NO-JIRA: Env override NETWORKING_E2E_BOND_MTU

This commit introduces NETWORKING_E2E_BOND_MTU variable.
The test for creating "bond" interface can read it to override
the default value. The default value is used when .status.clusterNetworkMTU is undefined on the Network source "cluster" and it is automatically set by kernel.

The .status.clusterNetworkMTU might not be defined when using acustom CNI plugin such as Cilium.

Author: mgencur

test/extended/networking/bonds.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"os"
+	"strconv"
 	"strings"
 
 	g "github.com/onsi/ginkgo/v2"
@@ -36,15 +38,23 @@ var _ = g.Describe("[sig-network][Feature:bond]", func() {
 		)
 		o.Expect(err).NotTo(o.HaveOccurred(), "unable to create macvlan network-attachment-definition")
 
-		networkConfig, err := oc.AdminConfigClient().ConfigV1().Networks().Get(context.Background(), "cluster", metav1.GetOptions{})
-		o.Expect(err).NotTo(o.HaveOccurred(), "unable to get network config")
+		var mtu int
+		if mtuEnv := os.Getenv("NETWORKING_E2E_BOND_MTU"); mtuEnv != "" {
+			mtu, err = strconv.Atoi(mtuEnv)
+			o.Expect(err).NotTo(o.HaveOccurred())
+		} else {
+			networkConfig, err := oc.AdminConfigClient().ConfigV1().Networks().
+				Get(context.Background(), "cluster", metav1.GetOptions{})
+			o.Expect(err).NotTo(o.HaveOccurred(), "unable to get network config")
+			mtu = networkConfig.Status.ClusterNetworkMTU
+		}
 
 		err = createBondNAD(
 			oc.AdminConfig(),
 			namespace,
 			bondnad1,
 			"192.0.2.10/24",
-			networkConfig.Status.ClusterNetworkMTU,
+			mtu,
 			"net1",
 			"net2",
 		)
@@ -55,7 +65,7 @@ var _ = g.Describe("[sig-network][Feature:bond]", func() {
 			namespace,
 			bondnad2,
 			"192.0.2.11/24",
-			networkConfig.Status.ClusterNetworkMTU,
+			mtu,
 			"net1",
 			"net2",
 		)