Add delete, export, get image-update

This uses the established abstractions to implement the usual
subcommands for the ImageUpdateAutomation type.

I've called the sub-subcommand in each case `image-update`, as a
fairly safe shorthand for the much longer `image-update-automation`.

Signed-off-by: Michael Bridgen <michael@weave.works>

cmd/flux/export_auto_imageupdateauto.go

@@ -0,0 +1,93 @@
+/*
+Copyright 2020 The Flux authors
+
+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 main
+
+import (
+	"github.com/spf13/cobra"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+
+	autov1 "github.com/fluxcd/image-automation-controller/api/v1alpha1"
+)
+
+var exportImageUpdateCmd = &cobra.Command{
+	Use:   "image-update [name]",
+	Short: "Export ImageUpdateAutomation resources in YAML format",
+	Long:  "The export image-update command exports one or all ImageUpdateAutomation resources in YAML format.",
+	Example: `  # Export all ImageUpdateAutomation resources
+  flux export auto image-update --all > updates.yaml
+
+  # Export a specific automation
+  flux export auto image-update latest-images > latest.yaml
+`,
+	RunE: exportCommand{
+		object: exportableImageUpdate{&autov1.ImageUpdateAutomation{}},
+		list:   exportableImageUpdateList{&autov1.ImageUpdateAutomationList{}},
+	}.run,
+}
+
+func init() {
+	exportAutoCmd.AddCommand(exportImageUpdateCmd)
+}
+
+// exportImageUpdate returns a value which has extraneous information
+// stripped out.
+func exportImageUpdate(item *autov1.ImageUpdateAutomation) interface{} {
+	gvk := autov1.GroupVersion.WithKind(autov1.ImageUpdateAutomationKind)
+	export := autov1.ImageUpdateAutomation{
+		TypeMeta: metav1.TypeMeta{
+			Kind:       gvk.Kind,
+			APIVersion: gvk.GroupVersion().String(),
+		},
+		ObjectMeta: metav1.ObjectMeta{
+			Name:        item.Name,
+			Namespace:   item.Namespace,
+			Labels:      item.Labels,
+			Annotations: item.Annotations,
+		},
+		Spec: item.Spec,
+	}
+	return export
+}
+
+type exportableImageUpdate struct {
+	update *autov1.ImageUpdateAutomation
+}
+
+func (ex exportableImageUpdate) AsClientObject() runtime.Object {
+	return ex.update
+}
+
+func (ex exportableImageUpdate) Export() interface{} {
+	return exportImageUpdate(ex.update)
+}
+
+type exportableImageUpdateList struct {
+	list *autov1.ImageUpdateAutomationList
+}
+
+func (ex exportableImageUpdateList) AsClientObject() runtime.Object {
+	return ex.list
+}
+
+func (ex exportableImageUpdateList) Len() int {
+	return len(ex.list.Items)
+}
+
+func (ex exportableImageUpdateList) ExportAt(i int) interface{} {
+	return exportImageUpdate(&ex.list.Items[i])
+}