bash essentials

essentials.bash

# Check for arbitrary environment variables
UNSET_ENVS=false
function check_env() {
  if [ -z "${!1}" ]; then
    >&2 echo "ERROR: Environment Variable '$1' is not set"
    export UNSET_ENVS=true
  else
    echo "$1 set to ${!1}"
  fi
}
check_env WAIT_FOR_FILE_TO_EXIST_TIMEOUT_SECONDS
check_env SOURCE_FILENAME
check_env TARGET_S3_BUCKET
check_env TARGET_S3_PREFIX
check_env TARGET_S3_FILENAME
if $UNSET_ENVS; then
  >&2 echo "FATAL: Correct missing environment variables, then restart container"
  exit 1
else
  echo All environment variables set correctly
fi