An electronic straight shackle lock apparatus and system. Aspects of the present disclosure provide for a keyless, electronic straight shackle lock that provides a high level of security at a relatively low cost and without any opening for a physical mechanical key. Certain embodiments provide for an easy-to-use and compact adapter for a keyless, electronic straight shackle lock and the ability to manually override the electronic lock. Certain benefits and advantages of the present disclosure include a compact and flexible locking system that can be installed on many different enclosures and doors that can be locked and unlocked using an electronic device via a wireless signal.