Kubernetes學習之路（十七）之statefulset控制器

時間 2019-11-06

標籤 kubernetes 學習之路十七 statefulset 控制器简体版

原文原文鏈接

目錄html

1、statefulset簡介

從前面的學習咱們知道使用Deployment建立的pod是無狀態的，當掛載了Volume以後，若是該pod掛了，Replication Controller會再啓動一個pod來保證可用性，可是因爲pod是無狀態的，pod掛了就會和以前的Volume的關係斷開，新建立的Pod沒法找到以前的Pod。可是對於用戶而言，他們對底層的Pod掛了是沒有感知的，可是當Pod掛了以後就沒法再使用以前掛載的存儲卷。node

爲了解決這一問題，就引入了StatefulSet用於保留Pod的狀態信息。nginx

StatefulSet是爲了解決有狀態服務的問題（對應Deployments和ReplicaSets是爲無狀態服務而設計），其應用場景包括：web

一、穩定的持久化存儲，即Pod從新調度後仍是能訪問到相同的持久化數據，基於PVC來實現
二、穩定的網絡標誌，即Pod從新調度後其PodName和HostName不變，基於Headless Service（即沒有Cluster IP的Service）來實現
三、有序部署，有序擴展，即Pod是有順序的，在部署或者擴展的時候要依據定義的順序依次依次進行（即從0到N-1，在下一個Pod運行以前全部以前的Pod必須都是Running和Ready狀態），基於init containers來實現
四、有序收縮，有序刪除（即從N-1到0）
五、有序的滾動更新

從上面的應用場景能夠發現，StatefulSet由如下幾個部分組成：redis

Headless Service（無頭服務）用於爲Pod資源標識符生成可解析的DNS記錄。

volumeClaimTemplates （存儲卷申請模板）基於靜態或動態PV供給方式爲Pod資源提供專有的固定存儲。

StatefulSet，用於管控Pod資源。

2、爲何要有headless？？

在deployment中，每個pod是沒有名稱，是隨機字符串，是無序的。而statefulset中是要求有序的，每個pod的名稱必須是固定的。當節點掛了，重建以後的標識符是不變的，每個節點的節點名稱是不能改變的。pod名稱是做爲pod識別的惟一標識符，必須保證其標識符的穩定而且惟一。
爲了實現標識符的穩定，這時候就須要一個headless service 解析直達到pod，還須要給pod配置一個惟一的名稱。docker

3、爲何要有volumeClainTemplate？？

大部分有狀態副本集都會用到持久存儲，好比分佈式系統來講，因爲數據是不同的，每一個節點都須要本身專用的存儲節點。而在deployment中pod模板中建立的存儲卷是一個共享的存儲卷，多個pod使用同一個存儲卷，而statefulset定義中的每個pod都不能使用同一個存儲卷，由此基於pod模板建立pod是不適應的，這就須要引入volumeClainTemplate，當在使用statefulset建立pod時，會自動生成一個PVC，從而請求綁定一個PV，從而有本身專用的存儲卷。Pod名稱、PVC和PV關係圖以下：
vim

4、statefulSet使用演示

在建立StatefulSet以前須要準備的東西，值得注意的是建立順序很是關鍵，建立順序以下：
一、Volume
二、Persistent Volume
三、Persistent Volume Claim
四、Service
五、StatefulSet
Volume能夠有不少種類型，好比nfs、glusterfs等，咱們這裏使用的ceph RBD來建立。api

（1）查看statefulset的定義

[root@k8s-master ~]# kubectl explain statefulset
KIND:     StatefulSet
VERSION:  apps/v1

DESCRIPTION:
     StatefulSet represents a set of pods with consistent identities. Identities
     are defined as: - Network: A single stable DNS and hostname. - Storage: As
     many VolumeClaims as requested. The StatefulSet guarantees that a given
     network identity will always map to the same storage identity.

FIELDS:
   apiVersion   <string>
   kind <string>
   metadata <Object>
   spec <Object>
   status   <Object>
[root@k8s-master ~]# kubectl explain statefulset.spec
KIND:     StatefulSet
VERSION:  apps/v1

RESOURCE: spec <Object>

DESCRIPTION:
     Spec defines the desired identities of pods in this set.

     A StatefulSetSpec is the specification of a StatefulSet.

FIELDS:
   podManagementPolicy  <string>  #Pod管理策略
   replicas <integer>    #副本數量
   revisionHistoryLimit <integer>   #歷史版本限制
   selector <Object> -required-    #選擇器，必選項
   serviceName  <string> -required-  #服務名稱，必選項
   template <Object> -required-    #模板，必選項
   updateStrategy   <Object>       #更新策略
   volumeClaimTemplates <[]Object>   #存儲卷申請模板，列表對象形式

（2）清單定義StatefulSet

如上所述，一個完整的StatefulSet控制器由一個Headless Service、一個StatefulSet和一個volumeClaimTemplate組成。以下資源清單中的定義：tomcat

[root@k8s-master mainfests]# vim stateful-demo.yaml
apiVersion: v1
kind: Service
metadata:
  name: myapp-svc
  labels:
    app: myapp-svc
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: myapp-pod
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: myapp
spec:
  serviceName: myapp-svc
  replicas: 3
  selector:
    matchLabels:
      app: myapp-pod
  template:
    metadata:
      labels:
        app: myapp-pod
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: myappdata
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: myappdata
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 2Gi

解析上例：因爲StatefulSet資源依賴於一個實現存在的Headless類型的Service資源，因此須要先定義一個名爲myapp-svc的Headless Service資源，用於爲關聯到每一個Pod資源建立DNS資源記錄。接着定義了一個名爲myapp的StatefulSet資源，它經過Pod模板建立了3個Pod資源副本，並基於volumeClaimTemplates向前面建立的PV進行了請求大小爲2Gi的專用存儲卷。網絡

（3）刪除前期的操做

[root@k8s-master mainfests]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM           STORAGECLASS   REASON    AGE
pv001     1Gi        RWO,RWX        Retain           Available                                            23h
pv002     2Gi        RWO            Retain           Available                                            23h
pv003     2Gi        RWO,RWX        Retain           Bound       default/mypvc                            23h
pv004     4Gi        RWO,RWX        Retain           Available                                            23h
pv005     5Gi        RWO,RWX        Retain           Available                                            23h
[root@k8s-master mainfests]# kubectl delete pods pod-vol-pvc
pod "pod-vol-pvc" deleted
[root@k8s-master mainfests]# kubectl delete pods/pod-cm-3 pods/pod-secret-env pods/pod-vol-hostpath
pod "pod-cm-3" deleted
pod "pod-secret-env" deleted
pod "pod-vol-hostpath" deleted

[root@k8s-master mainfests]# kubectl delete deploy/myapp-backend-pod deploy/tomcat-deploy
deployment.extensions "myapp-backend-pod" deleted
deployment.extensions "tomcat-deploy" deleted

[root@k8s-master mainfests]# kubectl delete pods pod-vol-pvc
pod "pod-vol-pvc" deleted
[root@k8s-master mainfests]# kubectl delete pods/pod-cm-3 pods/pod-secret-env pods/pod-vol-hostpath
pod "pod-cm-3" deleted
pod "pod-secret-env" deleted
pod "pod-vol-hostpath" deleted

[root@k8s-master mainfests]# kubectl delete deploy/myapp-backend-pod deploy/tomcat-deploy
deployment.extensions "myapp-backend-pod" deleted
deployment.extensions "tomcat-deploy" deleted

persistentvolumeclaim "mypvc" deleted
[root@k8s-master mainfests]# kubectl delete pv --all
persistentvolume "pv001" deleted
persistentvolume "pv002" deleted
persistentvolume "pv003" deleted
persistentvolume "pv004" deleted
persistentvolume "pv005" deleted

（4）修改pv的大小爲2Gi

[root@k8s-master ~]# cd mainfests/volumes
[root@k8s-master volumes]# vim pv-demo.yaml 
[root@k8s-master volumes]# kubectl apply -f pv-demo.yaml 
persistentvolume/pv001 created
persistentvolume/pv002 created
persistentvolume/pv003 created
persistentvolume/pv004 created
persistentvolume/pv005 created
[root@k8s-master volumes]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM     STORAGECLASS   REASON    AGE
pv001     1Gi        RWO,RWX        Retain           Available                                      5s
pv002     2Gi        RWO            Retain           Available                                      5s
pv003     2Gi        RWO,RWX        Retain           Available                                      5s
pv004     2Gi        RWO,RWX        Retain           Available                                      5s
pv005     2Gi        RWO,RWX        Retain           Available                                      5s

（5）建立statefulset

[root@k8s-master mainfests]# kubectl apply -f stateful-demo.yaml 
service/myapp-svc created
statefulset.apps/myapp created
[root@k8s-master mainfests]# kubectl get svc  #查看建立的無頭服務myapp-svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)             AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP             50d
myapp-svc    ClusterIP   None             <none>        80/TCP              38s
[root@k8s-master mainfests]# kubectl get sts    #查看statefulset
NAME      DESIRED   CURRENT   AGE
myapp     3         3         55s
[root@k8s-master mainfests]# kubectl get pvc    #查看pvc綁定
NAME                STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound     pv002     2Gi        RWO                           1m
myappdata-myapp-1   Bound     pv003     2Gi        RWO,RWX                       1m
myappdata-myapp-2   Bound     pv004     2Gi        RWO,RWX                       1m
[root@k8s-master mainfests]# kubectl get pv    #查看pv綁定
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                       STORAGECLASS   REASON    AGE
pv001     1Gi        RWO,RWX        Retain           Available                                                        6m
pv002     2Gi        RWO            Retain           Bound       default/myappdata-myapp-0                            6m
pv003     2Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-1                            6m
pv004     2Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-2                            6m
pv005     2Gi        RWO,RWX        Retain           Available                                                        6m

[root@k8s-master mainfests]# kubectl get pods   #查看Pod信息
NAME                     READY     STATUS    RESTARTS   AGE
myapp-0                  1/1       Running   0          2m
myapp-1                  1/1       Running   0          2m
myapp-2                  1/1       Running   0          2m
pod-vol-demo             2/2       Running   0          1d
redis-5b5d6fbbbd-q8ppz   1/1       Running   1          2d

當刪除的時候是從myapp-2開始進行刪除的，關閉是逆向關閉

[root@k8s-master mainfests]# kubectl delete -f stateful-demo.yaml 
service "myapp-svc" deleted
statefulset.apps "myapp" deleted

[root@k8s-master ~]# kubectl get pods -w
NAME                     READY     STATUS    RESTARTS   AGE
filebeat-ds-hxgdx        1/1       Running   1          33d
filebeat-ds-s466l        1/1       Running   2          33d
myapp-0                  1/1       Running   0          3m
myapp-1                  1/1       Running   0          3m
myapp-2                  1/1       Running   0          3m
pod-vol-demo             2/2       Running   0          1d
redis-5b5d6fbbbd-q8ppz   1/1       Running   1          2d
myapp-0   1/1       Terminating   0         3m
myapp-2   1/1       Terminating   0         3m
myapp-1   1/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-0   0/1       Terminating   0         3m
myapp-2   0/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-0   0/1       Terminating   0         4m
myapp-0   0/1       Terminating   0         4m
myapp-2   0/1       Terminating   0         3m
myapp-2   0/1       Terminating   0         3m

此時PVC依舊存在的，再從新建立pod時，依舊會從新去綁定原來的pvc
[root@k8s-master mainfests]# kubectl apply -f stateful-demo.yaml 
service/myapp-svc created
statefulset.apps/myapp created

[root@k8s-master mainfests]# kubectl get pvc
NAME                STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound     pv002     2Gi        RWO                           5m
myappdata-myapp-1   Bound     pv003     2Gi        RWO,RWX                       5m
myappdata-myapp-2   Bound     pv004     2Gi        RWO,RWX                       5m

[root@k8s-master mainfests]# kubectl delete -f stateful-demo.yaml 
service "myapp-svc" deleted
statefulset.apps "myapp" deleted

[root@k8s-master ~]# kubectl get pods -w
NAME                     READY     STATUS    RESTARTS   AGE
filebeat-ds-hxgdx        1/1       Running   1          33d
filebeat-ds-s466l        1/1       Running   2          33d
myapp-0                  1/1       Running   0          3m
myapp-1                  1/1       Running   0          3m
myapp-2                  1/1       Running   0          3m
pod-vol-demo             2/2       Running   0          1d
redis-5b5d6fbbbd-q8ppz   1/1       Running   1          2d
myapp-0   1/1       Terminating   0         3m
myapp-2   1/1       Terminating   0         3m
myapp-1   1/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-0   0/1       Terminating   0         3m
myapp-2   0/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-1   0/1       Terminating   0         3m
myapp-0   0/1       Terminating   0         4m
myapp-0   0/1       Terminating   0         4m
myapp-2   0/1       Terminating   0         3m
myapp-2   0/1       Terminating   0         3m

此時PVC依舊存在的，再從新建立pod時，依舊會從新去綁定原來的pvc
[root@k8s-master mainfests]# kubectl apply -f stateful-demo.yaml 
service/myapp-svc created
statefulset.apps/myapp created

[root@k8s-master mainfests]# kubectl get pvc
NAME                STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound     pv002     2Gi        RWO                           5m
myappdata-myapp-1   Bound     pv003     2Gi        RWO,RWX                       5m
myappdata-myapp-2   Bound     pv004     2Gi        RWO,RWX                       5m

5、滾動更新、擴展伸縮、版本升級、修改更新策略

一、滾動更新

RollingUpdate 更新策略在 StatefulSet 中實現 Pod 的自動滾動更新。當StatefulSet的 .spec.updateStrategy.type 設置爲 RollingUpdate 時，默認爲：RollingUpdate。StatefulSet 控制器將在 StatefulSet 中刪除並從新建立每一個 Pod。它將以與 Pod 終止相同的順序進行（從最大的序數到最小的序數），每次更新一個 Pod。在更新其前身以前，它將等待正在更新的 Pod 狀態變成正在運行並就緒。以下操做的滾動更新是有2-0的順序更新。

[root@k8s-master mainfests]# vim stateful-demo.yaml  #修改image版本爲v2
.....
image: ikubernetes/myapp:v2
....
[root@k8s-master mainfests]# kubectl apply -f stateful-demo.yaml 
service/myapp-svc unchanged
statefulset.apps/myapp configured
[root@k8s-master ~]# kubectl get pods -w   #查看滾動更新的過程
NAME                     READY     STATUS    RESTARTS   AGE
myapp-0                  1/1       Running   0          36m
myapp-1                  1/1       Running   0          36m
myapp-2                  1/1       Running   0          36m

myapp-2   1/1       Terminating   0         36m
myapp-2   0/1       Terminating   0         36m
myapp-2   0/1       Terminating   0         36m
myapp-2   0/1       Terminating   0         36m
myapp-2   0/1       Pending   0         0s
myapp-2   0/1       Pending   0         0s
myapp-2   0/1       ContainerCreating   0         0s
myapp-2   1/1       Running   0         2s
myapp-1   1/1       Terminating   0         36m
myapp-1   0/1       Terminating   0         36m
myapp-1   0/1       Terminating   0         36m
myapp-1   0/1       Terminating   0         36m
myapp-1   0/1       Pending   0         0s
myapp-1   0/1       Pending   0         0s
myapp-1   0/1       ContainerCreating   0         0s
myapp-1   1/1       Running   0         1s
myapp-0   1/1       Terminating   0         37m
myapp-0   0/1       Terminating   0         37m
myapp-0   0/1       Terminating   0         37m
myapp-0   0/1       Terminating   0         37m

在建立的每個Pod中，每個pod本身的名稱都是能夠被解析的，以下：

[root@k8s-master ~]# kubectl get pods -o wide
NAME                     READY     STATUS    RESTARTS   AGE       IP            NODE
myapp-0                  1/1       Running   0          8m        10.244.1.62   k8s-node01
myapp-1                  1/1       Running   0          8m        10.244.2.49   k8s-node02
myapp-2                  1/1       Running   0          8m        10.244.1.61   k8s-node01

[root@k8s-master mainfests]# kubectl exec -it myapp-0 -- /bin/sh
/ # nslookup myapp-0.myapp-svc.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      myapp-0.myapp-svc.default.svc.cluster.local
Address 1: 10.244.1.62 myapp-0.myapp-svc.default.svc.cluster.local
/ # nslookup myapp-1.myapp-svc.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      myapp-1.myapp-svc.default.svc.cluster.local
Address 1: 10.244.2.49 myapp-1.myapp-svc.default.svc.cluster.local
/ # nslookup myapp-2.myapp-svc.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      myapp-2.myapp-svc.default.svc.cluster.local
Address 1: 10.244.1.61 myapp-2.myapp-svc.default.svc.cluster.local

從上面的解析，咱們能夠看到在容器當中能夠經過對Pod的名稱進行解析到ip。其解析的域名格式以下：
pod_name.service_name.ns_name.svc.cluster.local
eg: myapp-0.myapp.default.svc.cluster.local

二、擴展伸縮

[root@k8s-master mainfests]# kubectl scale sts myapp --replicas=4  #擴容副本增長到4個
statefulset.apps/myapp scaled
[root@k8s-master ~]# kubectl get pods -w  #動態查看擴容
NAME                     READY     STATUS    RESTARTS   AGE
myapp-0                  1/1       Running   0          23m
myapp-1                  1/1       Running   0          23m
myapp-2                  1/1       Running   0          23m

myapp-3   0/1       Pending   0         0s
myapp-3   0/1       Pending   0         0s
myapp-3   0/1       ContainerCreating   0         0s
myapp-3   1/1       Running   0         1s
[root@k8s-master mainfests]# kubectl get pv  #查看pv綁定
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                       STORAGECLASS   REASON    AGE
pv001     1Gi        RWO,RWX        Retain           Available                                                        1h
pv002     2Gi        RWO            Retain           Bound       default/myappdata-myapp-0                            1h
pv003     2Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-1                            1h
pv004     2Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-2                            1h
pv005     2Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-3                            1h

[root@k8s-master mainfests]# kubectl patch sts myapp -p '{"spec":{"replicas":2}}'  #打補丁方式縮容
statefulset.apps/myapp patched
[root@k8s-master ~]# kubectl get pods -w  #動態查看縮容
NAME                     READY     STATUS    RESTARTS   AGE
myapp-0                  1/1       Running   0          25m
myapp-1                  1/1       Running   0          25m
myapp-2                  1/1       Running   0          25m
myapp-3                  1/1       Running   0          1m
myapp-3   1/1       Terminating   0         2m
myapp-3   0/1       Terminating   0         2m
myapp-3   0/1       Terminating   0         2m
myapp-3   0/1       Terminating   0         2m
myapp-2   1/1       Terminating   0         26m
myapp-2   0/1       Terminating   0         26m
myapp-2   0/1       Terminating   0         27m
myapp-2   0/1       Terminating   0         27m

三、更新策略和版本升級

修改更新策略，以partition方式進行更新，更新值爲2，只有myapp編號大於等於2的纔會進行更新。相似於金絲雀部署方式。

[root@k8s-master mainfests]# kubectl patch sts myapp -p '{"spec":{"updateStrategy":{"rollingUpdate":{"partition":2}}}}'
statefulset.apps/myapp patched
[root@k8s-master ~]# kubectl get sts myapp
NAME      DESIRED   CURRENT   AGE
myapp     4         4         1h
[root@k8s-master ~]# kubectl describe sts myapp
Name:               myapp
Namespace:          default
CreationTimestamp:  Wed, 10 Oct 2018 21:58:24 -0400
Selector:           app=myapp-pod
Labels:             <none>
Annotations:        kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"apps/v1","kind":"StatefulSet","metadata":{"annotations":{},"name":"myapp","namespace":"default"},"spec":{"replicas":3,"selector":{"match...
Replicas:           4 desired | 4 total
Update Strategy:    RollingUpdate
  Partition:        2
......

版本升級，將image的版本升級爲v3，升級後對比myapp-2和myapp-1的image版本是不一樣的。這樣就實現了金絲雀發佈的效果。

[root@k8s-master mainfests]# kubectl set image sts/myapp myapp=ikubernetes/myapp:v3
statefulset.apps/myapp image updated
[root@k8s-master ~]# kubectl get sts -o wide
NAME      DESIRED   CURRENT   AGE       CONTAINERS   IMAGES
myapp     4         4         1h        myapp        ikubernetes/myapp:v3
[root@k8s-master ~]# kubectl get pods myapp-2 -o yaml |grep image
  - image: ikubernetes/myapp:v3
    imagePullPolicy: IfNotPresent
    image: ikubernetes/myapp:v3
    imageID: docker-pullable://ikubernetes/myapp@sha256:b8d74db2515d3c1391c78c5768272b9344428035ef6d72158fd9f6c4239b2c69

[root@k8s-master ~]# kubectl get pods myapp-1 -o yaml |grep image
  - image: ikubernetes/myapp:v2
    imagePullPolicy: IfNotPresent
    image: ikubernetes/myapp:v2
    imageID: docker-pullable://ikubernetes/myapp@sha256:85a2b81a62f09a414ea33b74fb8aa686ed9b168294b26b4c819df0be0712d358

將剩餘的Pod也更新版本，只須要將更新策略的partition值改成0便可，以下：

[root@k8s-master mainfests]#  kubectl patch sts myapp -p '{"spec":{"updateStrategy":{"rollingUpdate":{"partition":0}}}}'
statefulset.apps/myapp patched

[root@k8s-master ~]# kubectl get pods -w
NAME                     READY     STATUS    RESTARTS   AGE
myapp-0                  1/1       Running   0          58m
myapp-1                  1/1       Running   0          58m
myapp-2                  1/1       Running   0          13m
myapp-3                  1/1       Running   0          13m
myapp-1   1/1       Terminating   0         58m
myapp-1   0/1       Terminating   0         58m
myapp-1   0/1       Terminating   0         58m
myapp-1   0/1       Terminating   0         58m
myapp-1   0/1       Pending   0         0s
myapp-1   0/1       Pending   0         0s
myapp-1   0/1       ContainerCreating   0         0s
myapp-1   1/1       Running   0         2s
myapp-0   1/1       Terminating   0         58m
myapp-0   0/1       Terminating   0         58m
myapp-0   0/1       Terminating   0         58m
myapp-0   0/1       Terminating   0         58m
myapp-0   0/1       Pending   0         0s
myapp-0   0/1       Pending   0         0s
myapp-0   0/1       ContainerCreating   0         0s
myapp-0   1/1       Running   0         2s