Kubectl: check version skew (#127365)

Signed-off-by: Omer Aplatony <omerap12@gmail.com>

Kubernetes-commit: 35307319740a3a52cf4632c24b7f99d675537bdf

pkg/cmd/version/skew_warning.go

@@ -18,10 +18,10 @@ package version
 
 import (
 	"fmt"
-	"io"
+	"math"
+
 	"k8s.io/apimachinery/pkg/util/version"
 	apimachineryversion "k8s.io/apimachinery/pkg/version"
-	"math"
 )
 
 // supportedMinorVersionSkew is the maximum supported difference between the client and server minor versions.
@@ -29,26 +29,26 @@ import (
 // and server versions 1.18, 1.19, and 1.20 would be within the supported version skew for client version 1.19.
 const supportedMinorVersionSkew = 1
 
-// printVersionSkewWarning prints a warning message if the difference between the client and version is greater than
+// getVersionSkewWarning returns a warning message if the difference between the client and version is greater than
 // the supported version skew.
-func printVersionSkewWarning(w io.Writer, clientVersion, serverVersion apimachineryversion.Info) error {
+func getVersionSkewWarning(clientVersion, serverVersion apimachineryversion.Info) (string, error) {
 	parsedClientVersion, err := version.ParseSemantic(clientVersion.GitVersion)
 	if err != nil {
-		return err
+		return "", fmt.Errorf("client version error: %w", err)
 	}
 
 	parsedServerVersion, err := version.ParseSemantic(serverVersion.GitVersion)
 	if err != nil {
-		return err
+		return "", fmt.Errorf("server version error: %w", err)
 	}
 
 	majorVersionDifference := math.Abs(float64(parsedClientVersion.Major()) - float64(parsedServerVersion.Major()))
 	minorVersionDifference := math.Abs(float64(parsedClientVersion.Minor()) - float64(parsedServerVersion.Minor()))
 
 	if majorVersionDifference > 0 || minorVersionDifference > supportedMinorVersionSkew {
-		fmt.Fprintf(w, "WARNING: version difference between client (%d.%d) and server (%d.%d) exceeds the supported minor version skew of +/-%d\n",
+		warningMessage := fmt.Sprintf("version difference between client (%d.%d) and server (%d.%d) exceeds the supported minor version skew of +/-%d",
 			parsedClientVersion.Major(), parsedClientVersion.Minor(), parsedServerVersion.Major(), parsedServerVersion.Minor(), supportedMinorVersionSkew)
+		return warningMessage, nil
 	}
-
-	return nil
+	return "", nil
 }

pkg/cmd/version/skew_warning_test.go

@@ -17,14 +17,12 @@ limitations under the License.
 package version
 
 import (
-	"bytes"
-	apimachineryversion "k8s.io/apimachinery/pkg/version"
 	"testing"
+
+	apimachineryversion "k8s.io/apimachinery/pkg/version"
 )
 
 func TestPrintVersionSkewWarning(t *testing.T) {
-	output := &bytes.Buffer{}
-
 	testCases := []struct {
 		name              string
 		clientVersion     apimachineryversion.Info
@@ -82,14 +80,15 @@ func TestPrintVersionSkewWarning(t *testing.T) {
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			output.Reset()
+			warningMessage, err := getVersionSkewWarning(tc.clientVersion, tc.serverVersion)
+			if err != nil {
+				t.Errorf("error: %s", err)
+			}
 
-			printVersionSkewWarning(output, tc.clientVersion, tc.serverVersion)
-
-			if tc.isWarningExpected && output.Len() == 0 {
-				t.Error("warning was expected, but not written to the output")
-			} else if !tc.isWarningExpected && output.Len() > 0 {
-				t.Errorf("warning was not expected, but was written to the output: %s", output.String())
+			if tc.isWarningExpected && warningMessage == "" {
+				t.Error("warning was expected")
+			} else if !tc.isWarningExpected && warningMessage != "" {
+				t.Errorf("warning was not expected. but got %s", warningMessage)
 			}
 		})
 	}

pkg/cmd/version/version.go

@@ -55,6 +55,7 @@ var (
 type Options struct {
 	ClientOnly       bool
 	Output           string
+	WarningsAsErrors bool
 
 	args []string
 
@@ -93,6 +94,9 @@ func NewCmdVersion(f cmdutil.Factory, ioStreams genericiooptions.IOStreams) *cob
 // Complete completes all the required options
 func (o *Options) Complete(f cmdutil.Factory, cmd *cobra.Command, args []string) error {
 	var err error
+
+	o.WarningsAsErrors = cmd.Flags().Lookup("warnings-as-errors").Value.String() == "true"
+
 	if o.ClientOnly {
 		return nil
 	}
@@ -162,11 +166,17 @@ func (o *Options) Run() error {
 	}
 
 	if versionInfo.ServerVersion != nil {
-		if err := printVersionSkewWarning(o.ErrOut, *versionInfo.ClientVersion, *versionInfo.ServerVersion); err != nil {
+		warningMessage, err := getVersionSkewWarning(*versionInfo.ClientVersion, *versionInfo.ServerVersion)
+		if err != nil {
 			return err
 		}
+		if warningMessage != "" {
+			if o.WarningsAsErrors {
+				return errors.New(warningMessage)
+			}
+			fmt.Fprintf(o.ErrOut, "Warning: %s\n", warningMessage) //nolint:errcheck
+		}
 	}
-
 	return serverErr
 }
 

pkg/cmd/version/version_test.go

@@ -20,8 +20,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/spf13/cobra"
-
 	"k8s.io/cli-runtime/pkg/genericiooptions"
 
 	cmdtesting "k8s.io/kubectl/pkg/cmd/testing"
@@ -32,13 +30,18 @@ func TestNewCmdVersionClientVersion(t *testing.T) {
 	defer tf.Cleanup()
 	streams, _, buf, _ := genericiooptions.NewTestIOStreams()
 	o := NewOptions(streams)
-	if err := o.Complete(tf, &cobra.Command{}, nil); err != nil {
+
+	cmd := NewCmdVersion(tf, streams)
+	cmd.Flags().Bool("warnings-as-errors", false, "")
+
+	if err := o.Complete(tf, cmd, nil); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 	if err := o.Validate(); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
-	if err := o.Complete(tf, &cobra.Command{}, []string{"extraParameter0"}); err != nil {
+
+	if err := o.Complete(tf, cmd, []string{"extraParameter0"}); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 	if err := o.Validate(); !strings.Contains(err.Error(), "extra arguments") {