func (c *upgradeWorkerContext) waitForOtherStateServers(info *state.UpgradeInfo) error { watcher := info.Watch() defer watcher.Stop() maxWait := getUpgradeStartTimeout(c.isMaster) timeout := time.After(maxWait) for { select { case <-watcher.Changes(): if err := info.Refresh(); err != nil { return errors.Trace(err) } if c.isMaster { if ready, err := info.AllProvisionedStateServersReady(); err != nil { return errors.Trace(err) } else if ready { // All state servers ready to start upgrade err := info.SetStatus(state.UpgradeRunning) return errors.Trace(err) } } else { if info.Status() == state.UpgradeFinishing { // Master is done, ok to proceed return nil } } case <-timeout: if c.isMaster { if err := info.Abort(); err != nil { return errors.Annotate(err, "unable to abort upgrade") } } return errors.Errorf("timed out after %s", maxWait) case <-c.agent.Dying(): return agentTerminating } } }