entry:
$> osc vc
will open an editor and allow you to add a changelog entry into the already prepared text template.
Now, check that you added/deleted all files by calling
$> osc status
If everything looks good, commit the package to OBS by using
$> osc commit
You can now go to the OBS web interface and watch your package build, or use
$> osc results
to see the results of the build process on the openSUSE servers. Note that building may take some time, depending on the OBS load and obviously your package.
Step 6: Submit the changes to the maintainer
Everything is great? The last step
$> osc sr
sends a "pull request" (in git language) to the package maintainer. You can see the status of this request in the web interface as well.
Now you only need to wait for the maintainer to accept your changes and then: Congratulations, you've made your possibly first contribution to openSUSE!
* Actually, the steps as written here will not result in a working package. The update of hplip required some other changes that I didn't document here, but I hope the real-life examples will help to make the steps more understandable.