rollout undo add dry-run implementation

hack/make-rules/test-cmd.sh

@@ -1931,6 +1931,9 @@ __EOF__
   # Update the deployment (revision 2)
   kubectl apply -f hack/testdata/deployment-revision2.yaml "${kube_flags[@]}"
   kube::test::get_object_assert deployment.extensions "{{range.items}}{{$deployment_image_field}}:{{end}}" "${IMAGE_DEPLOYMENT_R2}:"
+  # Rollback to revision 1 with dry-run - should be no-op
+  kubectl rollout undo deployment nginx --to-revision=1 --dry-run=true "${kube_flags[@]}"
+  kube::test::get_object_assert deployment.extensions "{{range.items}}{{$deployment_image_field}}:{{end}}" "${IMAGE_DEPLOYMENT_R2}:"
   # Rollback to revision 1
   kubectl rollout undo deployment nginx --to-revision=1 "${kube_flags[@]}"
   sleep 1

pkg/kubectl/cmd/rollout/rollout_undo.go

@@ -38,6 +38,7 @@ type UndoOptions struct {
 	Typer       runtime.ObjectTyper
 	Infos       []*resource.Info
 	ToRevision  int64
+	DryRun      bool
 
 	Out       io.Writer
 	Filenames []string
@@ -52,7 +53,10 @@ var (
 		kubectl rollout undo deployment/abc
 
 		# Rollback to deployment revision 3
-		kubectl rollout undo deployment/abc --to-revision=3`)
+		kubectl rollout undo deployment/abc --to-revision=3
+
+		# Rollback to the previous deployment with dry-run
+		kubectl rollout undo --dry-run=true deployment/abc`)
 )
 
 func NewCmdRolloutUndo(f *cmdutil.Factory, out io.Writer) *cobra.Command {
@@ -80,6 +84,7 @@ func NewCmdRolloutUndo(f *cmdutil.Factory, out io.Writer) *cobra.Command {
 	cmd.Flags().Int64("to-revision", 0, "The revision to rollback to. Default to 0 (last revision).")
 	usage := "Filename, directory, or URL to a file identifying the resource to get from a server."
 	kubectl.AddJsonFilenameFlag(cmd, &opts.Filenames, usage)
+	cmdutil.AddDryRunFlag(cmd)
 	cmdutil.AddRecursiveFlag(cmd, &opts.Recursive)
 	return cmd
 }
@@ -92,6 +97,7 @@ func (o *UndoOptions) CompleteUndo(f *cmdutil.Factory, cmd *cobra.Command, out i
 	o.ToRevision = cmdutil.GetFlagInt64(cmd, "to-revision")
 	o.Mapper, o.Typer = f.Object(false)
 	o.Out = out
+	o.DryRun = cmdutil.GetFlagBool(cmd, "dry-run")
 
 	cmdNamespace, enforceNamespace, err := f.DefaultNamespace()
 	if err != nil {
@@ -129,7 +135,7 @@ func (o *UndoOptions) CompleteUndo(f *cmdutil.Factory, cmd *cobra.Command, out i
 func (o *UndoOptions) RunUndo() error {
 	allErrs := []error{}
 	for ix, info := range o.Infos {
-		result, err := o.Rollbackers[ix].Rollback(info.Object, nil, o.ToRevision)
+		result, err := o.Rollbackers[ix].Rollback(info.Object, nil, o.ToRevision, o.DryRun)
 		if err != nil {
 			allErrs = append(allErrs, cmdutil.AddSourceToErr("undoing", info.Source, err))
 			continue

pkg/kubectl/cmd/util/factory.go

@@ -631,10 +631,10 @@ func NewFactory(optionalClientConfig clientcmd.ClientConfig) *Factory {
 		HistoryViewer: func(mapping *meta.RESTMapping) (kubectl.HistoryViewer, error) {
 			mappingVersion := mapping.GroupVersionKind.GroupVersion()
 			client, err := clients.ClientForVersion(&mappingVersion)
-			clientset := clientset.FromUnversionedClient(client)
 			if err != nil {
 				return nil, err
 			}
+			clientset := clientset.FromUnversionedClient(client)
 			return kubectl.HistoryViewerFor(mapping.GroupVersionKind.GroupKind(), clientset)
 		},
 		Rollbacker: func(mapping *meta.RESTMapping) (kubectl.Rollbacker, error) {
@@ -643,7 +643,8 @@ func NewFactory(optionalClientConfig clientcmd.ClientConfig) *Factory {
 			if err != nil {
 				return nil, err
 			}
-			return kubectl.RollbackerFor(mapping.GroupVersionKind.GroupKind(), client)
+			clientset := clientset.FromUnversionedClient(client)
+			return kubectl.RollbackerFor(mapping.GroupVersionKind.GroupKind(), clientset)
 		},
 		StatusViewer: func(mapping *meta.RESTMapping) (kubectl.StatusViewer, error) {
 			mappingVersion := mapping.GroupVersionKind.GroupVersion()

pkg/kubectl/rollback.go

@@ -17,6 +17,7 @@ limitations under the License.
 package kubectl
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"os/signal"
@@ -25,18 +26,19 @@ import (
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/apis/extensions"
-	client "k8s.io/kubernetes/pkg/client/unversioned"
+	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
 	deploymentutil "k8s.io/kubernetes/pkg/controller/deployment/util"
 	"k8s.io/kubernetes/pkg/runtime"
+	sliceutil "k8s.io/kubernetes/pkg/util/slice"
 	"k8s.io/kubernetes/pkg/watch"
 )
 
 // Rollbacker provides an interface for resources that can be rolled back.
 type Rollbacker interface {
-	Rollback(obj runtime.Object, updatedAnnotations map[string]string, toRevision int64) (string, error)
+	Rollback(obj runtime.Object, updatedAnnotations map[string]string, toRevision int64, dryRun bool) (string, error)
 }
 
-func RollbackerFor(kind unversioned.GroupKind, c client.Interface) (Rollbacker, error) {
+func RollbackerFor(kind unversioned.GroupKind, c clientset.Interface) (Rollbacker, error) {
 	switch kind {
 	case extensions.Kind("Deployment"):
 		return &DeploymentRollbacker{c}, nil
@@ -45,14 +47,17 @@ func RollbackerFor(kind unversioned.GroupKind, c client.Interface) (Rollbacker,
 }
 
 type DeploymentRollbacker struct {
-	c client.Interface
+	c clientset.Interface
 }
 
-func (r *DeploymentRollbacker) Rollback(obj runtime.Object, updatedAnnotations map[string]string, toRevision int64) (string, error) {
+func (r *DeploymentRollbacker) Rollback(obj runtime.Object, updatedAnnotations map[string]string, toRevision int64, dryRun bool) (string, error) {
 	d, ok := obj.(*extensions.Deployment)
 	if !ok {
 		return "", fmt.Errorf("passed object is not a Deployment: %#v", obj)
 	}
+	if dryRun {
+		return simpleDryRun(d, r.c, toRevision)
+	}
 	if d.Spec.Paused {
 		return "", fmt.Errorf("you cannot rollback a paused deployment; resume it first with 'kubectl rollout resume deployment/%s' and try again", d.Name)
 	}
@@ -66,7 +71,7 @@ func (r *DeploymentRollbacker) Rollback(obj runtime.Object, updatedAnnotations m
 	result := ""
 
 	// Get current events
-	events, err := r.c.Events(d.Namespace).List(api.ListOptions{})
+	events, err := r.c.Core().Events(d.Namespace).List(api.ListOptions{})
 	if err != nil {
 		return result, err
 	}
@@ -75,7 +80,7 @@ func (r *DeploymentRollbacker) Rollback(obj runtime.Object, updatedAnnotations m
 		return result, err
 	}
 	// Watch for the changes of events
-	watch, err := r.c.Events(d.Namespace).Watch(api.ListOptions{Watch: true, ResourceVersion: events.ResourceVersion})
+	watch, err := r.c.Core().Events(d.Namespace).Watch(api.ListOptions{Watch: true, ResourceVersion: events.ResourceVersion})
 	if err != nil {
 		return result, err
 	}
@@ -123,3 +128,50 @@ func isRollbackEvent(e *api.Event) (bool, string) {
 	}
 	return false, ""
 }
+
+func simpleDryRun(deployment *extensions.Deployment, c clientset.Interface, toRevision int64) (string, error) {
+	_, allOldRSs, newRS, err := deploymentutil.GetAllReplicaSets(deployment, c)
+	if err != nil {
+		return "", fmt.Errorf("failed to retrieve replica sets from deployment %s: %v", deployment.Name, err)
+	}
+	allRSs := allOldRSs
+	if newRS != nil {
+		allRSs = append(allRSs, newRS)
+	}
+
+	revisionToSpec := make(map[int64]*api.PodTemplateSpec)
+	for _, rs := range allRSs {
+		v, err := deploymentutil.Revision(rs)
+		if err != nil {
+			continue
+		}
+		revisionToSpec[v] = &rs.Spec.Template
+	}
+
+	if len(revisionToSpec) == 0 {
+		return "No rollout history found.", nil
+	}
+
+	if toRevision > 0 {
+		template, ok := revisionToSpec[toRevision]
+		if !ok {
+			return "", fmt.Errorf("unable to find specified revision")
+		}
+		buf := bytes.NewBuffer([]byte{})
+		DescribePodTemplate(template, buf)
+		return buf.String(), nil
+	}
+
+	// Sort the revisionToSpec map by revision
+	revisions := make([]int64, 0, len(revisionToSpec))
+	for r := range revisionToSpec {
+		revisions = append(revisions, r)
+	}
+	sliceutil.SortInts64(revisions)
+
+	template, _ := revisionToSpec[revisions[len(revisions)-1]]
+	buf := bytes.NewBuffer([]byte{})
+	buf.WriteString("\n")
+	DescribePodTemplate(template, buf)
+	return buf.String(), nil
+}