Installing rbenv through shell script - ruby

Question

I've created a shell script to install rbenv onto a fresh virtual machine, everyone seems to be working fine, however, once and a while it seems that rbenv fails to install. I'd like to add some extra error checking throughout the way to ensure that the install happens, and if something failed, re-start the install.
Some notes:
This is a small part of a larger script
This is all done through whiptail dialog
I'm redirecting the output to an events.log file >&$log_fd...
This is what I currently have:
set_rbenv(){
# install rbenv
RUBY_VERSION="2.1.4"
RBENV_ROOT="/root/.rbenv"
PROFILE="/root/.bashrc"
# check if rbenv is installed
if [[ ! `which rbenv` ]]; then
if [[ ! -d "$RBENV_ROOT" ]]; then
echo "Cloning rbenv..." >&$log_fd 2>&1
git clone https://github.com/rbenv/rbenv.git $RBENV_ROOT >&$log_fd 2>&1
fi
if [[ ! -d "$RBENV_ROOT/plugins/ruby-build" ]]; then
git clone https://github.com/rbenv/ruby-build.git $RBENV_ROOT/plugins/ruby-build >&$log_fd 2>&1
fi
if [[ ! `grep -e '/.rbenv\/bin' $PROFILE` ]]; then
echo "rbenv not in PATH ... adding..." >&$log_fd 2>&1
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> $PROFILE 2>&1
fi
if [[ ! `grep -e '^\eval "$(rbenv init -)"' $PROFILE` ]]; then
echo "rbenv init not in .bashrc... adding..." >&$log_fd 2>&1
echo 'eval "$(rbenv init -)"' >> $PROFILE 2>&1
fi
. $PROFILE
echo "Finished Installing rbenv..." >&$log_fd 2>&1
else
echo "rbenv already installed... skipping!" >&$log_fd 2>&1
fi
if [ ! -d "$RBENV_ROOT/versions" ]; then
echo "$RBENV_ROOT/versions doesn't exist ... creating..."
mkdir $RBENV_ROOT/versions >&$log_fd 2>&1
fi
if [ ! -d "$RBENV_ROOT/versions/$RUBY_VERSION" ]; then
echo "$RBENV_ROOT/versions/$RUBY_VERSION doesn't exist ... creating..." >&$log_fd 2>&1
mkdir $RBENV_ROOT/versions/$RBENV_VERSION >&$log_fd 2>&1
fi
# check if ruby version is installed
if [[ ! `rbenv version | grep $RUBY_VERSION` ]]; then
echo "installing ruby 2.1.4" >&$log_fd 2>&1
rbenv install $RUBY_VERSION >&$log_fd 2>&1
rbenv global $RUBY_VERSION >&$log_fd 2>&1
if [ ! -d "$RBENV_ROOT/versions/$RUBY_VERSION/etc" ]; then
echo "$RBENV_ROOT/versions/$RUBY_VERSION/etc doesn't exist ... creating..." >&$log_fd 2>&1
mkdir $RBENV_ROOT/versions/$RUBY_VERSION/etc >&$log_fd 2>&1
fi
else
echo "ruby $RUBY_VERSION already exists... skipping!" >&$log_fd 2>&1
fi
(( STATUS += 35 ))
echo $STATUS
}
While the install itself can fail at anytime on the new VM, I'm screwed if rbenv installs, but nothing else does (like ruby-build) or the $PATH, etc.
Would it make more sense to just encase every command in it's own if statement outside of the initial if which rbenv, or is there a more robust way to ensure the install completes successfully?

Answer 1

You can actually perform this task more easily using configuration management tools such as Ansible, puppet or Chef. Instead of trying to specify "how" to check and use endless IF statement, you can specify "what" to check and use existing framework to do so.
For example, in Ansible you can specify to update cache & install latest version of foo using apt module:
- hosts: all
remote_user: root
tasks:
- name: Install the package foo
apt:
name: foo
state: present
update_cache: yes
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