func()

in providers/gce/gce_loadbalancer_internal.go [546:614]
53 lines of code
15 McCabe index (conditional complexity)

func (g *Cloud) ensureInternalInstanceGroup(name, zone string, nodes []*v1.Node) (string, error) {
	klog.V(2).Infof("ensureInternalInstanceGroup(%v, %v): checking group that it contains %v nodes", name, zone, len(nodes))
	ig, err := g.GetInstanceGroup(name, zone)
	if err != nil && !isNotFound(err) {
		return "", err
	}

	kubeNodes := sets.NewString()
	for _, n := range nodes {
		kubeNodes.Insert(n.Name)
	}

	// Individual InstanceGroup has a limit for 1000 instances in it.
	// As a result, it's not possible to add more to it.
	// Given that the long-term fix (AlphaFeatureILBSubsets) is already in-progress,
	// to stop the bleeding we now simply cut down the contents to first 1000
	// instances in the alphabetical order. Since there is a limitation for
	// 250 backend VMs for ILB, this isn't making things worse.
	if len(kubeNodes) > maxInstancesPerInstanceGroup {
		klog.Warningf("Limiting number of VMs for InstanceGroup %s to %d", name, maxInstancesPerInstanceGroup)
		kubeNodes = sets.NewString(kubeNodes.List()[:maxInstancesPerInstanceGroup]...)
	}

	gceNodes := sets.NewString()
	if ig == nil {
		klog.V(2).Infof("ensureInternalInstanceGroup(%v, %v): creating instance group", name, zone)
		newIG := &compute.InstanceGroup{Name: name}
		if err = g.CreateInstanceGroup(newIG, zone); err != nil {
			return "", err
		}

		ig, err = g.GetInstanceGroup(name, zone)
		if err != nil {
			return "", err
		}
	} else {
		instances, err := g.ListInstancesInInstanceGroup(name, zone, allInstances)
		if err != nil {
			return "", err
		}

		for _, ins := range instances {
			parts := strings.Split(ins.Instance, "/")
			gceNodes.Insert(parts[len(parts)-1])
		}
	}

	removeNodes := gceNodes.Difference(kubeNodes).List()
	addNodes := kubeNodes.Difference(gceNodes).List()

	if len(removeNodes) != 0 {
		klog.V(2).Infof("ensureInternalInstanceGroup(%v, %v): removing nodes: %v", name, zone, removeNodes)
		instanceRefs := g.ToInstanceReferences(zone, removeNodes)
		// Possible we'll receive 404's here if the instance was deleted before getting to this point.
		if err = g.RemoveInstancesFromInstanceGroup(name, zone, instanceRefs); err != nil && !isNotFound(err) {
			return "", err
		}
	}

	if len(addNodes) != 0 {
		klog.V(2).Infof("ensureInternalInstanceGroup(%v, %v): adding nodes: %v", name, zone, addNodes)
		instanceRefs := g.ToInstanceReferences(zone, addNodes)
		if err = g.AddInstancesToInstanceGroup(name, zone, instanceRefs); err != nil {
			return "", err
		}
	}

	return ig.SelfLink, nil
}