没有顺序命名的状态集？

Question

这里是k8s新手。

StatefulSets允许创建带有a)预定义名称和b)订单的豆荚。在我的情况下，我不需要命令(b)，这是给我带来麻烦。(a)在我的情况下是有用的，因为我需要保持在货柜死亡时的状态。

举个例子，我有po-0，po-1，po-2，只是想让po-0死掉，但这就是所发生的事情：

预计这将：

  1. [ pod-0:Running, pod-1:Running, pod-2:Running ]
  2. My app needs to scale to 2 replicas by killing pod-0, so "k delete pod/pod-0" and "Replicas: 2"
  3. [ pod-0:terminating, pod-1:Running, pod-2:Running ]

，我想保持这种状态！

4. [ pod-1:Running, pod-2:Running ]

这，我不想！，但不能阻止K8s做：

5. [ pod-0:Starting, pod-1:Running, pod-2:Running ] (K8s shifts the pipe!!!)
6. [ pod-0:Running, pod-1:Running, pod-2:Terminating ] (K8s shifts the pipe!!!)
7. [ pod-0:Running, pod-1:Running ] (K8s shifts the pipe!!!)

如何使用K8s (保持一组非顺序命名的豆荚)实现所需的行为？

我已经看到了一个很有前途的"AdvancedStatefulSet"(https://openkruise.io/en-us/docs/advanced_statefulset.html)，它允许这样做，但是该产品还不适合生产。至少，它不工作在迷你库(Minkube1.16.0，码头19.03.13，OpenKruise 0.7.0)。

有人要我的部署文件，如下所示：

kind: StatefulSet
apiVersion: apps/v1

metadata:
  name: contextcf
  labels:
    name: contextcf
spec:
  serviceName: contextcf
  selector:
    matchLabels:
      name: contextcf
  replicas: 3
  template:
    metadata:
      labels:
        name: contextcf
    spec:
      containers:
        - name: contextcf
          image: (my-registry)/contextcf:1.0.0
          ports:
            - name: web
              containerPort: 80
# Volume sections removed, no issues there. The application is a simple as this.

Answer 1

你能附上你的YAML文件吗？

我有吊舱-0，吊舱-1，吊舱-2，我只想让吊舱-0死，但这就是发生的事情。

我不能用最简单的StatefulSet复制这个

$ cat sts.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx # has to match .spec.template.metadata.labels
  serviceName: "nginx"
  replicas: 3 # by default is 1
  template:
    metadata:
      labels:
        app: nginx # has to match .spec.selector.matchLabels
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: k8s.gcr.io/nginx-slim:0.8
        ports:
        - containerPort: 80
          name: web

新创建的由StatefulSet控制的豆荚

$ k -n test2 get pods -o wide
NAME    READY   STATUS    RESTARTS   AGE   IP             NODE       NOMINATED NODE   READINESS GATES
web-0   1/1     Running   0          19s   10.8.252.144   k8s-vm04   <none>           <none>
web-1   1/1     Running   0          12s   10.8.252.76    k8s-vm03   <none>           <none>
web-2   1/1     Running   0          6s    10.8.253.8     k8s-vm02   <none>           <none>

尝试删除web-0

$ k -n test2 delete pod web-0
pod "web-0" deleted

Web0处于终止状态。

$ k -n test2 get pods -o wide
NAME    READY   STATUS        RESTARTS   AGE   IP             NODE       NOMINATED NODE   READINESS GATES
web-0   0/1     Terminating   0          47s   10.8.252.144   k8s-vm04   <none>           <none>
web-1   1/1     Running       0          40s   10.8.252.76    k8s-vm03   <none>           <none>
web-2   1/1     Running       0          34s   10.8.253.8     k8s-vm02   <none>           <none>

web-0正在创建状态。

$ k -n test2 get pods -o wide
NAME    READY   STATUS              RESTARTS   AGE   IP            NODE       NOMINATED NODE   READINESS GATES
web-0   0/1     ContainerCreating   0          1s    <none>        k8s-vm04   <none>           <none>
web-1   1/1     Running             0          45s   10.8.252.76   k8s-vm03   <none>           <none>
web-2   1/1     Running             0          39s   10.8.253.8    k8s-vm02   <none>           <none>

所有的吊舱都在运行

NAME    READY   STATUS    RESTARTS   AGE     IP             NODE       NOMINATED NODE   READINESS GATES
web-0   1/1     Running   0          1m21s   10.8.252.145   k8s-vm04   <none>           <none>
web-1   1/1     Running   0          2m59s   10.8.252.76    k8s-vm03   <none>           <none>
web-2   1/1     Running   0          2m5s    10.8.253.8     k8s-vm02   <none>           <none>

其他吊舱仍在运行，没有处于终止状态。

如果您讨论缩放StatefulSet，这个statefulset.spec.podManagementPolicy可能会对您有所帮助。

$ k explain statefulset.spec.podManagementPolicy
KIND:     StatefulSet
VERSION:  apps/v1

FIELD:    podManagementPolicy <string>

DESCRIPTION:
     podManagementPolicy controls how pods are created during initial scale up,
     when replacing pods on nodes, or when scaling down. The default policy is
     `OrderedReady`, where pods are created in increasing order (pod-0, then
     pod-1, etc) and the controller will wait until each pod is ready before
     continuing. When scaling down, the pods are removed in the opposite order.
     The alternative policy is `Parallel` which will create pods in parallel to
     match the desired scale without waiting, and on scale down will delete all
     pods at once.