kubernetes 删除资源对象策略分析

叁歲伎倆 2022-03-26 05:58 492阅读 0赞

本文分析的是kubernetes 删除资源对象的策略  
具体源码在$GOPATH/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/apis/meta/v1/types.go文件中  
![type code][]  
策略  
![de][]

DeleteOptions 结构体属性如下

type DeletionPropagation string
    
    const (
       // Orphans the dependents.
       DeletePropagationOrphan DeletionPropagation = "Orphan"
       // Deletes the object from the key-value store, the garbage collector will
       // delete the dependents in the background.
       DeletePropagationBackground DeletionPropagation = "Background"
       // The object exists in the key-value store until the garbage collector
       // deletes all the dependents whose ownerReference.blockOwnerDeletion=true
       // from the key-value store.  API sever will put the "foregroundDeletion"
       // finalizer on the object, and sets its deletionTimestamp.  This policy is
       // cascading, i.e., the dependents will be deleted with Foreground.
       DeletePropagationForeground DeletionPropagation = "Foreground"
    )
    
    // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
    
    // DeleteOptions may be provided when deleting an API object.
    type DeleteOptions struct {
       TypeMeta `json:",inline"`
    
       // The duration in seconds before the object should be deleted. Value must be non-negative integer.
       // The value zero indicates delete immediately. If this value is nil, the default grace period for the
       // specified type will be used.
       // Defaults to a per object value if not specified. zero means delete immediately.
       // +optional
       GracePeriodSeconds *int64 `json:"gracePeriodSeconds,omitempty" protobuf:"varint,1,opt,name=gracePeriodSeconds"`
    
       // Must be fulfilled before a deletion is carried out. If not possible, a 409 Conflict status will be
       // returned.
       // +optional
       Preconditions *Preconditions `json:"preconditions,omitempty" protobuf:"bytes,2,opt,name=preconditions"`
    
       // Deprecated: please use the PropagationPolicy, this field will be deprecated in 1.7.
       // Should the dependent objects be orphaned. If true/false, the "orphan"
       // finalizer will be added to/removed from the object's finalizers list.
       // Either this field or PropagationPolicy may be set, but not both.
       // +optional
       OrphanDependents *bool `json:"orphanDependents,omitempty" protobuf:"varint,3,opt,name=orphanDependents"`
    
       // Whether and how garbage collection will be performed.
       // Either this field or OrphanDependents may be set, but not both.
       // The default policy is decided by the existing finalizer set in the
       // metadata.finalizers and the resource-specific default policy.
       // Acceptable values are: 'Orphan' - orphan the dependents; 'Background' -
       // allow the garbage collector to delete the dependents in the background;
       // 'Foreground' - a cascading policy that deletes all dependents in the
       // foreground.
       // +optional
       PropagationPolicy *DeletionPropagation `json:"propagationPolicy,omitempty" protobuf:"varint,4,opt,name=propagationPolicy"`
    }

从以上源码内容可以看出，有三种删除策略

Foreground:删除控制器之前，所管理的资源对象必须先删除
    Background：删除控制器后，所管理的资源对象由GC删除
    Orphan：只删除控制器对象,不删除控制器所管理的资源对象

接下来验证这三种策略，这个需要kube-apiserver开启8080端口，直接通过`kubectl proxy 8080`启动，采用的是curl工具  
**1.Foreground policy**  
创建 deployment

$kubectl run my-nginx --image=nginx -n qinzhao 
    deployment.apps/my-nginx created

验证

curl -XDELETE -H "Content-Type: application/json"  localhost:8080/apis/extensions/v1beta1/namespaces/qinzhao/deployments/my-nginx -d '{"kind":"DeleteOptions","apiVersion":"v1","propagationPolicy":"Foreground"}'
    {
      "kind": "Deployment",
      "apiVersion": "extensions/v1beta1",
      "metadata": {
        "name": "my-nginx",
        "namespace": "qinzhao",
        "selfLink": "/apis/extensions/v1beta1/namespaces/qinzhao/deployments/my-nginx",
        "uid": "5c3e7e1a-188a-11e9-b0dd-5254eec04736",
        "resourceVersion": "15787798",
        "generation": 2,
        "creationTimestamp": "2019-01-15T05:56:54Z",
        "deletionTimestamp": "2019-01-15T06:32:14Z",
        "deletionGracePeriodSeconds": 0,
        "labels": {
          "run": "my-nginx"
        },
        "annotations": {
          "deployment.kubernetes.io/revision": "1"
        },
        "finalizers": [
          "foregroundDeletion"
        ]
      },
      "spec": {
        "replicas": 1,
        "selector": {
          "matchLabels": {
            "run": "my-nginx"
          }
        },
        "template": {
          "metadata": {
            "creationTimestamp": null,
            "labels": {
              "run": "my-nginx"
            }
          },
          "spec": {
            "containers": [
              {
                "name": "my-nginx",
                "image": "nginx",
                "resources": {
                  
                },
                "terminationMessagePath": "/dev/termination-log",
                "terminationMessagePolicy": "File",
                "imagePullPolicy": "Always"
              }
            ],
            "restartPolicy": "Always",
            "terminationGracePeriodSeconds": 30,
            "dnsPolicy": "ClusterFirst",
            "securityContext": {
              
            },
            "schedulerName": "default-scheduler"
          }
        },
        "strategy": {
          "type": "RollingUpdate",
          "rollingUpdate": {
            "maxUnavailable": "25%",
            "maxSurge": "25%"
          }
        },
        "revisionHistoryLimit": 2,
        "progressDeadlineSeconds": 600
      },
      "status": {
        "observedGeneration": 1,
        "replicas": 1,
        "updatedReplicas": 1,
        "readyReplicas": 1,
        "availableReplicas": 1,
        "conditions": [
          {
            "type": "Available",
            "status": "True",
            "lastUpdateTime": "2019-01-15T05:57:02Z",
            "lastTransitionTime": "2019-01-15T05:57:02Z",
            "reason": "MinimumReplicasAvailable",
            "message": "Deployment has minimum availability."
          },
          {
            "type": "Progressing",
            "status": "True",
            "lastUpdateTime": "2019-01-15T05:57:02Z",
            "lastTransitionTime": "2019-01-15T05:56:54Z",
            "reason": "NewReplicaSetAvailable",
            "message": "ReplicaSet \"my-nginx-8656859f54\" has successfully progressed."
          }
        ]
      }
    }

可以看到返回有deletionTimestamp，finalizers这两个属性

"deletionTimestamp": "2019-01-15T06:32:14Z",
     "finalizers": [
          "foregroundDeletion"
        ]

这个就是Foreground policy删除策略

**2.Background Policy**  
创建 deployment

$kubectl run my-nginx --image=nginx -n qinzhao 
    deployment.apps/my-nginx created

验证

**3.Orphan Policy策略**  
创建deployment

# kubectl run my-nginx --image=nginx -n qinzhao 
    deployment.apps/my-nginx created
    # kubectl get pod -n qinzhao 
    NAME                        READY     STATUS    RESTARTS   AGE
    demo02-599f688bf8-bw9sj     1/1       Running   0          5h
    my-nginx-8656859f54-j4x2l   1/1       Running   0          9s

验证

# curl -X DELETE localhost:8080/apis/extensions/v1beta1/namespaces/qinzhao/deployments/my-nginx -d '{"kind":"DeleteOptions","apiVersion":"v1","propagationPolicy":"Orphan"}' -H "Content-Type: application/json"
    {
      "kind": "Deployment",
      "apiVersion": "extensions/v1beta1",
      "metadata": {
        "name": "my-nginx",
        "namespace": "qinzhao",
        "selfLink": "/apis/extensions/v1beta1/namespaces/qinzhao/deployments/my-nginx",
        "uid": "a901a487-1890-11e9-b0dd-5254eec04736",
        "resourceVersion": "15789226",
        "generation": 2,
        "creationTimestamp": "2019-01-15T06:42:00Z",
        "deletionTimestamp": "2019-01-15T06:43:11Z",
        "deletionGracePeriodSeconds": 0,
        "labels": {
          "run": "my-nginx"
        },
        "annotations": {
          "deployment.kubernetes.io/revision": "1"
        },
        "finalizers": [
          "orphan"
        ]
      },
      "spec": {
        "replicas": 1,
        "selector": {
          "matchLabels": {
            "run": "my-nginx"
          }
        },
        "template": {
          "metadata": {
            "creationTimestamp": null,
            "labels": {
              "run": "my-nginx"
            }
          },
          "spec": {
            "containers": [
              {
                "name": "my-nginx",
                "image": "nginx",
                "resources": {
                  
                },
                "terminationMessagePath": "/dev/termination-log",
                "terminationMessagePolicy": "File",
                "imagePullPolicy": "Always"
              }
            ],
            "restartPolicy": "Always",
            "terminationGracePeriodSeconds": 30,
            "dnsPolicy": "ClusterFirst",
            "securityContext": {
              
            },
            "schedulerName": "default-scheduler"
          }
        },
        "strategy": {
          "type": "RollingUpdate",
          "rollingUpdate": {
            "maxUnavailable": "25%",
            "maxSurge": "25%"
          }
        },
        "revisionHistoryLimit": 2,
        "progressDeadlineSeconds": 600
      },
      "status": {
        "observedGeneration": 1,
        "replicas": 1,
        "updatedReplicas": 1,
        "readyReplicas": 1,
        "availableReplicas": 1,
        "conditions": [
          {
            "type": "Available",
            "status": "True",
            "lastUpdateTime": "2019-01-15T06:42:09Z",
            "lastTransitionTime": "2019-01-15T06:42:09Z",
            "reason": "MinimumReplicasAvailable",
            "message": "Deployment has minimum availability."
          },
          {
            "type": "Progressing",
            "status": "True",
            "lastUpdateTime": "2019-01-15T06:42:09Z",
            "lastTransitionTime": "2019-01-15T06:42:00Z",
            "reason": "NewReplicaSetAvailable",
            "message": "ReplicaSet \"my-nginx-8656859f54\" has successfully progressed."
          }
        ]
      }
    }