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orphan_pods_cleaner.go
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/
orphan_pods_cleaner.go
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// Copyright 2018 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package member
import (
"github.com/golang/glog"
"github.com/pingcap/tidb-operator/pkg/apis/pingcap.com/v1alpha1"
"github.com/pingcap/tidb-operator/pkg/controller"
"github.com/pingcap/tidb-operator/pkg/label"
v1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
corelisters "k8s.io/client-go/listers/core/v1"
)
const (
skipReasonOrphanPodsCleanerIsNotPDOrTiKV = "orphan pods cleaner: member type is not pd or tikv"
skipReasonOrphanPodsCleanerPVCNameIsEmpty = "orphan pods cleaner: pvcName is empty"
skipReasonOrphanPodsCleanerPVCIsFound = "orphan pods cleaner: pvc is found"
skipReasonOrphanPodsCleanerPodIsNotPending = "orphan pods cleaner: pod is not pending"
skipReasonOrphanPodsCleanerPodIsNotFound = "orphan pods cleaner: pod does not exist anymore"
skipReasonOrphanPodsCleanerPodChanged = "orphan pods cleaner: pod changed before deletion"
)
// OrphanPodsCleaner implements the logic for cleaning the orphan pods(has no pvc)
//
// In scaling out and failover, we will try to delete the old PVC to prevent it
// from being used by the new pod. However, the PVC might not be deleted
// immediately in the apiserver because of finalizers (e.g.
// kubernetes.io/pvc-protection) and the statefulset controller may not have
// received PVC delete event when it tries to create the new replica and the
// new pod will be pending forever because no PVC to use. We need to clean
// these orphan pods and let the statefulset controller to create PVC(s) for
// them.
//
// https://github.com/kubernetes/kubernetes/blob/84fe3db5cf58bf0fc8ff792b885465ceaf70a435/pkg/controller/statefulset/stateful_pod_control.go#L175-L199
//
type OrphanPodsCleaner interface {
Clean(*v1alpha1.TidbCluster) (map[string]string, error)
}
type orphanPodsCleaner struct {
podLister corelisters.PodLister
podControl controller.PodControlInterface
pvcLister corelisters.PersistentVolumeClaimLister
kubeCli kubernetes.Interface
}
// NewOrphanPodsCleaner returns a OrphanPodsCleaner
func NewOrphanPodsCleaner(podLister corelisters.PodLister,
podControl controller.PodControlInterface,
pvcLister corelisters.PersistentVolumeClaimLister,
kubeCli kubernetes.Interface) OrphanPodsCleaner {
return &orphanPodsCleaner{podLister, podControl, pvcLister, kubeCli}
}
func (opc *orphanPodsCleaner) Clean(tc *v1alpha1.TidbCluster) (map[string]string, error) {
ns := tc.GetNamespace()
// for unit test
skipReason := map[string]string{}
selector, err := label.New().Instance(tc.GetLabels()[label.InstanceLabelKey]).Selector()
if err != nil {
return skipReason, err
}
pods, err := opc.podLister.Pods(ns).List(selector)
if err != nil {
return skipReason, err
}
for _, pod := range pods {
podName := pod.GetName()
l := label.Label(pod.Labels)
if !(l.IsPD() || l.IsTiKV()) {
skipReason[podName] = skipReasonOrphanPodsCleanerIsNotPDOrTiKV
continue
}
if pod.Status.Phase != v1.PodPending {
skipReason[podName] = skipReasonOrphanPodsCleanerPodIsNotPending
continue
}
// TODO support multiple pvcs case?
var pvcName string
for _, vol := range pod.Spec.Volumes {
if vol.PersistentVolumeClaim != nil {
pvcName = vol.PersistentVolumeClaim.ClaimName
break
}
}
if pvcName == "" {
skipReason[podName] = skipReasonOrphanPodsCleanerPVCNameIsEmpty
continue
}
var err error
// check informer cache
_, err = opc.pvcLister.PersistentVolumeClaims(ns).Get(pvcName)
if err == nil {
skipReason[podName] = skipReasonOrphanPodsCleanerPVCIsFound
continue
}
if !errors.IsNotFound(err) {
return skipReason, err
}
// if PVC not found in cache, re-check from apiserver directly to make sure the PVC really not exist
_, err = opc.kubeCli.CoreV1().PersistentVolumeClaims(ns).Get(pvcName, metav1.GetOptions{})
if err == nil {
skipReason[podName] = skipReasonOrphanPodsCleanerPVCIsFound
continue
}
if !errors.IsNotFound(err) {
return skipReason, err
}
// if the PVC is not found in apiserver (also informer cache) and the
// phase of the Pod is Pending, delete it and let the stateful
// controller to create the pod and its PVC(s) again
apiPod, err := opc.kubeCli.CoreV1().Pods(ns).Get(podName, metav1.GetOptions{})
if errors.IsNotFound(err) {
skipReason[podName] = skipReasonOrphanPodsCleanerPodIsNotFound
continue
}
if err != nil {
return skipReason, err
}
// try our best to avoid deleting wrong object in apiserver
// TODO upgrade to use deleteOption.Preconditions.ResourceVersion in client-go 1.14+
if apiPod.UID != pod.UID || apiPod.ResourceVersion != pod.ResourceVersion {
skipReason[podName] = skipReasonOrphanPodsCleanerPodChanged
continue
}
err = opc.podControl.DeletePod(tc, pod)
if err != nil {
glog.Errorf("orphan pods cleaner: failed to clean orphan pod: %s/%s, %v", ns, podName, err)
return skipReason, err
}
glog.Infof("orphan pods cleaner: clean orphan pod: %s/%s successfully", ns, podName)
}
return skipReason, nil
}
type fakeOrphanPodsCleaner struct{}
// NewFakeOrphanPodsCleaner returns a fake orphan pods cleaner
func NewFakeOrphanPodsCleaner() OrphanPodsCleaner {
return &fakeOrphanPodsCleaner{}
}
func (fopc *fakeOrphanPodsCleaner) Clean(_ *v1alpha1.TidbCluster) (map[string]string, error) {
return nil, nil
}