Restructure the Apply command to separate printing from the code that actually does the work

cmd/kubectl/kubectlcobra/basic_printer.go

@@ -0,0 +1,62 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package kubectlcobra
+
+import (
+	"fmt"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+	cmdutil "k8s.io/kubectl/pkg/cmd/util"
+	"sigs.k8s.io/kustomize/kstatus/wait"
+)
+
+// BasicPrinter is a simple implementation that just prints the events
+// from the channel in the default format for kubectl.
+// We need to support different printers for different output formats.
+type BasicPrinter struct {
+	ioStreams genericclioptions.IOStreams
+}
+
+// Print outputs the events from the provided channel in a simple
+// format on StdOut. As we support other printer implementations
+// this should probably be an interface.
+// This function will block until the channel is closed.
+func (b *BasicPrinter) Print(ch <-chan Event) {
+	for event := range ch {
+		switch event.EventType {
+		case ErrorEventType:
+			cmdutil.CheckErr(event.ErrorEvent.Err)
+		case ApplyEventType:
+			obj := event.ApplyEvent.Object
+			gvk := obj.GetObjectKind().GroupVersionKind()
+			name := "<unknown>"
+			if acc, err := meta.Accessor(obj); err == nil {
+				if n := acc.GetName(); len(n) > 0 {
+					name = n
+				}
+			}
+			fmt.Fprintf(b.ioStreams.Out, "%s %s\n", resourceIdToString(gvk.GroupKind(), name), event.ApplyEvent.Operation)
+		case StatusEventType:
+			statusEvent := event.StatusEvent
+			switch statusEvent.Type {
+			case wait.ResourceUpdate:
+				id := statusEvent.EventResource.ResourceIdentifier
+				gk := id.GroupKind
+				fmt.Fprintf(b.ioStreams.Out, "%s is %s: %s\n", resourceIdToString(gk, id.Name), statusEvent.EventResource.Status.String(), statusEvent.EventResource.Message)
+			case wait.Completed:
+				fmt.Fprint(b.ioStreams.Out, "all resources has reached the Current status\n")
+			case wait.Aborted:
+				fmt.Fprintf(b.ioStreams.Out, "resources failed to the reached Current status\n")
+			}
+		}
+	}
+}
+
+// resourceIdToString returns the string representation of a GroupKind and a resource name.
+func resourceIdToString(gk schema.GroupKind, name string) string {
+	return fmt.Sprintf("%s/%s", strings.ToLower(gk.String()), name)
+}