Simple declarative package management

For Arch Linux

List the packages you want installed in /etc/decpac.conf. Run decpac and packages will be installed/uninstalled until the set of installed packages matches the list. This doesn't manage config files, cache files, other generated files, etc. If you like this but want more rigorous declarative package management check out Nix and NixOS.

I've been using it for a couple months now (April 2018).

Why declarative management?

1. You want to install the same packages on a different system. Just copy decpac.conf over and run decpac!
2. You're looking for a program that does X, and there are 10 programs that say they do X. If you install them all, you'll definitely forget to uninstall them. Install them using pacman directly and decpac will uninstall them the next time you run it.
3. You're trying to clean up your system but you don't remember why you installed a package, or even what it does. Organize and annotate your decpac.conf with comments!
4. Help me out here.
5. Diff your package list!

Usage

Install with

pip install decpac

If you don't have a configuration file, create one with

sudo decpac generate

Edit your /etc/decpac.conf (be careful not to delete system files) (see Config file syntax below).

Then run

decpac

to synchronize your packages.

Config file syntax

The config file looks like:

{
        install_main: [
                sudo,
                pacman,
                --noconfirm,
                -S,
        ],
        install_aur: [
                trizen,
                --noconfirm,
                -S,
        ],
        installed: [
                nvidia,
                lib32-nvidia-utils,
                trizen,
		...

                * audio *
                alsa-utils,
                (aur) alsaequal,
                alsaequal-mgr,
                alsaplayer,
		...
	],
},

This is a luxem file, which is like JSON but quotes are optional for single words and you can add comments like * this is a comment *.

(aur) specifies an AUR package. It's installed with whatever helper you specified in install_aur (trizen worked for me).

Implementation notes

Most AUR helpers had issues, such as installing all deps from AUR or not flagging dependencies as dependencies (or rather, flagging them all as explicit). I worked around that somewhat but it would be nice to implement AUR functionality directly. It may make things more efficient too.

Customizing AUR builds makes things nonreproducible so I avoid doing that. Specifying customizations in decpac.conf might be a good feature.

It would be awesome if decpac could install Ruby/Node packages as well using npm2arch and its ilk.

Renamed packages need to be renamed in the config manually. decpac could update the config file automatically but de/reserializing deletes comments. Maybe making a (comment) type would work?

Related projects

• Nix - A strict declarative package (and config) manager that can be used on Arch, and also the basis of Linux distro NixOS
• aconfmgr - A declarative Arch-native package and config manager