Marc Dougherty

⚒ ⚙ ⛵

Building Debian packages for my own use.

17 July 2018

I’ve been a debian/ubuntu user for years, but had always been intimidated by the packaging process (because i tried to read the New Maintainer’s Guide). I decided to give it a shot recently, because I was building experimental software for the raspberry pi, and grew tired for scp and rsync.

Note: The advice below does not abide by the debian packaging policy.

Vincent Bernat’s Pragmatic Debian Packaging is a great place to get started. Unfortunately, I only found it near the end of my efforts.

So… why?

I had been tinkering with several different raspberry-pi-based projects, and I found copying around whole directories from my computer (where I do most of the coding) to the pi was becoming tedious. I was also looking for a clean and simple way to cleanly remove a project if I later decided it was no longer needed.

I had looked into a few other ‘installation methods’, like shell scripts, and tarballs, etc. But none of them seemed to be quite simple enough to set up.

“Simple?” you say, “you picked debian packages because you wanted simple?!”

Well, no. It was not simple, but it does teach me more about debian packages, which is sure to be beneficial down the line.

Before we start

There is a great deal of tooling built around debian packaging, but if we start with the robots, there will be cleanup work to do later.

  1. set the environment variables DEBEMAIL to your email address, and DEBFULLNAME to your full (first + last) name. These are used in the autogenerated steps to come, and its easier to set them now than to fix the generated output.
  2. (Optional) put the following in ~/.devscripts, which is read by many debian tools:

    # Do not require directories to conform to packagename-version standard.
    DEVSCRIPTS_CHECK_DIRNAME_LEVEL=0
    # dont rename the directory when the version number changes.
    DEBCHANGE_PRESERVE=no
    # Dont sign packages. I just build them for me, so signing is pointless.
    DEBUILD_DPKG_BUILDPACKAGE_OPTS="-uc -us"
    

Generate boilerplate: dh_make

I started by creating a basic debian package with dh_make --native. This gives me a “native” debian package, meaning that there is no separate source tarball to worry about. For my use case, i felt this was best, as it avoids the intermediate step of tarring up my files. This approach can be found in an appendix of the debian maintainer docs

dh_make --native --packagename=$pkgname_$version

Where $pkgname is the name of the package you’re building, and $version is some arbitrary version number.

See docs on source/format for more information about native vs non-native packages.

This command will generate a debian/ directory, with lots of files in it. Anything that ends in .ex is an example, and can safely be deleted if you wish.

Customize the boilerplate for your needs

The most important two files generated are debian/control and debian/rules.

debian/control

The control file is metadata about your package. there are several placeholders in there, like Description and Section which should be filled in.

Build-Deps is a bit harder, and should include packages needed to build the package. Depends should list packages required for your package to function. I often guess at the right packages, and test by running a package build.

debian/rules

This is actually a Makefile, with rules for building your package. Thanks to debhelper (dh and friends), this file is typically short in my experience. There’s a variety of helper utils for specific purposes (for example, dh-golang helps build packages written in Go, and is discussed below).

Trials and Errors: debuild

debuild is the main tool for building packages. now that we’ve customized some of the debian build files, its time to give it a shot. It probably wont work, but it will tell us what needs to be fixed. The lintian tool makes helpful suggestions that are probably worth fixing, and points out placeholders that need to be filled in.

The build process assumes that there’s a toplevel Makefile, though if you are packaging a simple collection of files, this is not necessary. See the section below on Install and Configuration.

Eventually, you should end up with a functional debian package in the parent directory of your package. If that’s all you needed, you’re done!

Helpers, and other considerations

Install and Conffile

For packages that do not require compilation, or are platform-agnostic (e.g. python scripts), a Makefile feels a bit overwhelming. There’s a simpler approach: debian/install. this file describes how files from the package build directory should be installed by the package.

For example, a directory with files a, b, and c might choose to install into different directories like this:

a /usr/bin/
b /usr/sbin/
c /etc/

That file c looks like a configuration file, and we dont want to overwrite with the package version when we upgrade. debian/conffiles provides a mechanism for this. Just include the path to the installed configuration file (i.e. etc/c) in here, and dpkg will treat it as a configuration file.

Helper: dh-golang

The debian go team has a golang packaging guide for full details, but here’s the short version:

  • install dh-golang, which is a deb helper for making go packages.
  • in debian/rules set DH_GOPKG to the name of your go package (what you’d usually go get)
  • in debian/rules, add the following options to the dh invocation: --buildsystem=golang --with=golang
  • run debuild again, and hopefully get a go package!

For binary-only packages, set DH_GOLANG_BUILDPKG in rules, pointing to only the packages that are binaries (which are all under cmd, right?)

Helper: dh-systemd

If you are creating services to run at startup, say on a raspberry pi, you’ll likely want to include some systemd configuration. There are some docs for dh-systemd.

For debhelper versions >= 10, systemd is activated by default, according to the above.

add a systemd file as debian/packagename.systemd, and it will be included in the deb package.