Monitor Kubernetes for New Provider Host Custom Resources

The ObserveHostnameState function - located within provider/cluster/kube/client_hostname_connections.go - monitors for new providerhost custom resource adds, updates, or deletes.

The ObserveHostnameState method returns new events on a channel which is then taken off the channel within a select block.

Finally the event - stored in the ev variable once it is pulled off the channel - is passed into the applyEvent method.

    ....
    
    events, err := op.client.ObserveHostnameState(ctx)
    if err != nil {
        cancel()
        return err
    }

loop:
    for {
        select {
        ....

        case ev, ok := <-events:
            if !ok {
                exitError = operatorcommon.ErrObservationStopped
                break loop
            }
            err = op.applyEvent(ctx, ev)
            if err != nil {
                op.log.Error("failed applying event", "err", err)
                exitError = err
                break loop
            }
        case <-pruneTicker.C:
            op.prune()
        case <-prepareTicker.C:
            if err := op.server.PrepareAll(); err != nil {
                op.log.Error("preparing web data failed", "err", err)
            }

        }
    }

    cancel()
    op.log.Debug("hostname operator done")
    return exitError