timeserver

noun

Etymology: From time + server.

1. 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.”

2. Someone who performs a job for the required time only, making a minimum of effort.
3. A device, node or program that transmits the correct time to clients in a network.
4. Someone who honors their commitments only when it is personally easy to do so.