func startNodeIpamController()

in cmd/cloud-controller-manager/nodeipamcontroller.go [69:164]
69 lines of code
20 McCabe index (conditional complexity)

func startNodeIpamController(ccmConfig *cloudcontrollerconfig.CompletedConfig, nodeIPAMConfig nodeipamconfig.NodeIPAMControllerConfiguration, ctx genericcontrollermanager.ControllerContext, cloud cloudprovider.Interface) (controller.Interface, bool, error) {
	var serviceCIDR *net.IPNet
	var secondaryServiceCIDR *net.IPNet

	// should we start nodeIPAM
	if !ccmConfig.ComponentConfig.KubeCloudShared.AllocateNodeCIDRs {
		return nil, false, fmt.Errorf("the AllocateNodeCIDRs is not enabled")
	}

	// failure: bad cidrs in config
	clusterCIDRs, dualStack, err := processCIDRs(ccmConfig.ComponentConfig.KubeCloudShared.ClusterCIDR)
	if err != nil {
		return nil, false, err
	}

	// failure: more than one cidr and dual stack is not enabled
	if len(clusterCIDRs) > 1 && !utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack) {
		return nil, false, fmt.Errorf("len of ClusterCIDRs==%v and dualstack feature is not enabled", len(clusterCIDRs))
	}

	// failure: more than one cidr but they are not configured as dual stack
	if len(clusterCIDRs) > 1 && !dualStack {
		return nil, false, fmt.Errorf("len of ClusterCIDRs==%v and they are not configured as dual stack (at least one from each IPFamily", len(clusterCIDRs))
	}

	// failure: more than cidrs is not allowed even with dual stack
	if len(clusterCIDRs) > 2 {
		return nil, false, fmt.Errorf("len of clusters is:%v > more than max allowed of 2", len(clusterCIDRs))
	}

	// service cidr processing
	if len(strings.TrimSpace(nodeIPAMConfig.ServiceCIDR)) != 0 {
		_, serviceCIDR, err = net.ParseCIDR(nodeIPAMConfig.ServiceCIDR)
		if err != nil {
			klog.Warningf("Unsuccessful parsing of service CIDR %v: %v", nodeIPAMConfig.ServiceCIDR, err)
		}
	}

	if len(strings.TrimSpace(nodeIPAMConfig.SecondaryServiceCIDR)) != 0 {
		_, secondaryServiceCIDR, err = net.ParseCIDR(nodeIPAMConfig.SecondaryServiceCIDR)
		if err != nil {
			klog.Warningf("Unsuccessful parsing of service CIDR %v: %v", nodeIPAMConfig.SecondaryServiceCIDR, err)
		}
	}

	// the following checks are triggered if both serviceCIDR and secondaryServiceCIDR are provided
	if serviceCIDR != nil && secondaryServiceCIDR != nil {
		// should have dual stack flag enabled
		if !utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack) {
			return nil, false, fmt.Errorf("secondary service cidr is provided and IPv6DualStack feature is not enabled")
		}

		// should be dual stack (from different IPFamilies)
		dualstackServiceCIDR, err := netutils.IsDualStackCIDRs([]*net.IPNet{serviceCIDR, secondaryServiceCIDR})
		if err != nil {
			return nil, false, fmt.Errorf("failed to perform dualstack check on serviceCIDR and secondaryServiceCIDR error:%v", err)
		}
		if !dualstackServiceCIDR {
			return nil, false, fmt.Errorf("serviceCIDR and secondaryServiceCIDR are not dualstack (from different IPfamiles)")
		}
	}

	var nodeCIDRMaskSizeIPv4, nodeCIDRMaskSizeIPv6 int
	if utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack) {
		// only --node-cidr-mask-size-ipv4 and --node-cidr-mask-size-ipv6 supported with dual stack clusters.
		// --node-cidr-mask-size flag is incompatible with dual stack clusters.
		nodeCIDRMaskSizeIPv4, nodeCIDRMaskSizeIPv6, err = setNodeCIDRMaskSizesDualStack(nodeIPAMConfig)
	} else {
		// only --node-cidr-mask-size supported with single stack clusters.
		// --node-cidr-mask-size-ipv4 and --node-cidr-mask-size-ipv6 flags are incompatible with dual stack clusters.
		nodeCIDRMaskSizeIPv4, nodeCIDRMaskSizeIPv6, err = setNodeCIDRMaskSizes(nodeIPAMConfig)
	}

	if err != nil {
		return nil, false, err
	}

	// get list of node cidr mask sizes
	nodeCIDRMaskSizes := getNodeCIDRMaskSizes(clusterCIDRs, nodeCIDRMaskSizeIPv4, nodeCIDRMaskSizeIPv6)

	nodeIpamController, err := nodeipamcontroller.NewNodeIpamController(
		ctx.InformerFactory.Core().V1().Nodes(),
		cloud,
		ctx.ClientBuilder.ClientOrDie("node-controller"),
		clusterCIDRs,
		serviceCIDR,
		secondaryServiceCIDR,
		nodeCIDRMaskSizes,
		ipam.CIDRAllocatorType(ccmConfig.ComponentConfig.KubeCloudShared.CIDRAllocatorType),
	)
	if err != nil {
		return nil, false, err
	}
	go nodeIpamController.Run(ctx.Stop)
	return nil, true, nil
}