fix(xdp): Start the edge gateway and NAT on bonded hosts

internal/plumbing/ebpf/xdpmode/mode.go

@@ -116,7 +116,8 @@ var sysClassNet = "/sys/class/net"
 // target and has no driver link at all, as while its driver unbinds, carries
 // no driver traffic; it is left out and listed in Skipped. An interface with
 // no device link, such as a bond master, a veth or a VLAN, is virtual and has
-// no driver of its own to consider.
+// no driver of its own to consider. A regular file, such as the bonding
+// driver's bonding_masters, is not an interface.
 func Select(required ...string) (Decision, error) {
 	entries, err := os.ReadDir(sysClassNet)
 	if err != nil {
@@ -129,6 +130,9 @@ func Select(required ...string) (Decision, error) {
 		skipped []string
 	)
 	for _, e := range entries {
+		if e.Type().IsRegular() {
+			continue
+		}
 		name := e.Name()
 		present[name] = true
 		driver, physical, err := interfaceDriver(name)

internal/plumbing/ebpf/xdpmode/mode_test.go

@@ -82,6 +82,15 @@ func (f *fakeSysfs) virtual(name string) {
 	}
 }
 
+// file adds a regular file, the way the bonding driver adds bonding_masters
+// beside the interfaces.
+func (f *fakeSysfs) file(name string) {
+	f.t.Helper()
+	if err := os.WriteFile(filepath.Join(sysClassNet, name), []byte("bond0 bond1\n"), 0o644); err != nil {
+		f.t.Fatal(err)
+	}
+}
+
 func TestSelect(t *testing.T) {
 	tests := []struct {
 		name       string
@@ -97,6 +106,7 @@ func TestSelect(t *testing.T) {
 				f.physical(testNIC2, "ice")
 				f.virtual("lo")
 				f.virtual("bond0")
+				f.file("bonding_masters")
 			},
 			required: []string{testNIC1, testNIC2},
 			want:     Native,
@@ -107,6 +117,7 @@ func TestSelect(t *testing.T) {
 				f.physical("ens1f0np0", "bnxt_en")
 				f.physical("ens3f0np0", "bnxt_en")
 				f.virtual("bond1")
+				f.file("bonding_masters")
 			},
 			required:   []string{"ens1f0np0", "ens3f0np0"},
 			want:       Generic,