Multiple SIGHUPs in quick succession might cause the master keepalived
to forfeit its mastership (which will cause keepalived to remove IPs of
its external devices, severing connectivity). This can happen when, for
example, associating or disassociating multiple floatingips.
The patch makes the agent throttle SIGHUP sent to keepalived: the very first
SIGHUP is always sent; as for subsequent signals, they are delayed till
agent threshold is reached. (It's 3 seconds by default.)
As an example, when three consequent router updates trigger keepalived
respawn then:
* the very first signal is sent as usual;
* the second signal is deferred and sent in up to 3 seconds since the
first signal;
* the third signal is ignored, though the change that triggered it will
be correctly applied by the second signal handler when it is triggered
after threshold delay.
If the last time a spawn request occurred is older than current-time
minus threshold then there is no delay.
Co-Authored-By: Jakub Libosvar <libosvar@redhat.com>
Co-Authored-By: Cedric Brandily <zzelle@gmail.com>
Co-Authored-By: Ihar Hrachyshka <ihrachys@redhat.com>
Closes-Bug: 1647432
Change-Id: I2955e0de835458a2eea4dd088addf33b656f8670
977d254cc6