Assigns default=true on a multiple interface return for first interfa…

…ce with a gateway

This is necessary especially under crio, as you may not want to present the default gateway interfaces IP address as the first CNI response, as crio utilizes that IP address as the PodIP, so you may need flexibility in expression of which interface should be presented first, vs. another interface which should be the default gateway (which we mark as default=true in the network-status)

pkg/utils/net-attach-def.go

@@ -152,14 +152,41 @@ func CreateNetworkStatuses(r cnitypes.Result, networkName string, defaultNetwork
 	// Same for DNS
 	v1dns := convertDNS(result.DNS)
 
+	// Check for a gateway-associated interface, we'll use this later if we did to mark as the default.
+	gatewayInterfaceIndex := -1
+	if defaultNetwork {
+		for _, ipConfig := range result.IPs {
+			if ipConfig.Gateway != nil && ipConfig.Interface != nil {
+				// Keep the index of the first interface that has a gateway
+				gatewayInterfaceIndex = *ipConfig.Interface
+				break
+			}
+		}
+	}
+
 	// Initialize NetworkStatus for each container interface (e.g. with sandbox present)
 	indexOfFoundPodInterface := 0
 	foundFirstSandboxIface := false
+	didSetDefault := false
 	for i, iface := range result.Interfaces {
 		if iface.Sandbox != "" {
+			isDefault := false // default to false by default
+
+			// If there's a gateway listed for this interface index found in the ips, we mark that interface as default
+			// notably, we use the first one we find.
+			if defaultNetwork && i == gatewayInterfaceIndex && !didSetDefault {
+				isDefault = true
+				didSetDefault = true
+			}
+
+			// Otherwise, if we didn't find it, we use the first sandbox interface.
+			if defaultNetwork && gatewayInterfaceIndex == -1 && !foundFirstSandboxIface {
+				isDefault = true
+			}
+
 			ns := &v1.NetworkStatus{
 				Name:       networkName,
-				Default:    defaultNetwork && !foundFirstSandboxIface,
+				Default:    isDefault,
 				Interface:  iface.Name,
 				Mac:        iface.Mac,
 				Mtu:        iface.Mtu,

pkg/utils/net-attach-def_test.go

@@ -101,6 +101,62 @@ var _ = Describe("Netwok Attachment Definition manipulations", func() {
 		Expect(fakeStatus).To(Equal(getStatuses))
 	})
 
+	It("matches default=true when gateway is present for an interface", func() {
+		// CNI result using cni100.Result format
+		ifone := 1
+		iftwo := 3
+		cniResult := &cni100.Result{
+			CNIVersion: "1.0.0",
+			Interfaces: []*cni100.Interface{
+				{
+					Name: "0xsomething",
+					Mac:  "be:ee:ee:ee:ee:ef",
+				},
+				{
+					Name:    "eth0",
+					Mac:     "b1:aa:aa:aa:a5:ee",
+					Sandbox: "/var/run/netns/cni-309e7579-1b15-f905-5150-2cd232b0dad9",
+				},
+				{
+					Name: "0xotherthing",
+					Mac:  "b0:00:00:00:00:0f",
+				},
+				{
+					Name:    "other-primary",
+					Mac:     "c0:00:00:00:00:01",
+					Sandbox: "/var/run/netns/cni-309e7579-1b15-f905-5150-2cd232b0dad9",
+				},
+			},
+			IPs: []*cni100.IPConfig{
+				{
+					Interface: &ifone,
+					Address:   *EnsureCIDR("10.244.1.6/24"),
+				},
+				{
+					Interface: &iftwo,
+					Address:   *EnsureCIDR("10.20.1.3/24"),
+					Gateway:   net.ParseIP("10.20.1.1"),
+				},
+			},
+		}
+
+		// Call CreateNetworkStatuses with this CNI result
+		networkName := "test-network"
+		defaultNetwork := true
+		deviceInfo := &v1.DeviceInfo{} // mock device info if needed
+
+		networkStatuses, err := CreateNetworkStatuses(cniResult, networkName, defaultNetwork, deviceInfo)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(networkStatuses).To(HaveLen(2)) // expecting 2 statuses for sandboxed interfaces
+
+		// Check that the interface with the gateway is marked as default
+		Expect(networkStatuses[0].Interface).To(Equal("eth0"))
+		Expect(networkStatuses[0].Default).To(BeFalse())
+
+		Expect(networkStatuses[1].Interface).To(Equal("other-primary"))
+		Expect(networkStatuses[1].Default).To(BeTrue()) // other-primary should be default because it has a gateway
+	})
+
 	Context("create network status from cni result", func() {
 		var cniResult *cni100.Result
 		var networkStatus *v1.NetworkStatus