Merge pull request #103238 from seans3/cmd-headers-beta

kubectl command headers as default in beta

staging/src/k8s.io/kubectl/pkg/cmd/cmd.go

@@ -32,6 +32,7 @@ import (
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 	cliflag "k8s.io/component-base/cli/flag"
+	"k8s.io/klog/v2"
 	"k8s.io/kubectl/pkg/cmd/annotate"
 	"k8s.io/kubectl/pkg/cmd/apiresources"
 	"k8s.io/kubectl/pkg/cmd/apply"
@@ -401,14 +402,19 @@ func NewKubectlCommand(in io.Reader, out, err io.Writer) *cobra.Command {
 //   2) Adds CommandHeaderRoundTripper as a wrapper around the standard
 //      RoundTripper. CommandHeaderRoundTripper adds X-Headers then delegates
 //      to standard RoundTripper.
-// For alpha, these hooks are only updated if the KUBECTL_COMMAND_HEADERS
+// For beta, these hooks are updated unless the KUBECTL_COMMAND_HEADERS environment variable
-// environment variable is set.
+// is set, and the value of the env var is false (or zero).
 // See SIG CLI KEP 859 for more information:
 //   https://github.com/kubernetes/enhancements/tree/master/keps/sig-cli/859-kubectl-headers
 func addCmdHeaderHooks(cmds *cobra.Command, kubeConfigFlags *genericclioptions.ConfigFlags) {
-	if _, exists := os.LookupEnv(kubectlCmdHeaders); !exists {
+	// If the feature gate env var is set to "false", then do no add kubectl command headers.
-		return
+	if value, exists := os.LookupEnv(kubectlCmdHeaders); exists {
+		if value == "false" || value == "0" {
+			klog.V(5).Infoln("kubectl command headers turned off")
+			return
+		}
 	}
+	klog.V(5).Infoln("kubectl command headers turned on")
 	crt := &genericclioptions.CommandHeaderRoundTripper{}
 	existingPreRunE := cmds.PersistentPreRunE
 	// Add command parsing to the existing persistent pre-run function.

staging/src/k8s.io/kubectl/pkg/cmd/cmd_test.go

@@ -23,6 +23,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/spf13/cobra"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	cmdutil "k8s.io/kubectl/pkg/cmd/util"
 )
@@ -158,3 +159,50 @@ func (h *testPluginHandler) Execute(executablePath string, cmdArgs, env []string
 	h.withEnv = env
 	return nil
 }
+
+func TestKubectlCommandHeadersHooks(t *testing.T) {
+	tests := map[string]struct {
+		envVar    string
+		addsHooks bool
+	}{
+		"empty environment variable; hooks added": {
+			envVar:    "",
+			addsHooks: true,
+		},
+		"random env var value; hooks added": {
+			envVar:    "foo",
+			addsHooks: true,
+		},
+		"true env var value; hooks added": {
+			envVar:    "true",
+			addsHooks: true,
+		},
+		"false env var value; hooks NOT added": {
+			envVar:    "false",
+			addsHooks: false,
+		},
+		"zero env var value; hooks NOT added": {
+			envVar:    "0",
+			addsHooks: false,
+		},
+	}
+
+	for name, testCase := range tests {
+		t.Run(name, func(t *testing.T) {
+			cmds := &cobra.Command{}
+			kubeConfigFlags := genericclioptions.NewConfigFlags(true).WithDeprecatedPasswordFlag()
+			if kubeConfigFlags.WrapConfigFn != nil {
+				t.Fatal("expected initial nil WrapConfigFn")
+			}
+			os.Setenv(kubectlCmdHeaders, testCase.envVar)
+			addCmdHeaderHooks(cmds, kubeConfigFlags)
+			// Valdidate whether the hooks were added.
+			if testCase.addsHooks && kubeConfigFlags.WrapConfigFn == nil {
+				t.Error("after adding kubectl command header, expecting non-nil WrapConfigFn")
+			}
+			if !testCase.addsHooks && kubeConfigFlags.WrapConfigFn != nil {
+				t.Error("env var feature gate should have blocked setting WrapConfigFn")
+			}
+		})
+	}
+}