before commit, check if puppet files have valid syntax

pre-commit

#!/bin/sh
# this hook aborts commits which contain invalid puppet syntax 

errors=0

# get all files in commit, use awk to get file name only, use grep to get puppet files only
files=$(git diff --cached --name-status | awk '$1 != "D" { print $2 }' | grep "\.pp")

# if you are committing .pp files
if [[ "$files" ]]; then

    # if puppet is not found, warn the user and exit (don't show output)
    $(which puppet &> /dev/null)
    if [[ $? != 0 ]]; then
        echo "'which puppet' did not find puppet comand."
        echo "to validate puppet syntax please install puppet."
        echo "To override this check add the --no-verify flag "
        exit 1
    fi

    while read -r pp_file; do
        echo "Validating: puppet parser validate $pp_file"
        
        # assign output from stdout and stderr to var
        cmd_out=$(puppet parser validate $pp_file 2>&1)

        # parser should output nothing if successful
        # if parser outputs anything, increment errors   
        if [[ "$cmd_out" ]]; then
            let errors=errors+1        

            # send output to stderr
            (>&2 echo "$cmd_out")
        fi
    done <<< "$files"
    # while executes in subshell so use <<< to get access to errors variable
fi

# if any of the files about to be committed did not pass the syntax validation, exit the commit
if [[ $errors != 0 ]]; then
    echo "Aborting commit due to $errors puppet syntax errors."
    exit 1
fi