// Run blocks implementing the scheduler module.
func Run(conn db.Conn) {
var sched scheduler
for range conn.TriggerTick(30, db.MinionTable, db.EtcdTable, db.ContainerTable,
db.PlacementTable).C {
minion, err := conn.MinionSelf()
if err != nil || !conn.EtcdLeader() || minion.Role != db.Master ||
minion.PrivateIP == "" {
sched = nil
continue
}
if sched == nil {
ip := minion.PrivateIP
sched = newSwarm(docker.New(fmt.Sprintf("tcp://%s:2377", ip)))
time.Sleep(60 * time.Second)
}
placements := conn.SelectFromPlacement(nil)
connections := conn.SelectFromConnection(nil)
// Each time we run through this loop, we may boot or terminate
// containers. These modification should, in turn, be reflected in the
// database themselves. For this reason, we attempt to sync until no
// database modifications happen (up to an arbitrary limit of three
// tries).
for i := 0; i < 3; i++ {
dkc, err := sched.list()
if err != nil {
log.WithError(err).Warning("Failed to get containers.")
break
}
var boot []db.Container
var term []string
conn.Transact(func(view db.Database) error {
term, boot = syncDB(view, dkc)
return nil
})
if len(term) == 0 && len(boot) == 0 {
break
}
sched.terminate(term)
sched.boot(boot, placements, connections)
}
}
}