commit-msg

#!/usr/bin/env bash

# Example commit-msg hook written in bash
# (c) 2016 Brent Laster

# define our error messages
error_msg1="Error: Commit message is too small."
error_msg2="Error: Commit message cannot be the same as the previous commit message."
error_msg3="Error: Expected text not in commit message:"
abort_msg="Commit will not be allowed due to error."
minimum_length=25

# just exit if we don't have any arguments
[ "$1" ] || exit 1

# read the contents of the temp commit message file and get the length of it
contents=$(<"$1")
size=${#contents}

# if the message is too short, error out
if [ $size -le $minimum_length ]; then
	echo "$error_msg1" >&2
	echo "$abort_msg" >&2
	exit 1
fi

# if we have a previous revision, make sure we're not using the same message as the last commit
if git rev-parse --verify HEAD >/dev/null 2>&1
then
    previous_log_msg=$(git show -s --format=%s)
	if [ "$previous_log_msg" == "$contents" ]; then
		echo "$error_msg2" >&2
		echo "$abort_msg" >&2
		exit 1
	fi
fi

# if our branch is master or starts with "prod" or "ship"
#  check to make sure we have the value defined in user.msg in the commit message
branch=$(git symbolic-ref --short HEAD)
if [[ $branch =~ ^master$|^(prod|ship).*$ ]]; then
	iuo_msg=$(git config user.msg)
	if ! grep -iqE "$iuo_msg" "$1"; then
		echo "$error_msg3" "$iuo_msg" >&2
		echo "$abort_msg" >&2
		exit 1
	fi
fi	

# Redirect output to stderr.
exec 1>&2

exit 0