Add GetKernelVersion to ipvs.KernelHandler interface

ipvs `getProxyMode` test fails on mac as `utilipvs.GetRequiredIPVSMods`
try to reach `/proc/sys/kernel/osrelease` to find version of the running
linux kernel. Linux kernel version is used to determine the list of required
kernel modules for ipvs.

Logic to determine kernel version is moved to GetKernelVersion
method in LinuxKernelHandler which implements ipvs.KernelHandler.
Mock KernelHandler is used in the test cases.

Read and parse file is converted to go function instead of execing cut.

pkg/proxy/ipvs/proxier_test.go

@@ -24,15 +24,12 @@ import (
 	"strings"
 	"testing"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/intstr"
-	"k8s.io/kubernetes/pkg/proxy"
-	"k8s.io/utils/exec"
-	fakeexec "k8s.io/utils/exec/testing"
-
 	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/kubernetes/pkg/proxy"
 	netlinktest "k8s.io/kubernetes/pkg/proxy/ipvs/testing"
 	utilproxy "k8s.io/kubernetes/pkg/proxy/util"
 	proxyutiltest "k8s.io/kubernetes/pkg/proxy/util/testing"
@@ -42,6 +39,8 @@ import (
 	iptablestest "k8s.io/kubernetes/pkg/util/iptables/testing"
 	utilipvs "k8s.io/kubernetes/pkg/util/ipvs"
 	ipvstest "k8s.io/kubernetes/pkg/util/ipvs/testing"
+	"k8s.io/utils/exec"
+	fakeexec "k8s.io/utils/exec/testing"
 )
 
 const testHostname = "test-hostname"
@@ -90,13 +89,18 @@ func (fake *fakeHealthChecker) SyncEndpoints(newEndpoints map[types.NamespacedNa
 
 // fakeKernelHandler implements KernelHandler.
 type fakeKernelHandler struct {
-	modules []string
+	modules       []string
+	kernelVersion string
 }
 
 func (fake *fakeKernelHandler) GetModules() ([]string, error) {
 	return fake.modules, nil
 }
 
+func (fake *fakeKernelHandler) GetKernelVersion() (string, error) {
+	return fake.kernelVersion, nil
+}
+
 // fakeKernelHandler implements KernelHandler.
 type fakeIPSetVersioner struct {
 	version string
@@ -256,64 +260,79 @@ func TestCleanupLeftovers(t *testing.T) {
 
 func TestCanUseIPVSProxier(t *testing.T) {
 	testCases := []struct {
-		mods         []string
-		kernelErr    error
-		ipsetVersion string
-		ipsetErr     error
-		ok           bool
+		mods          []string
+		kernelVersion string
+		kernelErr     error
+		ipsetVersion  string
+		ipsetErr      error
+		ok            bool
 	}{
 		// case 0, kernel error
 		{
-			mods:         []string{"foo", "bar", "baz"},
-			kernelErr:    fmt.Errorf("oops"),
-			ipsetVersion: "0.0",
-			ok:           false,
+			mods:          []string{"foo", "bar", "baz"},
+			kernelVersion: "4.19",
+			kernelErr:     fmt.Errorf("oops"),
+			ipsetVersion:  "0.0",
+			ok:            false,
 		},
 		// case 1, ipset error
 		{
-			mods:         []string{"foo", "bar", "baz"},
-			ipsetVersion: MinIPSetCheckVersion,
-			ipsetErr:     fmt.Errorf("oops"),
-			ok:           false,
+			mods:          []string{"foo", "bar", "baz"},
+			kernelVersion: "4.19",
+			ipsetVersion:  MinIPSetCheckVersion,
+			ipsetErr:      fmt.Errorf("oops"),
+			ok:            false,
 		},
 		// case 2, missing required kernel modules and ipset version too low
 		{
-			mods:         []string{"foo", "bar", "baz"},
-			ipsetVersion: "1.1",
-			ok:           false,
+			mods:          []string{"foo", "bar", "baz"},
+			kernelVersion: "4.19",
+			ipsetVersion:  "1.1",
+			ok:            false,
 		},
 		// case 3, missing required ip_vs_* kernel modules
 		{
-			mods:         []string{"ip_vs", "a", "bc", "def"},
-			ipsetVersion: MinIPSetCheckVersion,
-			ok:           false,
+			mods:          []string{"ip_vs", "a", "bc", "def"},
+			kernelVersion: "4.19",
+			ipsetVersion:  MinIPSetCheckVersion,
+			ok:            false,
 		},
 		// case 4, ipset version too low
 		{
-			mods:         []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack_ipv4"},
-			ipsetVersion: "4.3.0",
-			ok:           false,
+			mods:          []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack"},
+			kernelVersion: "4.19",
+			ipsetVersion:  "4.3.0",
+			ok:            false,
 		},
-		// case 5
+		// case 5, ok for linux kernel 4.19
 		{
-			mods:         []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack_ipv4"},
-			ipsetVersion: MinIPSetCheckVersion,
-			ok:           true,
+			mods:          []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack"},
+			kernelVersion: "4.19",
+			ipsetVersion:  MinIPSetCheckVersion,
+			ok:            true,
 		},
-		// case 6
+		// case 6, ok for linux kernel 4.18
 		{
-			mods:         []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack_ipv4", "foo", "bar"},
-			ipsetVersion: "6.19",
-			ok:           true,
+			mods:          []string{"ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack_ipv4"},
+			kernelVersion: "4.18",
+			ipsetVersion:  MinIPSetCheckVersion,
+			ok:            true,
+		},
+		// case 7. ok when module list has extra modules
+		{
+			mods:          []string{"foo", "ip_vs", "ip_vs_rr", "ip_vs_wrr", "ip_vs_sh", "nf_conntrack", "bar"},
+			kernelVersion: "4.19",
+			ipsetVersion:  "6.19",
+			ok:            true,
 		},
 	}
 
 	for i := range testCases {
-		handle := &fakeKernelHandler{modules: testCases[i].mods}
+		handle := &fakeKernelHandler{modules: testCases[i].mods, kernelVersion: testCases[i].kernelVersion}
 		versioner := &fakeIPSetVersioner{version: testCases[i].ipsetVersion, err: testCases[i].ipsetErr}
-		ok, _ := CanUseIPVSProxier(handle, versioner)
+		ok, err := CanUseIPVSProxier(handle, versioner)
 		if ok != testCases[i].ok {
-			t.Errorf("Case [%d], expect %v, got %v", i, testCases[i].ok, ok)
+			t.Errorf("Case [%d], expect %v, got %v: err: %v", i, testCases[i].ok, ok, err)
 		}
 	}
 }
@@ -3140,3 +3159,33 @@ func TestMultiPortServiceBindAddr(t *testing.T) {
 		t.Errorf("Expected number of remaining bound addrs after cleanup to be %v. Got %v", 0, len(remainingAddrs))
 	}
 }
+
+func Test_getFirstColumn(t *testing.T) {
+	testCases := []struct {
+		name        string
+		fileContent string
+		want        []string
+		wantErr     bool
+	}{
+		{
+			name: "valid content",
+			fileContent: `libiscsi_tcp 28672 1 iscsi_tcp, Live 0xffffffffc07ae000
+libiscsi 57344 3 ib_iser,iscsi_tcp,libiscsi_tcp, Live 0xffffffffc079a000
+raid10 57344 0 - Live 0xffffffffc0597000`,
+			want:    []string{"libiscsi_tcp", "libiscsi", "raid10"},
+			wantErr: false,
+		},
+	}
+	for _, test := range testCases {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := getFirstColumn(strings.NewReader(test.fileContent))
+			if (err != nil) != test.wantErr {
+				t.Errorf("getFirstColumn() error = %v, wantErr %v", err, test.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("getFirstColumn() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}