Add support for legacy names in extension uninstall (#6226)

Because extension label values have been changed, an older install of an extension will fail to be uninstalled with a more recent CLI version. This is because the uninstall command checks the new label value which doesn't match older installs.

This small change fixes that by checking both -- the new, non-prefixed version and the old prefixed one. The bug should have a relatively small impact since there are only a few edge releases that contain the prefixed label value (an exception being stable-2.10.0 which used the prefixed version still).

Signed-off-by: Matei David <matei@buoyant.io>

cli/cmd/uninstall.go

@@ -82,7 +82,12 @@ This command provides all Kubernetes namespace-scoped and cluster-scoped resourc
 				}
 			}
 
-			err = pkgCmd.Uninstall(cmd.Context(), k8sAPI, k8s.ControllerNSLabel)
+			selector, err := pkgCmd.GetLabelSelector(k8s.ControllerNSLabel)
+			if err != nil {
+				return err
+			}
+
+			err = pkgCmd.Uninstall(cmd.Context(), k8sAPI, selector)
 			if err != nil {
 				fmt.Fprintln(os.Stderr, err)
 			}

jaeger/cmd/check.go

@@ -19,6 +19,10 @@ const (
 	// JaegerExtensionName is the name of jaeger extension
 	JaegerExtensionName = "jaeger"
 
+	// JaegerLegacyExtension is the name of the jaeger extension prior to
+	// stable-2.10.0 when the linkerd prefix was removed.
+	JaegerLegacyExtension = "linkerd-jaeger"
+
 	// linkerdJaegerExtensionCheck adds checks related to the jaeger extension
 	linkerdJaegerExtensionCheck healthcheck.CategoryID = "linkerd-jaeger"
 )

jaeger/cmd/uninstall.go

@@ -38,5 +38,10 @@ func uninstallRunE(ctx context.Context) error {
 		return err
 	}
 
-	return pkgCmd.Uninstall(ctx, k8sAPI, fmt.Sprintf("%s=%s", k8s.LinkerdExtensionLabel, JaegerExtensionName))
+	selector, err := pkgCmd.GetLabelSelector(k8s.LinkerdExtensionLabel, JaegerExtensionName, JaegerLegacyExtension)
+	if err != nil {
+		return err
+	}
+
+	return pkgCmd.Uninstall(ctx, k8sAPI, selector)
 }

multicluster/cmd/check.go

@@ -30,6 +30,10 @@ const (
 	// MulticlusterExtensionName is the name of the multicluster extension
 	MulticlusterExtensionName = "multicluster"
 
+	// MulticlusterLegacyExtension is the name of the multicluster extension
+	// prior to stable-2.10.0 when the linkerd prefix was removed.
+	MulticlusterLegacyExtension = "linkerd-multicluster"
+
 	// linkerdMulticlusterExtensionCheck adds checks related to the multicluster extension
 	linkerdMulticlusterExtensionCheck healthcheck.CategoryID = "linkerd-multicluster"
 

multicluster/cmd/uninstall.go

@@ -53,7 +53,12 @@ func newMulticlusterUninstallCommand() *cobra.Command {
 				return errors.New(strings.Join(err, "\n"))
 			}
 
-			err = pkgCmd.Uninstall(cmd.Context(), k8sAPI, fmt.Sprintf("%s=%s", k8s.LinkerdExtensionLabel, MulticlusterExtensionName))
+			selector, err := pkgCmd.GetLabelSelector(k8s.LinkerdExtensionLabel, MulticlusterExtensionName, MulticlusterLegacyExtension)
+			if err != nil {
+				return err
+			}
+
+			err = pkgCmd.Uninstall(cmd.Context(), k8sAPI, selector)
 			if err != nil {
 				fmt.Fprintln(os.Stderr, err)
 				os.Exit(1)

pkg/cmd/cmd.go

@@ -13,6 +13,8 @@ import (
 	"github.com/spf13/cobra"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/selection"
 	"k8s.io/client-go/tools/clientcmd"
 )
 
@@ -125,3 +127,22 @@ func ConfigureKubeContextFlagCompletion(cmd *cobra.Command, kubeconfigPath strin
 			return suggestions, cobra.ShellCompDirectiveDefault
 		})
 }
+
+// GetLabelSelector creates a label selector as a string based on a label key
+// whose value may be in the set provided as an argument to the function. If the
+// value set is empty then the selector will match resources where the label key
+// exists regardless of value.
+func GetLabelSelector(labelKey string, labelValues ...string) (string, error) {
+	selectionOp := selection.In
+	if len(labelValues) < 1 {
+		selectionOp = selection.Exists
+	}
+
+	labelRequirement, err := labels.NewRequirement(labelKey, selectionOp, labelValues)
+	if err != nil {
+		return "", err
+	}
+
+	selector := labels.NewSelector().Add(*labelRequirement)
+	return selector.String(), nil
+}

viz/cmd/uninstall.go

@@ -8,8 +8,6 @@ import (
 	pkgCmd "github.com/linkerd/linkerd2/pkg/cmd"
 	"github.com/linkerd/linkerd2/pkg/k8s"
 	"github.com/spf13/cobra"
-	"k8s.io/apimachinery/pkg/labels"
-	"k8s.io/apimachinery/pkg/selection"
 )
 
 func newCmdUninstall() *cobra.Command {
@@ -40,11 +38,10 @@ func uninstallRunE(ctx context.Context) error {
 		return err
 	}
 
-	extensionReq, err := labels.NewRequirement(k8s.LinkerdExtensionLabel, selection.In, []string{ExtensionName, LegacyExtensionName})
+	selector, err := pkgCmd.GetLabelSelector(k8s.LinkerdExtensionLabel, ExtensionName, LegacyExtensionName)
 	if err != nil {
 		return err
 	}
 
-	selector := labels.NewSelector().Add(*extensionReq)
+	return pkgCmd.Uninstall(ctx, k8sAPI, selector)
-	return pkgCmd.Uninstall(ctx, k8sAPI, selector.String())
 }