statefulset有狀態應用副本集
PetSet -> StatefulSet
1.文件且唯一的網路識別符號
2.穩定且持久的儲存
3.有序，平滑的部署和擴充套件
4.有序，平滑的刪除和終止
5.有序的滾動更新

三個元件：
headless service
StatefulSet
volumeClaimTemplate

實驗的前期準備條件：
master；192.168.68.10
node1：    192.168.68.20
node2： 192.168.68.30
node3:    192.168.68.40

node3準備：解析node3到本機，同步其他的master和node
各個節點安裝NFS
NFS目錄為：
[

啟動nfs
systemctl start nfs

檢視pvc
[[email protected] configmap]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM           STORAGECLASS   REASON    AGE
pv001     5Gi        RWO,RWX        Retain           Available                                            1d
pv002     7Gi        RWO,RWX        Retain           Bound       default/mypvc                            1d
pv003     8Gi        RWO,RWX        Retain           Available                                            1d
pv004     10Gi       RWO,RWX        Retain           Available                                            1d
pv005     12Gi       RWO,RWX        Retain           Available                                            1d
[
 
[email protected] configmap]# kubectl get pvc
NAME      STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mypvc     Bound     pv002     7Gi        RWO,RWX                       1d

刪除已經掛載的pvc

kubectl get pvc
kubectl delete pvc/mypvc

kubectl get pv
[[email protected] configmap]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM           STORAGECLASS   REASON    AGE
pv001     5Gi        RWO,RWX        Retain           Available                                            1d
pv002     7Gi        RWO,RWX        Retain           Released    default/mypvc                            1d
pv003     8Gi        RWO,RWX        Retain           Available                                            1d
pv004     10Gi       RWO,RWX        Retain           Available                                            1d
pv005     12Gi       RWO,RWX        Retain           Available                                            1d

Released    default/mypvc  狀態是已經釋放了


刪除所有的pv
kubectl delete pv --all

[
 
[email protected] configmap]# kubectl delete pv --all
persistentvolume "pv001" deleted
persistentvolume "pv002" deleted
persistentvolume "pv003" deleted
persistentvolume "pv004" deleted
persistentvolume "pv005" deleted
[[email protected] configmap]# kubectl get pv
No resources found.

開始重新建立pv
建立5個節點，5個PV

[[email protected] volumes]# cat pvs-demo.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv001
  labels:
    name: pv001
spec:
  nfs:
    path: /data/volumes/v1
    server: node3
  accessModes: ["ReadWriteOnce"]
  capacity:
    storage: 5Gi
--- 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv002
  labels:
    name: pv002
spec:
  nfs:
    path: /data/volumes/v2
    server: node3
  accessModes: ["ReadWriteMany","ReadWriteOnce"]
  capacity:
    storage: 5Gi
--- 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv003
  labels:
    name: pv003
spec:
  nfs:
    path: /data/volumes/v1
    server: node3
  accessModes: ["ReadWriteMany","ReadWriteOnce"]
  capacity:
    storage: 5Gi
--- 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv004
  labels:
    name: pv004
spec:
  nfs:
    path: /data/volumes/v4
    server: node3
  accessModes: ["ReadWriteMany","ReadWriteOnce"]
  capacity:
    storage: 5Gi
--- 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv005
  labels:
    name: pv005
spec:
  nfs:
    path: /data/volumes/v5
    server: node3
  accessModes: ["ReadWriteMany","ReadWriteOnce"]
  capacity:
    storage: 5Gi
--- 

[[email protected] volumes]# kubectl apply -f pvs-demo.yaml 
persistentvolume/pv001 created
persistentvolume/pv002 created
persistentvolume/pv003 created
persistentvolume/pv004 created
persistentvolume/pv005 created

[[email protected] volumes]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM     STORAGECLASS   REASON    AGE
pv001     5Gi        RWO,RWX        Retain           Available                                      21s
pv002     5Gi        RWO            Retain           Available                                      21s
pv003     5Gi        RWO,RWX        Retain           Available                                      21s
pv004     5Gi        RWO,RWX        Retain           Available                                      21s
pv005     5Gi        RWO,RWX        Retain           Available                                      21s

yaml檔案內容：
[[email protected] volumes]# cat stateful-demo-1.yaml 
apiVersion: v1
kind: Service
metadata:
  name: myapp
  labels:
    app: myapp
spec:
  ports: 
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: myapp-pod
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: myapp
spec:
  serviceName: myapp
  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

[[email protected] volumes]# kubectl apply -f stateful-demo.yaml 
service/myapp created
statefulset.apps/myapp created

檢視狀態

[[email protected] volumes]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          6s
myapp-1   1/1       Running   0          5s
myapp-2   1/1       Running   0          3s
[[email protected] volumes]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          11s
myapp-1   1/1       Running   0          10s
myapp-2   1/1       Running   0          8s
[[email protected] volumes]# kubectl get pvc
NAME                STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound     pv002     5Gi        RWO                           24s
myappdata-myapp-1   Bound     pv004     5Gi        RWO,RWX                       23s
myappdata-myapp-2   Bound     pv001     5Gi        RWO,RWX                       21s
[[email protected] volumes]# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d
myapp        ClusterIP   None         <none>        80/TCP    1m



[[email protected] volumes]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                       STORAGECLASS   REASON    AGE
pv001     5Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-2                            15m
pv002     5Gi        RWO            Retain           Bound       default/myappdata-myapp-0                            15m
pv003     5Gi        RWO,RWX        Retain           Available                                                        15m
pv004     5Gi        RWO,RWX        Retain           Bound       default/myappdata-myapp-1                            15m
pv005     5Gi        RWO,RWX        Retain           Available                                                        15m

通過上面發現：
pods 的名字是自己定義的
自動關聯三個5G的空間
自動繫結空間

[[email protected] volumes]# kubectl get sts
NAME      DESIRED   CURRENT   AGE
myapp     3         3         15m

測試刪除：

[[email protected] volumes]# kubectl delete -f stateful-demo-1.yaml 
service "myapp" deleted
statefulset.apps "myapp" deleted

通過監控發現：
kubectl get pods -w

[[email protected] ~]# kubectl get pods -w
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          21m
myapp-1   1/1       Running   0          20m
myapp-2   1/1       Running   0          20m
myapp-1   1/1       Terminating   0         21m
myapp-0   1/1       Terminating   0         21m
myapp-2   1/1       Terminating   0         21m
myapp-1   0/1       Terminating   0         21m
myapp-2   0/1       Terminating   0         21m
myapp-0   0/1       Terminating   0         21m
myapp-0   0/1       Terminating   0         21m
myapp-0   0/1       Terminating   0         21m
myapp-2   0/1       Terminating   0         21m
myapp-2   0/1       Terminating   0         21m
myapp-1   0/1       Terminating   0         21m
myapp-1   0/1       Terminating   0         21m

建立測試

[[email protected] volumes]# kubectl apply -f stateful-demo-1.yaml 
service/myapp created
statefulset.apps/myapp created

[[email protected] ~]# kubectl get pods -w
NAME      READY     STATUS    RESTARTS   AGE
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         1s
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         0s
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

###################################
由此發現，刪除是2,1,0
建立時0,1,2
無論怎麼建立都是繫結的固定的儲存卷

###################################

###################################
它支援滾動更新
###################################

注意：每個的pod名稱都是可以被解析的
myapp-0都是可以解析的

驗證

驗證：
[[email protected] ~]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          5m
myapp-1   1/1       Running   0          5m
myapp-2   1/1       Running   0          5m
[[email protected] ~]# kubectl exec -it myapp-0 /bin/sh

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

Name:      myapp-0.myapp.default.svc.cluster.local
Address 1: 10.244.2.65 myapp-0.myapp.default.svc.cluster.local
/ # nslookup myapp-1.myapp.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      myapp-1.myapp.default.svc.cluster.local
Address 1: 10.244.1.67 myapp-1.myapp.default.svc.cluster.local
/ # nslookup myapp-2.myapp.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      myapp-2.myapp.default.svc.cluster.local
Address 1: 10.244.2.66 myapp-2.myapp.default.svc.cluster.local

注意：解析的時候必須跟無頭服務
myapp-0 					pod名
myapp   					服務名
default.svc.cluster.local 	名稱空間

規則格式：
pod_name.service_name.ns_name.svc.cluster.local

#################
擴容實驗：
將myapp服務擴容到5個
[[email protected] volumes]# kubectl scale sts myapp --replicas=5
statefulset.apps/myapp scale

監控：
[[email protected] ~]# kubectl get pods -w
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          14m
myapp-1   1/1       Running   0          14m
myapp-2   1/1       Running   0          14m
myapp-3   0/1       Pending   0         0s
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
myapp-4   0/1       Pending   0         0s
myapp-4   0/1       Pending   0         0s
myapp-4   0/1       Pending   0         0s
myapp-4   0/1       ContainerCreating   0         0s
myapp-4   1/1       Running   0         1s


[[email protected] volumes]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          15m
myapp-1   1/1       Running   0          15m
myapp-2   1/1       Running   0          15m
myapp-3   1/1       Running   0          1m
myapp-4   1/1       Running   0          1m

[[email protected] volumes]# kubectl get pvc
NAME                STATUS    VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound     pv002     5Gi        RWO                           39m
myappdata-myapp-1   Bound     pv004     5Gi        RWO,RWX                       39m
myappdata-myapp-2   Bound     pv001     5Gi        RWO,RWX                       39m
myappdata-myapp-3   Bound     pv003     5Gi        RWO,RWX                       1m
myappdata-myapp-4   Bound     pv005     5Gi        RWO,RWX                       1m


#################

縮減實驗：

[[email protected] volumes]# kubectl scale sts myapp --replicas=2
或者：
[[email protected] volumes]# kubectl patch sts myapp -p '{"spec":{"replicas":2}}'
statefulset.apps/myapp patched

監控：可以發現是逆序的
[[email protected] ~]# kubectl get pods -w
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          17m
myapp-1   1/1       Running   0          17m
myapp-2   1/1       Running   0          17m
myapp-3   1/1       Running   0          2m
myapp-4   1/1       Running   0          2m
myapp-4   1/1       Terminating   0         3m
myapp-4   0/1       Terminating   0         3m
myapp-4   0/1       Terminating   0         3m
myapp-4   0/1       Terminating   0         3m
myapp-3   1/1       Terminating   0         3m
myapp-3   0/1       Terminating   0         3m
myapp-3   0/1       Terminating   0         3m
myapp-3   0/1       Terminating   0         3m
myapp-2   1/1       Terminating   0         18m
myapp-2   0/1       Terminating   0         18m
myapp-2   0/1       Terminating   0         18m
myapp-2   0/1       Terminating   0         18m

[[email protected] volumes]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
myapp-0   1/1       Running   0          19m
myapp-1   1/1       Running   0          19m
[[email protected] volumes]# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d
myapp        ClusterIP   None         <none>        80/TCP    19m
[[email protected] volumes]# kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM                       STORAGECLASS   REASON    AGE
pv001     5Gi        RWO,RWX        Retain           Bound     default/myappdata-myapp-2                            43m
pv002     5Gi        RWO            Retain           Bound     default/myappdata-myapp-0                            43m
pv003     5Gi        RWO,RWX        Retain           Bound     default/myappdata-myapp-3                            43m
pv004     5Gi        RWO,RWX        Retain           Bound     default/myappdata-myapp-1                            43m
pv005     5Gi        RWO,RWX        Retain           Bound     default/myappdata-myapp-4                            43m

#################
更新實驗：
金絲雀更新：
先更新部分版本，如果使用沒有問題，然後再手動繼續更新後面的
例如有五個myapp：
myapp1，myapp2，myapp3，myapp4，myapp5，
我想更新大於3的
partition:N
    >=N
    >=0  所有的都更新

擴充套件Pod到5個

[[email protected] volumes]# kubectl patch sts myapp -p '{"spec":{"replicas":5}}'

kubectl patch sts myapp -p '{"spec":{"updateStrategy":{"rollingUpdate":{"partition":4}}}}'

檢視更新策略：
[[email protected] volumes]# kubectl describe sts myapp
Partition:        4


開始更新到V2版本
[[email protected] volumes]# kubectl set image sts/myapp myapp=ikubernetes/myapp:v2
statefulset.apps/myapp image updated

[[email protected] volumes]# kubectl get sts -o wide  控制器已經更新到v2
NAME      DESIRED   CURRENT   AGE       CONTAINERS   IMAGES
myapp     5         5         37m       myapp        ikubernetes/myapp:v2

kubectl describe pods myapp-0  到myapp-3
Image:          ikubernetes/myapp:v1

kubectl describe pods myapp-4
Image:          ikubernetes/myapp:v2

如果想更新全部到v2版本：
kubectl patch sts myapp -p '{"spec":{"updateStrategy":{"rollingUpdate":{"partition":0}}}}'
kubectl set image sts/myapp myapp=ikubernetes/myapp:v2
這樣就全部更新成功了