timeserver

A person who conforms to current opinions, especially for reasons of personal advantage; an opportunist.

Another of Lilly's confidants was the time-server, John Gauden, who was distinctly anti-Laudian in outlook, but who nevertheless became Bishop of Worcester at the Restoration.

Someone who performs a job for the required time only, making a minimum of effort.

A device, node or program that transmits the correct time to clients in a network.

Someone who honors their commitments only when it is personally easy to do so.