The Power(ful Tooling) of Gentoo

People often ask me for my reasons to use Gentoo. Many perceive it as a "hard" distro that takes a lot of time. While it does come with a learning curve, I don't perceive it as particularly "hard", as the documentation is very thorough and the community is very helpful. And the tooling you get to maintain your system is far beyond what I've come across with any other GNU+Linux distribution.

This blog post will highlight some of the key features I love about Gentoo. There are certainly many more perks that I don't (yet) use, so please feel free to inform me of other cool things that I missed.

Configurability

One of the main reasons for preferring Gentoo is due to the ease of configuring it to work just the way you want.

A great example for this would be with init choices. Many distributions only support systemd these days. As I'm not a big fan of this particular system, I want to change this. But even asking a question about this will get you a lot of hatred in most distribution communities. In Gentoo, however, changing init is supported and well documented, allowing you to pick from a range of possible inits.

USE flags

One of the core concepts of Gentoo are the USE flags. These allow you to easily alter the software you're compiling to use the features you want. They can also be used to indicate which library you would like to use to make use of a certain feature, if there are multiple implementations available.

make.conf

Like most distros that work with self-compiled packages, Gentoo has a make.conf file available to specify some default arguments in to use while compiling. Unlike most other distros, Gentoo's make.conf also allows for some configuration of the emerge utility.

For instance, I use my make.conf to ensure emerge always asks for confirmation before performing actions. I also ensure that the build system, portage, is heavily sandboxed when building packages.

Additionally, like all configuration files in /etc/portage, it can be made into a directory. In this case, all files in the directory will be loaded in alphabetical order. This allows for easier management using tools like Ansible.

Ease of patching

Another feature I find very useful of Gentoo, is the ease of applying my own patches to software. If you have a custom patch for a package that you want to be applied, all you have to do is drop it in a directory in /etc/portage/patches. The directory is should be in is the same as the package's name the patch is intended for. For instance, I have the following patch in /etc/portage/patches/www-client/firefox:

diff --git a/browser/extensions/moz.build b/browser/extensions/moz.build
index 6357998..c5272a2 100644
--- a/browser/extensions/moz.build
+++ b/browser/extensions/moz.build
@@ -5,15 +5,10 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 DIRS += [
-    'activity-stream',
     'aushelper',
     'followonsearch',
     'formautofill',
     'jaws-esr',
-    'onboarding',
-    'pdfjs',
-    'pocket',
-    'screenshots',
     'webcompat',
 ]

Whenever a new Firefox is released and built, this patch will be applied on it to remove some of the features I dislike.

Ebuilds and overlays

In Gentoo vocabulary, ebuild files are the files that describe how a package is to be built, which USE flags it supports and everything else relating to a package. An overlay is a repository of ebuild files. Everyone can make their own, and easily add 5 lines in their repos.conf to use it. In most cases, they're just git repositories.

The documentation on everything around ebuilds is superb, in my experience, especially compared to other distros. It is incredibly easy to get started with, since it's made to be usable with very little effort. While being simple, it's also very flexible: All default behaviours can be overwritten if needed to get a package to build.

Binary packages

Yes, you read that right. Binary packages! Contrary to popular belief, Gentoo does support this. You can instruct emerge to build binary packages of all the packages it compiles, which can then be re-used on other systems. It does need to be compiled in such a way that the other machine can use it, of course. You can't simply exchange the packages of an x64 machine with and ARM machine, for instance. You can set up a cross build environment to get that particular usecase going, though.

If you want to easily share the binary packages you build with one machine, you can set up a binhost, and have emerge pull the binary packages on the other systems as needed using --usepkg. There actually is a binhost provided by Gentoo itself, but it seems to only contain important packages used to restore systems into a working state.

Tooling

Some of the core tooling available to any Gentoo user has already been talked about. But there's some additional tooling you can install to make your life even better.

genkernel

One of the hardest tasks to newcomers to Gentoo is often to compile a kernel. Of course, Gentoo has an answer for this, genkernel. The defaults genkernel will give you are reasonably sane if you just want to have a kernel that works. Of course, you can still edit the kernelconfig before compilation starts. It will also build an initramfs when requested, that goes along with the kernel. When things have been made, the kernel and initramfs will be moved to /boot, and a copy of the working kernelconfig is saved to /etc/kernels. All you need to remember is to update your preferred bootloader's configuration to include your new kernel.

eix

eix is a utility most Gentoo users use to update the Portage repositories and search for available packages. The interface is considered more convenient, and it's a bit faster at getting your results.

To get a quick overview of which packages are in need of updates, you can run eix -uc (updates, compact). To sync the Portage tree and all overlays, eix-sync is the way to go. This will ensure the cache used by eix also gets updated.

In addition to having a cleaner interface and being faster, it also comes with additional tools for keeping your system sane. The most notable to me is eix-test-obsolete.

This utility will report any installed packages that are no longer provided by any repository (orphaned packages). It will also report all configuration lines that affect such packages. This is really valuable in keeping your configuration maintainable.

glsa-check

The glsa-check utility is part of the app-portage/gentoolkit package. When ran, it will produce a list of all packages which have known vulnerabilities. It will use the GLSA database for the list of known vulnerabilities. This can be much easier than subscribing to a mailing list and having to check every mail to see if a vulnerability affects you.

qlop

qlop is another utility that comes with app-portage/gentoolkit. This program parses the logs from emerge to give provide you with some information. I use this mostly to see compile times of certain packages using qlop -Htvg <package-name>. Using this, I can more easily deduce if I want my desktop (with a stronger CPU) to compile a certain package, or if it'll be faster to just compile it on my laptop.