netlify-ignore.sh

#! /bin/bash

# netlify-ignore.sh
# logic based shell script for the Netlify based on enivonment variables
# exiting script with code 1 means build, code 0 means no changes so cancel

# Optional Environmental Inputs:
# ALWAYS_BUILD: true,yes,on,1
#   forces an always build
# WATCHED_BUILD_PATHS: example ( "../../common" )
#   space separated paths to append to the default git diff statement

# Required Inputs Supplied from Netlify build environment variables
# CACHED_COMMIT_REF
# COMMIT_REF
# SITE_NAME

# Function to display usage
usage() {
  echo -e "\033[1;33mUsage: $0 [--no-default-path]\033[0m"
  echo -e "\033[1;33mDefault watch build path is set to '.' before other paths are included.\033[0m"
  exit 0  # Exit script after printing usage and do not trigger a build
}

# Parse optional flag
DEFAULT_WATCH_BUILD_PATH="."
while [[ "$1" != "" ]]; do
  case $1 in
    --no-default-path ) DEFAULT_WATCH_BUILD_PATH="" # remove default path
                        ;;
    -h | --help )       usage
                        ;;
    * )                 usage
                        ;;
  esac
  shift
done

set -x
shopt -s nocasematch
regex="^(build|deploy|build $SITE_NAME|deploy $SITE_NAME)$"

if [[ ! "$WATCHED_BUILD_PATHS" =~ (false|no|off|0) ]]; then BUILD_PATHS="$WATCHED_BUILD_PATHS"; fi;
# shellcheck disable=SC2046
if [[ "$ALWAYS_BUILD" =~ (true|yes|on|1) ]]; then (exit 1);
elif [ "$CACHED_COMMIT_REF" == "$COMMIT_REF" ]; then (exit 1);
elif [[ $(git rev-parse "$COMMIT_REF^{tree}") == $(git rev-parse "$COMMIT_REF^1^{tree}") && $(git -P show -s "$COMMIT_REF" --format=%s ) =~  $regex ]]; then (exit 1);
else git diff --quiet "$CACHED_COMMIT_REF" "$COMMIT_REF" $([[ -n "$DEFAULT_WATCH_BUILD_PATH" ]] && echo "$DEFAULT_WATCH_BUILD_PATH ")$([[ -n "$BUILD_PATHS" ]] && echo " $BUILD_PATHS"); fi;