A tag name must be valid ASCII and may contain lowercase and uppercase letters, digits, underscores, periods and dashes. A tag name may not start with a period or a dash and may contain a maximum of 128 characters
CI_COMMIT_REF_SLUG :CI_COMMIT_REF_NAME in lowercase, shortened to 63 bytes, and with everything except 0-9 and a-z replaced with -. No leading / trailing -. Use in URLs, host names and domain names.