m4cfg

A gross very good and useful Makefile-and-m4-based system for consistently generating configuration files across many hosts.

Wow, Sounds Great! Where do I sign up?

Check out the git repo, ya dingus

$ git clone https://notabug.org/al/m4cfg

And if you want to see it in action (or want to perv on my private configuration), check out the mein-doots branch:

$ git checkout -b mein-doots

What the fuck is this steaming pile of shit and How do I use it?

The basic principle behind this system is that you'll create a configuration package for each program/system you use. Each package has a name and an output file. When you run the root Makefile, the output file will be generated. Usually included in a configuration package is an install.sh script. It (usually) does exactly what you'd expect - in fact since you're the one who's gunna be writing it, hopefully you know exactly what it does...

Creating a Configuration Package

Each configuration package has a name and an output file. So to generate a new configuration package, all that's needed is to pass these parameters to the root Makefile, using the addcfg target:

$ make NAME='packagename' OUTPUT='package.cfg' addcfg
mkdir: created directory 'packagename/'

Success!

Now if you cd into the new package directory, you'll find a few things:

packagename/
├── base.m4
├── hosts.txt
└── Makefile

Usually you won't need to do anything to hosts.txt or Makefile, unless you're looking at doing something strange and unconventional. However, base.m4 is where you place the configuration data which is common to all hosts. Since its processed as an M4 file, you can do all sorts of wacky shit with it. Like including host-specific configuration from another m4 file...

packagename/base.m4

include(HOST`.m4')

Where HOST is a predefined macro containing the hostname of the current system (or the HOST variable passed to the root Makefile. More on this later...). So if you're on a system named kevin, this line will look for an m4 macro file called kevin.m4 in the package directory at compile-time.

After placing some configuration data in base.m4, we return to the root and compile the configuration:

$ make

Note that this will actually compile all of the available configuration packages, but for our purposes this is fine for now. This command will cook you a big steaming pile of packagename, and then you'll find a package.cfg file sitting in the packagename/kevin/ directory. What you do with it from there is totally up to you. Personally, I add an install.sh to each package directory and run it manually to install the output file to its relevant location. Something along the lines of this:

packagename/install.sh

#!/bin/sh
TARGET="$HOME/.config/package"
[ -z "$HOST" ] && HOST=$(hostname)
[ ! -d "$TARGET" ] && mkdir -pv "$TARGET"
ln -srvf "$HOST/package.cfg" "$TARGET/"

It's probably a good idea to use symbolic links so you don't have to reinstall the configuration files every time you change them.

Build Options

Currently, there's a couple of variables that you can pass to the root Makefile to alter its behaviour:

Variable	Behaviour
HOST	Overrides the target host. Defaults to the hostname of the current system
NAME	Set the target configuration package
OUTPUT	Set the name of the output file for a particular package

Building for Many Hosts

The root Makefile has an allhosts target. It does exactly what you think, assuming you are a rational person. Note that before using this target, you need to add the target hostnames to each configuration package. This can be done using

$ make NAME='target-package' addme

or by manually adding hostnames to the target-package/hosts.txt file. Using the make method, the HOST variable can also be altered to add foreign hosts.

Running make allhosts will then cook up many steaming piles of configuration.

Removing Configuration Packages

This is done using the rmcfg target. You'll also need to pass it a package name:

$ make NAME='target-package' rmcfg

Only do this if you're absolutely sure. There are no sanity checks!

It is important that you use this method instead of manually running rm -rf on the package directory; m4cfg also needs to update some internal files.

Alternatively, if you're in the mood for danger, you can run make purge to irrevocably remove every single configuration package

Creating Package Archives

You can generate package archives in the superior tar.xz format using the archive target on the root Makefile. If you pass in the NAME variable, it will generate a tarball containing just the contents of that particular package. Otherwise, an archive with the contents of the entire configuration tree will be generated.

Help! There are duplicates in export.txt / hosts.txt!

make clean # <- Don't worry. Is safe.