Because a running service does not re-read its configuration. Replace the file,
find the service running, do nothing -- and the machine keeps behaving as it
did while every check passes, because the file is right and the service is up.
That is not hypothetical. It is how a third node joining a mesh left the first
two carrying a private network that no longer existed, with every part of it
reporting success.
Declared state rather than a command: the declaration says the running service
must reflect these files, and the host works out that it does not. A command to
restart would be an action, and the link may not carry one -- the host refused
precisely that when I tried it, correctly, which is how this shape was arrived
at rather than the other.
Scoped to one apply. A change from an earlier one has already been reflected,
and restarting for it every time would make a steady machine bounce its
services for ever.
Also: the node generates its overlay key at enrolment and reports the public
half, and the store waits three minutes rather than one for the database --
sixty seconds is not enough for a cold machine running initdb, and it failed
that way three times, which is the worst kind of flake because a second run
always fixed it.
jschoubben
1bc97ed50d