CircleCI precommit hook

pre-commit

#!/usr/bin/env bash
# Slightly modified from: https://circleci.com/blog/circleci-hacks-validate-circleci-config-on-every-commit-with-a-git-hook/

# The following line is needed by the CircleCI Local Build Tool (due to Docker interactivity)
exec < /dev/tty

# Only validate if we've changed the .circleci/config.yml file
if git diff --cached --name-only | grep --quiet ".circleci/config.yml"; then
  # Make sure we have the circleci utility installed
  # https://circleci.com/docs/local-cli
  circleci_path=$(which circleci)
  return_code=$?
  if [ ${return_code} -eq 0 ]; then
    # If validation fails, tell Git to stop and provide error message. Otherwise, continue.
    if ! eMSG=$(circleci config validate -c .circleci/config.yml); then
      echo "CircleCI Configuration Failed Validation."
      echo $eMSG
      exit 1
    fi
  else
    echo "circleci utility not found, so we can't validate the changed config file."
    sleep 2
  fi
fi