fix: improve liqoctl uninstall error message

this patch improves the liqoctl uninstall error message when the
pre-uninstall checks fail, by suggesting the user which command has to
be used to unpeer a cluster.

pkg/liqoctl/uninstall/handler.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"slices"
 	"strings"
 	"time"
 
@@ -67,6 +68,25 @@ func (o *Options) Run(ctx context.Context) error {
 	s := o.Printer.StartSpinner("Running pre-uninstall checks")
 	if err := utils.PreUninstall(ctx, o.CRClient); err != nil {
 		s.Fail("Pre-uninstall checks failed: ", output.PrettyErr(err))
+		var uninstallErr utils.UninstallError
+		if errors.As(err, &uninstallErr) {
+			errorTypes := uninstallErr.GetErrorTypes()
+			if slices.Contains(errorTypes, utils.PendingActivePeerings) {
+				o.Printer.Error.Printfln(
+					"You must remove all the active peerings with other clusters before uninstalling Liqo.\n" +
+						"You can disable the active peerings via the 'liqoctl unpeer' command.\n" +
+						"Check 'liqoctl unpeer --help' for further information.",
+				)
+			}
+
+			if slices.Contains(errorTypes, utils.PendingOffloadedNamespaces) {
+				o.Printer.Error.Printfln(
+					"You must remove all the offloaded namespaces before uninstalling Liqo.\n" +
+						"You can disable the namespace offloading 'liqoctl unoffload' command.\n" +
+						"Check 'liqoctl unoffload --help' for further information.\n",
+				)
+			}
+		}
 		return err
 	}
 	s.Success("Pre-uninstall checks passed")

pkg/utils/preuninstall.go

@@ -17,6 +17,7 @@ package utils
 import (
 	"context"
 	"fmt"
+	"maps"
 	"slices"
 
 	"sigs.k8s.io/controller-runtime/pkg/client"
@@ -32,6 +33,18 @@ import (
 	ipamutils "github.com/liqotech/liqo/pkg/utils/ipam"
 )
 
+// UninstallErrorType is the type of uninstall error.
+type UninstallErrorType string
+
+const (
+	// GenericUninstallError is an error related to resources that needs to be removed.
+	GenericUninstallError = "generic"
+	// PendingActivePeerings is an error related peerings still active.
+	PendingActivePeerings = "pendingActivePeerings"
+	// PendingOffloadedNamespaces is an error related to namespaces still offloaded.
+	PendingOffloadedNamespaces = "pendingOffloadedNamespaces"
+)
+
 type errorMap struct {
 	networking     []string
 	authentication []string
@@ -50,53 +63,74 @@ func newErrorMap() errorMap {
 	}
 }
 
+// UninstallError is an error type returned when there are errors during the uninstall process.
+type UninstallError struct {
+	errorTypes []UninstallErrorType
+	message    string
+}
+
+// GetErrorTypes returns the type of uninstall error.
+func (ue UninstallError) GetErrorTypes() []UninstallErrorType {
+	return ue.errorTypes
+}
+
+// Error returns the error message.
+func (ue UninstallError) Error() string {
+	return ue.message
+}
+
 func (em *errorMap) getError() error {
 	str := ""
-	hasErr := false
+	errorTypes := map[UninstallErrorType]bool{}
 
 	if len(em.networking) > 0 {
 		str += "\ndisable networking for clusters:\n"
 		for _, fc := range em.networking {
 			str += fmt.Sprintf("- %s\n", fc)
 		}
-		hasErr = true
+		errorTypes[PendingActivePeerings] = true
 	}
 
 	if len(em.authentication) > 0 {
 		str += "\ndisable authentication for clusters:\n"
 		for i := range em.authentication {
 			str += fmt.Sprintf("- %s\n", em.authentication[i])
 		}
-		hasErr = true
+		errorTypes[PendingActivePeerings] = true
 	}
 
 	if len(em.offloading) > 0 {
 		str += "\ndisable offloading for clusters:\n"
 		for _, fc := range em.offloading {
 			str += fmt.Sprintf("- %s\n", fc)
 		}
-		hasErr = true
+		errorTypes[PendingActivePeerings] = true
 	}
 
 	if len(em.namespaces) > 0 {
 		str += "\nunoffload the following namespaces:\n"
 		for i := range em.namespaces {
 			str += fmt.Sprintf("- %s\n", em.namespaces[i])
 		}
-		hasErr = true
+		errorTypes[PendingOffloadedNamespaces] = true
 	}
 
 	if len(em.generic) > 0 {
 		str += "\nremove the following resources:\n"
 		for i := range em.generic {
 			str += fmt.Sprintf("- %s\n", em.generic[i])
 		}
-		hasErr = true
+		errorTypes[GenericUninstallError] = true
 	}
 
-	if hasErr {
-		return fmt.Errorf("you should:\n%s", str)
+	if len(errorTypes) > 0 {
+		msg := fmt.Sprintf("you should:\n%s", str)
+		return UninstallError{
+			errorTypes: slices.Collect(maps.Keys(errorTypes)),
+			message:    msg,
+		}
 	}
+
 	return nil
 }