fix: skip gw IP check for DPU and improve gateway initialization readability

Skip GW IP check in case ovnkube is running in DPU mode.

Extract interface address logic into dedicated helper function to improve
code readability and maintainability in gateway initialization.

- Add getInterfaceAddressesForNodeMode() helper function
- Replace conditional logic with switch statement for better extensibility
- Simplify initGatewayPreStart() by removing duplicate error handling
- Improve code organization and reduce cognitive complexity

Signed-off-by: Alin Gabriel Serdean <[email protected]>
Signed-off-by: Alin Serdean <[email protected]>

Author: aserdean

go-controller/pkg/node/gateway_init.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/vishvananda/netlink"
 
-	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/klog/v2"
 	utilnet "k8s.io/utils/net"
@@ -188,6 +187,39 @@ func configureSvcRouteViaInterface(routeManager *routemanager.Controller, iface
 	return nil
 }
 
+// getNodePrimaryIfAddrs returns the appropriate interface addresses based on the node mode
+func getNodePrimaryIfAddrs(watchFactory factory.NodeWatchFactory, nodeName string, gatewayIntf string) ([]*net.IPNet, error) {
+	switch config.OvnKubeNode.Mode {
+	case types.NodeModeDPU:
+		// For DPU mode, use the host IP address from node annotation
+		node, err := watchFactory.GetNode(nodeName)
+		if err != nil {
+			return nil, fmt.Errorf("error retrieving node %s: %v", nodeName, err)
+		}
+
+		// Extract the primary DPU address annotation from the node
+		nodeIfAddr, err := util.GetNodePrimaryDPUHostAddrAnnotation(node)
+		if err != nil {
+			return nil, err
+		}
+
+		if nodeIfAddr.IPv4 == "" {
+			return nil, fmt.Errorf("node primary DPU address annotation is empty for node %s", nodeName)
+		}
+
+		nodeIP, nodeAddrs, err := net.ParseCIDR(nodeIfAddr.IPv4)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse node IP address %s: %v", nodeIfAddr.IPv4, err)
+		}
+
+		nodeAddrs.IP = nodeIP
+		return []*net.IPNet{nodeAddrs}, nil
+	default:
+		// For other modes, get network interface IP addresses directly
+		return nodeutil.GetNetworkInterfaceIPAddresses(gatewayIntf)
+	}
+}
+
 // initGatewayPreStart executes the first part of the gateway initialization for the node.
 // It creates the gateway object, the node IP manager, openflow manager and node port watcher
 // once OVN controller is ready and the patch port exists for this node.
@@ -215,46 +247,12 @@ func (nc *DefaultNodeNetworkController) initGatewayPreStart(
 		egressGWInterface = interfaceForEXGW(config.Gateway.EgressGWInterface)
 	}
 
-	ifAddrs, err = nodeutil.GetNetworkInterfaceIPAddresses(gatewayIntf)
+	// Get interface addresses based on node mode
+	ifAddrs, err = getNodePrimaryIfAddrs(nc.watchFactory, nc.name, gatewayIntf)
 	if err != nil {
 		return nil, err
 	}
 
-	// For DPU mode, we need to use the host IP address which is stored as a Kubernetes
-	// node annotation rather than using the gateway interface IP addresses.
-	if config.OvnKubeNode.Mode == types.NodeModeDPU {
-		// Retrieve the current node object from the Kubernetes API
-		var node *corev1.Node
-		if node, err = nc.watchFactory.GetNode(nc.name); err != nil {
-			return nil, fmt.Errorf("error retrieving node %s: %v", nc.name, err)
-		}
-
-		// Extract the primary DPU address annotation from the node
-		nodeIfAddr, err := util.GetNodePrimaryDPUHostAddrAnnotation(node)
-		if err != nil {
-			return nil, err
-		}
-		// For DPU mode, we only support IPv4 for now.
-		nodeAddrStr := nodeIfAddr.IPv4
-		if nodeAddrStr == "" {
-			return nil, fmt.Errorf("node primary DPU address annotation is empty for node %s", nc.name)
-		}
-
-		// Parse the IPv4 address string into IP and network components
-		nodeIP, nodeAddrs, err := net.ParseCIDR(nodeAddrStr)
-		if err != nil {
-			return nil, fmt.Errorf("failed to parse node IP address %s: %v", nodeAddrStr, err)
-		}
-
-		// Set the parsed IP as the network address
-		nodeAddrs.IP = nodeIP
-
-		// Create a new slice and replace ifAddrs with the DPU host address
-		// This overrides the gateway interface addresses for DPU mode
-		var gwIps []*net.IPNet
-		ifAddrs = append(gwIps, nodeAddrs)
-	}
-
 	if err := util.SetNodePrimaryIfAddrs(nodeAnnotator, ifAddrs); err != nil {
 		klog.Errorf("Unable to set primary IP net label on node, err: %v", err)
 	}