kubernetes/pkg/util/pod/pod.go
Clayton Coleman b252865479
kubelet: Avoid sending no-op patches
In an e2e run, out of 1857 pod status updates executed by the
Kubelet 453 (25%) were no-ops - they only contained the UID of
the pod and no status changes. If the patch is a no-op we can
avoid invoking the server and continue.
2020-02-26 23:06:38 -05:00

71 lines
2.6 KiB
Go

/*
Copyright 2018 The Kubernetes 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 pod
import (
"bytes"
"context"
"encoding/json"
"fmt"
v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/types"
"k8s.io/apimachinery/pkg/util/strategicpatch"
clientset "k8s.io/client-go/kubernetes"
)
// PatchPodStatus patches pod status. It returns true and avoids an update if the patch contains no changes.
func PatchPodStatus(c clientset.Interface, namespace, name string, uid types.UID, oldPodStatus, newPodStatus v1.PodStatus) (*v1.Pod, []byte, bool, error) {
patchBytes, unchanged, err := preparePatchBytesForPodStatus(namespace, name, uid, oldPodStatus, newPodStatus)
if err != nil {
return nil, nil, false, err
}
if unchanged {
return nil, patchBytes, true, nil
}
updatedPod, err := c.CoreV1().Pods(namespace).Patch(context.TODO(), name, types.StrategicMergePatchType, patchBytes, metav1.PatchOptions{}, "status")
if err != nil {
return nil, nil, false, fmt.Errorf("failed to patch status %q for pod %q/%q: %v", patchBytes, namespace, name, err)
}
return updatedPod, patchBytes, false, nil
}
func preparePatchBytesForPodStatus(namespace, name string, uid types.UID, oldPodStatus, newPodStatus v1.PodStatus) ([]byte, bool, error) {
oldData, err := json.Marshal(v1.Pod{
Status: oldPodStatus,
})
if err != nil {
return nil, false, fmt.Errorf("failed to Marshal oldData for pod %q/%q: %v", namespace, name, err)
}
newData, err := json.Marshal(v1.Pod{
ObjectMeta: metav1.ObjectMeta{UID: uid}, // only put the uid in the new object to ensure it appears in the patch as a precondition
Status: newPodStatus,
})
if err != nil {
return nil, false, fmt.Errorf("failed to Marshal newData for pod %q/%q: %v", namespace, name, err)
}
patchBytes, err := strategicpatch.CreateTwoWayMergePatch(oldData, newData, v1.Pod{})
if err != nil {
return nil, false, fmt.Errorf("failed to CreateTwoWayMergePatch for pod %q/%q: %v", namespace, name, err)
}
return patchBytes, bytes.Equal(patchBytes, []byte(fmt.Sprintf(`{"metadata":{"uid":%q}}`, uid))), nil
}