The Version Controlled Operating System

I hate having to remember which packages on each new operating system install. I keep a small script called josh-env.sh in a private Github repository (remember, Github now has unlimited private repositories!) that I then make sure is present in my home directory. The script does two things: it contributes important environment variables (typically the environment variables I use to run builds, as I might on the CI server) that are themselves version controlled, and it records the contents of my Homebrew and Homebrew Cask installations into text files and then git commit and git push those files if the contents have changed.

#!/bin/bash

c=`pwd`
d=`dirname $0`

## contribute environment variables
source $d/josh-env-vars.sh


## record homebrew

mkdir -p $HOME/bin
export PATH=$PATH:$HOME/bin
# lets make sure that this and the brew manifest of the OS itself are all version controlled


BC=$d/brew-cask.txt
B=$d/brew.txt

brew cask list > $BC
brew list > $B

cd $d

n=`date`
git add $B
git add $BC
git commit -a -m "updated brew manifest $n."

last_commit_status=$?

if [ $last_commit_status -eq 0 ]; then
  echo "changes detected on $n. running git push."
  git push;
fi

cd $c

Naturally, this script needs to be run at somepoint. It's a cheap operation so I run it on every new user shell, inside $HOME/.zshrc:

...
source $HOME/josh-env/josh-env.sh
...

This way, if for any reason I need to restore a system tomorrow, I can git clone the private project on a new machine and restore everything. It might be as simple as:

#!/bin/bash

cat brew.txt | while read l ; do brew install $l ; done

cat brew-cask.txt | while read l ; do brew cask install $l ; done

I keep everything heavy weight inside of Dropbox, so that restores naturally. I keep all code inside Github, and those restore naturally. This ensures that the remaining personalizations to my environment are recorded and restored as well.