A Git pre-commit hook for Puppet to validate syntax and style

puppet-pre-commit.sh

#!/bin/bash

# Description: A Git pre-commit hook for Puppet manifests
# Validates Puppet manifest syntax amd style 
#  * Syntax validation: Using puppet parser as documented on Puppet wiki
#   - http://projects.puppetlabs.com/projects/1/wiki/Puppet_Version_Control
#  * Style validation: Using puppet lint

# Requirements:
#  * Ruby 1.8.7
#  * Puppet 2.7
#  * puppte-lint
#  * rspec-puppet (seems like puppet 2.7 requires it, the hook doesn't use it)

# I have installed Puppet gems in my dev envrionment using rvm, but you can use
# this hook with system installed Puppet and system wide gem installations as
# well. You will need to modify script according to your Puppet/gem 
# environment.

# Author: Shantanu Pavgi, pavgi@uab.edu

# Load RVM and puppet gemsets
. $HOME/bashrc/rvm
rvm use 1.8.7
rvm gemset use puppet

# Stash modifications done after file(s) were added to the index
# Check contents that are currently indexed
git stash -q --keep-index
syntax_errors=0
style_errors=0
error_msg=$(mktemp /tmp/error_msg.XXXXXX)

# prepare diff context 
if git rev-parse --quiet --verify HEAD > /dev/null
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# remove empty files from given file array and return modified array
function remove_empty_files(){
  # passing/reading array parameter like this will be buggy - IF - multiple
  # arrays are being passed. However, it's okay for this script as params
  # are being passed within the script and we are aware of the issue!
  indexfiles="${@}"
  indexfiles_cur=()
  for indexfile in $indexfiles; do
    if [ `git cat-file -s :0:$indexfile` == "0" ]; then
      indexfiles_cur+=${indexfiles/${indexfile}/}
    fi
  done
  echo "${indexfiles_cur[@]}"
}


# Check puppet syntax
# Accept file array and validate each file's syntax based on it's file type
function check_syntax(){
  indexfiles="${@}"
  for indexfile in $indexfiles; do
    case $indexfile in
      *.pp )
        # Check puppet manifest syntax
        # git cat-file blob :0:$indexfile | puppet --color=false --parseonly --ignoreimport > $error_msg ;;
        # Updated for 2.7.x
        puppet parser validate $indexfile > $error_msg ;;
      *.erb )
        # Check ERB template syntax
        # -P : ignore lines which start with "%" 
        git cat-file blob :0:$indexfile | erb -P -x -T - | ruby -c 2> $error_msg > /dev/null ;;
      *)
        echo "Unsupported file name extension. Style validation is performed only for *.pp files";;
    esac
    # if exit code is non-zero then display error message
    if [ "$?" -ne 0 ]; then
      echo -n "$indexfile: "
      cat $error_msg
      syntax_errors=`expr $syntax_errors + 1`
    fi
  done
  # remove error_msg from last iteration
  rm -f $error_msg
  # Return non-zero exit code if syntax errors are present
  if [ "$syntax_errors" -ne 0 ]; then
    echo "Error: $syntax_errors syntax errors found, aborting commit."
    return 1
  fi
  return 0
}

# validate puppet style of staged manifest (*.pp) files using puppet lint
function check_style(){
  indexfiles="${@}"
  for indexfile in $indexfiles; do
    case $indexfile in
      *.pp )
        puppet-lint $indexfile > $error_msg ;;
      *)
        echo "Unsupported file name extension. Style validation is performed only for *.pp files" ;;
    esac
    # Return non-zero exit code if style errors are present
    if [ "$?" -ne 0 ]; then
      echo -n "$indexfile: "
      cat $error_msg
      style_errors=`expr $style_errors + 1`
    fi
  done

  # remove error_msg from last iteration
  rm -f $error_msg
  # Return non-zero exit code if style validations fail
  if [ "$style_errors" -ne 0 ]; then
    echo "Error: $style_errors style errors found, aborting commit."
    return 1
  fi
  return 0
}


# Get list of new/modified manifest and template files to check (in git index)
pp_files=`git diff-index --diff-filter=AM --name-only --cached $against | egrep '\.pp'`
erb_files=`git diff-index --diff-filter=AM --name-only --cached $against | egrep '\.erb'`
# Remove empty files - empty files will be skipped from validation!
pp_files=( `remove_empty_files $pp_files` )
erb_files=( `remove_empty_files $erb_files` )
all_files=( ${pp_files[@]} ${erb_files[@]} )
# check style errors only if there are no syntax errors
check_syntax "${all_files[@]}" && check_style "${pp_files[@]}"
# exit with exit code 1 in case of errors
# unstash changes in both cases
if [ $? -eq 0 ]; then
  git stash pop -q
else
  exit 1
  git stash pop -q
fi