From 13be899b422a1f68c38e3a9c9d88831db709a32d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arda=20G=C3=BC=C3=A7l=C3=BC?= <aguclu@redhat.com>
Date: Fri, 2 Dec 2022 16:00:22 +0300
Subject: [PATCH] kubectl scale: Use visitor only once

`kubectl scale` calls visitor two times. Second call fails when
the piped input is passed by returning an
`error: no objects passed to scale` error.

This PR uses the result of first visitor and fixes that piped
input problem. In addition to that, this PR also adds new
scale test to verify.
---
 .../src/k8s.io/kubectl/pkg/cmd/scale/scale.go | 34 ++++++++-----------
 test/cmd/core.sh                              |  9 +++++
 2 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/staging/src/k8s.io/kubectl/pkg/cmd/scale/scale.go b/staging/src/k8s.io/kubectl/pkg/cmd/scale/scale.go
index 9571351d40e..2aaa99191a9 100644
--- a/staging/src/k8s.io/kubectl/pkg/cmd/scale/scale.go
+++ b/staging/src/k8s.io/kubectl/pkg/cmd/scale/scale.go
@@ -209,13 +209,10 @@ func (o *ScaleOptions) RunScale() error {
 		return err
 	}
 
-	infos := []*resource.Info{}
-	r.Visit(func(info *resource.Info, err error) error {
-		if err == nil {
-			infos = append(infos, info)
-		}
-		return nil
-	})
+	infos, err := r.Infos()
+	if err != nil {
+		return err
+	}
 
 	if len(o.ResourceVersion) != 0 && len(infos) > 1 {
 		return fmt.Errorf("cannot use --resource-version with multiple resources")
@@ -234,17 +231,16 @@ func (o *ScaleOptions) RunScale() error {
 		waitForReplicas = scale.NewRetryParams(1*time.Second, o.Timeout)
 	}
 
-	counter := 0
-	err = r.Visit(func(info *resource.Info, err error) error {
-		if err != nil {
-			return err
-		}
-		counter++
+	if len(infos) == 0 {
+		return fmt.Errorf("no objects passed to scale")
+	}
 
+	for _, info := range infos {
 		mapping := info.ResourceMapping()
 		if o.dryRunStrategy == cmdutil.DryRunClient {
 			return o.PrintObj(info.Object, o.Out)
 		}
+
 		if err := o.scaler.Scale(info.Namespace, info.Name, uint(o.Replicas), precondition, retry, waitForReplicas, mapping.Resource, o.dryRunStrategy == cmdutil.DryRunServer); err != nil {
 			return err
 		}
@@ -263,14 +259,12 @@ func (o *ScaleOptions) RunScale() error {
 			}
 		}
 
-		return o.PrintObj(info.Object, o.Out)
-	})
-	if err != nil {
-		return err
-	}
-	if counter == 0 {
-		return fmt.Errorf("no objects passed to scale")
+		err := o.PrintObj(info.Object, o.Out)
+		if err != nil {
+			return err
+		}
 	}
+
 	return nil
 }
 
diff --git a/test/cmd/core.sh b/test/cmd/core.sh
index 1ce79d8188a..4733c9212fe 100755
--- a/test/cmd/core.sh
+++ b/test/cmd/core.sh
@@ -1289,6 +1289,15 @@ run_rc_tests() {
   # Clean-up
   kubectl delete deployment/nginx-deployment "${kube_flags[@]}"
 
+  ### Scale a deployment with piped input
+  kubectl create -f test/fixtures/doc-yaml/user-guide/deployment.yaml "${kube_flags[@]}"
+  # Command
+  kubectl get deployment/nginx-deployment -o json | kubectl scale --replicas=2 -f -
+  # Post-condition: 2 replica for nginx-deployment
+  kube::test::get_object_assert 'deployment nginx-deployment' "{{${deployment_replicas:?}}}" '2'
+  # Clean-up
+  kubectl delete deployment/nginx-deployment "${kube_flags[@]}"
+
   ### Expose deployments by creating a service
   # Uses deployment selectors for created service
   output_message=$(kubectl expose -f test/fixtures/pkg/kubectl/cmd/expose/appsv1deployment.yaml --port 80 2>&1 "${kube_flags[@]}")