Get the specificed version of Ruby onto a Linux host by any means necessary, and cache it in S3.

install_ruby.sh

#!/bin/bash
# Get the specificed version of Ruby onto a Linux host by any means necessary. Invoke like this:
# 
#    curl https://raw.github.com/gist/2785410/install_ruby.sh | bash -s -- -r '1.9.3-p125' -b mybucket
#
# Jacob Elder <jacob@boundless.com>

usage() {
  echo "Usage: $(basename $0) -r 1.9.3-p125 -b mybucket"
  exit 1
}

pull_or_clone() {
  if [ -d $2 ] ; then
    ( cd $2 ; git pull | grep -v 'Already up-to-date.' || true )
  else
    git clone $1 $2
  fi
}

# The exit code for `s3cmd ls` is not meaningful.
s3_file_exists() {
  s3cmd ls $1 | grep -q $1
}

setup() {
  tempdir=$(mktemp -d /tmp/install_ruby.XXXXXXXX)
  trap "rm -rf $tempdir" INT EXIT
  cd $HOME

  # We're going to either download it from S3, or build it locally and save it
  # to S3. For this, we'll need a filename describing this environment.
  os=$(uname -s)
  machine=$(uname -m)
  case $os in
    "Darwin")
      echo "This doesn't really support Darwin just yet."
      #exit 1
      release=$(sw_vers -productVersion)
      ;;
    "Linux") 
      . /etc/lsb-release
      os=${DISTRIB_ID}
      release=${DISTRIB_RELEASE}
      ;;
    *)
      echo "Don't know what to do with $os."
      exit 1
      ;;
  esac
  archive="ruby-${ruby_version}_${os}_${release}_${machine}.tar.bz2"
  s3_path="s3://${bucket}/Ruby/${archive}"

  # Check that s3cmd works
  s3cmd ls s3://${bucket} 2>&1 > /dev/null
  if [[ $? -ne 0 ]] ; then
    echo "s3cmd isn't installed or configured!"
    exit 1
  fi
}

save_state() {
  echo "Caching this Ruby environment at $s3_path"
  tar --create --bzip2 --directory $HOME --file $tempdir/$archive .rbenv
  s3cmd put $tempdir/$archive $s3_path
}

while getopts "hr:b:s" OPTION ; do
  case $OPTION in
    h)
      usage
      ;;
    r)
      ruby_version=$OPTARG
      ;;
    b)
      bucket=$OPTARG
      ;;
    s)
      save_only=1
      ;;
  esac
done

if [ -z $ruby_version ] || [ -z $bucket ] ; then
  usage
fi

setup

if [ ! -z $save_only ] ; then
  save_state
  exit
fi

pull_or_clone git://github.com/sstephenson/rbenv.git ~/.rbenv
pull_or_clone git://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build
export PATH=$HOME/.rbenv/bin:$PATH

eval "$(~/.rbenv/bin/rbenv init -)"

if [ ! -d ".rbenv/versions/${ruby_version}" ] ; then
  
  if s3_file_exists $s3_path ; then

    # It exists, use it.

    s3cmd get $s3_path $tempdir
    echo "Extracting archived Ruby environment"
    tar --extract --bzip2 --directory $HOME --file $tempdir/$archive 

  else

    echo "gem: --no-ri --no-rdoc" > .gemrc

    rbenv install $ruby_version
    rbenv rehash
    rbenv global $ruby_version

    rbenv exec gem install bundler
    rbenv rehash

    save_state

  fi

fi  

rm -f ~/rbenv.sh
echo 'export PATH=$HOME/.rbenv/bin:$PATH' >> ~/rbenv.sh
echo 'eval "$(rbenv init -)"' >> ~/rbenv.sh