Perform setuid/setgid in grokmirror itself

We want to make it possible to run grok-pull as multiple users, so make
that configurable via loadable EnvironmentFile's and perform
setuid/setgid inside grokmirror itself instead of deferring that to
systemd.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
6 files changed