Server-side pre-receive hook to validate puppet files.

pre-receive-puppet

#!/bin/bash

COMMAND='puppet parser validate'
TEMPDIR=`mktemp -d`

echo "### Attempting to validate puppet files... ####"

# See https://www.kernel.org/pub/software/scm/git/docs/githooks.html#pre-receive    
oldrev=$1
newrev=$2
refname=$3

while read oldrev newrev refname; do
    
    # Get the file names, without directory, of the files that have been modified
    # between the new revision and the old revision
    files=`git diff --name-only ${oldrev} ${newrev}`

    # Get a list of all objects in the new revision
    objects=`git ls-tree --full-name -r ${newrev}`

    # Iterate over each of these files
    for file in ${files}; do
  
        # Search for the file name in the list of all objects
        object=`echo -e "${objects}" | egrep "(\s)${file}\$" | awk '{ print $3 }'`
        
        # If it's not present, then continue to the the next itteration
        if [ -z ${object} ]; 
	then 
	    continue; 
	fi

        # Otherwise, create all the necessary sub directories in the new temp directory
        mkdir -p "${TEMPDIR}/`dirname ${file}`" &>/dev/null
        # and output the object content into it's original file name
	git cat-file blob ${object} > ${TEMPDIR}/${file}
	
    done;
done

# Now loop over each file in the temp dir to parse them for valid syntax
files_found=`find ${TEMPDIR} -name '*.pp'`
for fname in ${files_found}; do
    ${COMMAND} ${fname}
    if [[ $? -ne 0 ]];
    then
	  echo "ERROR: parser failed on ${fname}" 
          bad_file=1
    fi
done;

rm -rf ${TEMPDIR} &> /dev/null

if [[ $bad_file -eq 1 ]]
then
  exit 1
fi

Rather search for a file's object and then retrieve the object, in a similar situation I chose to directly retrieve the file from the revision using git-show
git show ${newrev}:${file} > ${TEMPDIR}/${file}