Build Debian packages and offer them in PPAs

Lap of Honor

The KUP example build demonstrates how to deal with major changes before you can build a new package successfully: Persson ported Kup 0.6 to KDE 5; version 0.5.1 still used the old KDE 4.

Therefore, you have to define various KDE 5 libraries as dependencies so that your packages build properly in Launchpad later. Kup tells you what these dependencies are if you trigger the build process with:

$ dpkg-buildpackage -rfakeroot -uc -us

Of course, this is guaranteed to fail because the chroot environment does not have the required KDE 5 libraries. However, you can read the missing libraries from the error message and find out in which Ubuntu package the corresponding library is hiding using the Search function in the package directory [6].

You will want to add the additional build dependencies to the line beginning with Build-Depends in the debian/control file (Figure 2). Do not forget to insert a comma before you enter the additional dependencies (Listing 2).

Listing 2

KDE 5 Dependencies


Figure 2: The debian/control file contains, among other things, information about additional packages needed for the build. Otherwise, the corresponding run in the Launchpad automatic build will fail.

Executing dpkg-buildpackage the first time created a set of current 0.6.0-1 sources, so you are better off starting over completely if you want to trigger the package build again. To start over, the command:

rm -rf kup-0.6.0
dpkg-source -x kup_0.6.0-1.dsc

creates a clean, new kup-0.6.0-1 directory.

One last Kup peculiarity needs to be handled: The path to plugins for the KDE control center has changed between KDE 4 and KDE 5, so you need to add two lines to the end of debian/rules (Figure 3; Listing 3) and use dch -i to create a new entry in debian/changelog (Figure 4).

Listing 3

New Rules for debian/rules


Figure 3: The revised debian/rules file for Kup 0.6.
Figure 4: The revised debian/changelog file.

The debian directory is now fit for Kup 0.6.0-1. Create a clean 0.6.0-2 source package with the following:

dpkg-buildpackage -rfakeroot -S -sa

for upload onto Launchpad.


If you want to share the fruits of your labors with others, the Ubuntu Launchpad platform is just the right tool. You'll need to register first, then start configuring the account once you find the confirmation email in your Inbox: Enter the ID for your GPG key in Launchpad to upload packages into your own PPAs.

Launchpad uses GPG as a control mechanism: The .dsc file that belongs to each Debian source package must be signed with the same GPG key that belongs to your account (Figure 5). If you have not dealt with GnuPG before or do not have your own keys, now is a good time to change that [7] – you won't get far in matters regarding a PPA in Launchpad without GPG keys.

Figure 5: Before you can upload to Launchpad, you need to set your own GPG key.

To land directly in the GnuPG configuration of your Launchpad account, use the address<LaunchpadID>/+editpgpkeys. Enter your key ID here and permanently link the key in Launchpad with your profile.

Signing the Source Package

The penultimate step before finishing is to sign the source code package produced by dpkg-buildpackage. For security reasons, you want to exit the chroot environment. The debsign tool is needed next, so install the package on your local system with:

# apt-get --no-install-recommends \
  install devscripts

From the command line, go to the folder where the source package is located and sign it by entering:

debsign kup_0.6.0-2.dsc

If required, the tool will prompt you to enter your GPG password and then create the signatures.

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