Support cli uninstall (#3399)

* Add uninstall cmd
- init fn to uninstall velero
- abstract dynamic client creation to a separate fn
- creates a separate client per unstructured resource
- add delete client for CRDs
- export appendUnstructured
- add uninstall command to main cmd
- export `podTemplateOption`
- uninstall resources in the reverse order of installation
- fallback to `velero` if no ns is provided during uninstall
- skip deletion if the resource doesn't exist
- handle resource not found error
- match log formatting with cli install logs
- add Delete fn to fake client
- fix import order
- add changelog
- add comment doc for CreateClient fn

Signed-off-by: Suraj Banakar <suraj@infracloud.io>

* Re-use uninstall code from test suite
- move helper functions out of test suite
- this is to prevent cyclic imports
- move uninstall helpers to uninstall cmd
- call them from test suite
- revert export of variables/fns from install code
- because not required anymore

Signed-off-by: Suraj Banakar <suraj@infracloud.io>

* Revert `PodTemplateOption` -> `podTemplateOption`

Signed-off-by: Suraj Banakar <suraj@infracloud.io>

* Use uninstall helper under VeleroUninstall
- as a wrapper
- fix import related errors in test suite

Signed-off-by: Suraj Banakar <suraj@infracloud.io>

pkg/cmd/cli/uninstall/uninstall.go

@@ -0,0 +1,114 @@
+/*
+Copyright the Velero contributors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package uninstall
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/kubernetes"
+
+	apiextensionsclientset "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset"
+
+	"github.com/vmware-tanzu/velero/pkg/client"
+	"github.com/vmware-tanzu/velero/pkg/cmd"
+	"github.com/vmware-tanzu/velero/pkg/cmd/util/output"
+	"github.com/vmware-tanzu/velero/pkg/install"
+	"github.com/vmware-tanzu/velero/pkg/util/kube"
+)
+
+// Uninstall uninstalls all components deployed using velero install command
+func Uninstall(ctx context.Context, client *kubernetes.Clientset, extensionsClient *apiextensionsclientset.Clientset, veleroNamespace string) error {
+	if veleroNamespace == "" {
+		veleroNamespace = "velero"
+	}
+	err := DeleteNamespace(ctx, client, veleroNamespace)
+	if err != nil {
+		return errors.WithMessagef(err, "Uninstall failed removing Velero namespace %s", veleroNamespace)
+	}
+
+	rolebinding := install.ClusterRoleBinding(veleroNamespace)
+
+	err = client.RbacV1().ClusterRoleBindings().Delete(ctx, rolebinding.Name, metav1.DeleteOptions{})
+	if err != nil {
+		return errors.WithMessagef(err, "Uninstall failed removing Velero cluster role binding %s", rolebinding)
+	}
+	veleroLabels := labels.FormatLabels(install.Labels())
+
+	crds, err := extensionsClient.ApiextensionsV1().CustomResourceDefinitions().List(ctx, metav1.ListOptions{
+		LabelSelector: veleroLabels,
+	})
+	if err != nil {
+		return errors.WithMessagef(err, "Uninstall failed listing Velero crds")
+	}
+	for _, removeCRD := range crds.Items {
+		err = extensionsClient.ApiextensionsV1().CustomResourceDefinitions().Delete(ctx, removeCRD.ObjectMeta.Name, metav1.DeleteOptions{})
+		if err != nil {
+			return errors.WithMessagef(err, "Uninstall failed removing CRD %s", removeCRD.ObjectMeta.Name)
+		}
+	}
+
+	fmt.Println("Uninstalled Velero")
+	return nil
+}
+
+func DeleteNamespace(ctx context.Context, client *kubernetes.Clientset, namespace string) error {
+	err := client.CoreV1().Namespaces().Delete(ctx, namespace, metav1.DeleteOptions{})
+	if err != nil {
+		return errors.WithMessagef(err, "Delete namespace failed removing namespace %s", namespace)
+	}
+	return wait.Poll(1*time.Second, 3*time.Minute, func() (bool, error) {
+		_, err := client.CoreV1().Namespaces().Get(ctx, namespace, metav1.GetOptions{})
+		if err != nil {
+			// Commented this out because not sure if removing this is okay
+			// Printing this on Uninstall will lead to confusion
+			// fmt.Printf("Namespaces.Get after delete return err %v\n", err)
+			return true, nil // Assume any error means the delete was successful
+		}
+		return false, nil
+	})
+}
+
+// NewCommand creates a cobra command.
+func NewCommand(f client.Factory) *cobra.Command {
+	c := &cobra.Command{
+		Use:   "uninstall",
+		Short: "Uninstall Velero",
+		Long: `Uninstall Velero along with the CRDs.
+
+The '--namespace' flag can be used to specify the namespace where velero is installed (default: velero).
+		`,
+		Example: `# velero uninstall -n backup`,
+		Run: func(c *cobra.Command, args []string) {
+			veleroNs := strings.TrimSpace(f.Namespace())
+			cl, extCl, err := kube.GetClusterClient()
+			cmd.CheckError(err)
+			cmd.CheckError(Uninstall(context.Background(), cl, extCl, veleroNs))
+		},
+	}
+
+	output.BindFlags(c.Flags())
+	output.ClearOutputFlagDefault(c)
+	return c
+}