Fix segfault when updating non-existent object

Fix #3935

cmd/kops/replace.go

@@ -23,12 +23,12 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
-	"k8s.io/kops/cmd/kops/util"
+	"k8s.io/apimachinery/pkg/api/errors"
-	"k8s.io/kops/util/pkg/vfs"
-
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/kops/cmd/kops/util"
 	kopsapi "k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/pkg/kopscodecs"
+	"k8s.io/kops/util/pkg/vfs"
 	"k8s.io/kubernetes/pkg/kubectl/cmd/templates"
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/kubectl/resource"
@@ -77,7 +77,7 @@ func NewCmdReplace(f *util.Factory, out io.Writer) *cobra.Command {
 		},
 	}
 	cmd.Flags().StringSliceVarP(&options.Filenames, "filename", "f", options.Filenames, "A list of one or more files separated by a comma.")
-	cmd.Flags().BoolVarP(&options.force, "force", "", false, "Force any changes, which will also create any non-existing respurce (defaults to instancegroups only)")
+	cmd.Flags().BoolVarP(&options.force, "force", "", false, "Force any changes, which will also create any non-existing resource")
 	cmd.MarkFlagRequired("filename")
 
 	return cmd
@@ -124,11 +124,31 @@ func RunReplace(f *util.Factory, cmd *cobra.Command, out io.Writer, c *replaceOp
 						return err
 					}
 
+					// Check if the cluster exists already
+					clusterName := v.Name
+					cluster, err := clientset.GetCluster(clusterName)
+					if err != nil {
+						if errors.IsNotFound(err) {
+							cluster = nil
+						} else {
+							return fmt.Errorf("error fetching cluster %q: %v", clusterName, err)
+						}
+					}
+					if cluster == nil {
+						if !c.force {
+							return fmt.Errorf("cluster %v does not exist (try adding --force flag)", clusterName)
+						}
+						_, err = clientset.CreateCluster(v)
+						if err != nil {
+							return fmt.Errorf("error creating cluster: %v", err)
+						}
+					} else {
 						_, err = clientset.UpdateCluster(v, status)
 						if err != nil {
 							return fmt.Errorf("error replacing cluster: %v", err)
 						}
 					}
+				}
 
 			case *kopsapi.InstanceGroup:
 				clusterName := v.ObjectMeta.Labels[kopsapi.LabelClusterName]
@@ -137,8 +157,12 @@ func RunReplace(f *util.Factory, cmd *cobra.Command, out io.Writer, c *replaceOp
 				}
 				cluster, err := clientset.GetCluster(clusterName)
 				if err != nil {
+					if errors.IsNotFound(err) {
+						cluster = nil
+					} else {
 						return fmt.Errorf("error fetching cluster %q: %v", clusterName, err)
 					}
+				}
 				if cluster == nil {
 					return fmt.Errorf("cluster %q not found", clusterName)
 				}

docs/cli/kops_replace.md

@@ -28,7 +28,7 @@ kops replace -f FILENAME
 
 ```
   -f, --filename stringSlice   A list of one or more files separated by a comma.
-      --force                  Force any changes, which will also create any non-existing respurce (defaults to instancegroups only)
+      --force                  Force any changes, which will also create any non-existing resource
 ```
 
 ### Options inherited from parent commands

pkg/client/simple/vfsclientset/cluster.go

@@ -23,7 +23,9 @@ import (
 	"time"
 
 	"github.com/golang/glog"
+	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apimachinery/pkg/watch"
@@ -50,6 +52,7 @@ func (c *ClusterVFS) Get(name string, options metav1.GetOptions) (*api.Cluster,
 	if options.ResourceVersion != "" {
 		return nil, fmt.Errorf("ResourceVersion not supported in ClusterVFS::Get")
 	}
+	// TODO: Return not found
 	return c.find(name)
 }
 
@@ -123,6 +126,10 @@ func (r *ClusterVFS) Update(c *api.Cluster, status *api.ClusterStatus) (*api.Clu
 		return nil, err
 	}
 
+	if old == nil {
+		return nil, errors.NewNotFound(schema.GroupResource{Group: api.GroupName, Resource: "Cluster"}, clusterName)
+	}
+
 	if err := validation.ValidateClusterUpdate(c, status, old).ToAggregate(); err != nil {
 		return nil, err
 	}