// NextOp is defined on the Resolver interface.
func (l *leadershipResolver) NextOp(
localState resolver.LocalState,
remoteState remotestate.Snapshot,
opFactory operation.Factory,
) (operation.Operation, error) {
// TODO(wallyworld) - maybe this can occur before install
if !localState.Installed {
return nil, resolver.ErrNoOperation
}
// Check for any leadership change, and enact it if possible.
logger.Infof("checking leadership status")
// If we've already accepted leadership, we don't need to do it again.
canAcceptLeader := !localState.Leader
if remoteState.Life == params.Dying {
canAcceptLeader = false
} else {
// If we're in an unexpected mode (eg pending hook) we shouldn't try either.
if localState.Kind != operation.Continue {
canAcceptLeader = false
}
}
switch {
case remoteState.Leader && canAcceptLeader:
return opFactory.NewAcceptLeadership()
// If we're the leader but should not be any longer, or
// if the unit is dying, we should resign leadership.
case localState.Leader && (!remoteState.Leader || remoteState.Life == params.Dying):
return opFactory.NewResignLeadership()
}
if localState.Kind == operation.Continue {
// We want to run the leader settings hook if we're
// not the leader and the settings have changed.
if !localState.Leader && localState.LeaderSettingsVersion != remoteState.LeaderSettingsVersion {
return opFactory.NewRunHook(hook.Info{Kind: hook.LeaderSettingsChanged})
}
}
logger.Infof("leadership status is up-to-date")
return nil, resolver.ErrNoOperation
}