一、了解Statefulset
1、Statefulset保证了pod在重新调度后保留它们的标识（容器名）和状态。
2、Statefulset做到每个pod对应相对的PV卷，每个POD都可以拥用一组独立的数据卷。
3、提供稳定的网络标识，一个Statefulset创建的每个pod都有一个从零开始的顺序索引，这个体现在pod的名称和主机名上，同样还会体现在pod对应的固定存储上。
4、让pod拥用可预知的名称和主机名，有状态的pod有时候需要通过其主机名来定位，而无状态的pod则不需要。基于以上原因，一个Statefulset通常要求你创建一个用来记录每个pod网络标记的headless Service，通过这个Service，每个pod将拥用独立的DNS记录，比如说，一个属于default命名空间，名为foo的控制服务，它的一个pod名称为A-0,那么可以通过完整域名访问它：a-0.foo.default.svc.cluster.local。
二、通过NFS设备共享挂载权限
[root@test-operator nfs-volume]# pwd
/data/nfs-volume
[root@test-operator nfs-volume]# ll
总用量 0
drwxr-xr-x 2 root root 24 5月 20 22:49 web0
drwxr-xr-x 2 root root 24 5月 20 22:49 web1
[root@test-operator nfs-volume]# cat /etc/exports
/data/nfs-volume/web0 10.3.153.0/24(rw,no_root_squash)
/data/nfs-volume/web1 10.3.153.0/24(rw,no_root_squash)
[root@test-operator nfs-volume]# cat web0/index.html
This is Web0!!!!!!!!!
[root@test-operator nfs-volume]# cat web1/index.html
This is Web1!!!!!!!
三、根据NFS共享目录创建两个PV卷
#web0-pv卷
[root@test-nodes1 statefulset]# vi web0-pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv-web0
spec:
capacity:
storage: 1Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Recycle
nfs:
path: /data/nfs-volume/web0
server: test-operator.cedarhd.com
#web1-pv卷
[root@test-nodes1 statefulset]# vi web1-pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv-web1
spec:
capacity:
storage: 1Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Recycle
nfs:
path: /data/nfs-volume/web1
server: test-operator.cedarhd.com三、创建headless Service服务
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None #必须为None
selector:
app: nginx四、创建Statefulset
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: web
spec:
serviceName: "nginx"
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:alpine
ports:
- containerPort: 80
name: web
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 1Gi
五、验证创建结果
1、查看PV与PVC绑定情况
[root@test-nodes1 statefulset]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv-web0 1Gi RWO Recycle Bound default/www-web-0 39m
pv-web1 1Gi RWO Recycle Bound default/www-web-1 39m
备注：pv-web0绑定相应声明卷：www-web-0（默认表空间）2、查看pod运维情况
[root@test-nodes1 statefulset]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-0 1/1 Running 0 43m 172.7.22.8 test-nodes2.cedarhd.com
web-1 1/1 Running 0 40m 172.7.21.8 test-nodes1.cedarhd.com 3、验证两个pod的网站的相对挂载情况
[root@test-nodes1 statefulset]# curl 172.7.22.8
This is Web0!!!!!!!!!
[root@test-nodes1 statefulset]# curl 172.7.21.8
This is Web1!!!!!!!4、查看headless Service
[root@test-nodes1 statefulset]# kubectl get service -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
kubernetes ClusterIP 192.168.0.1 443/TCP 54d
nginx ClusterIP None 80/TCP 47m app=nginx 5、验证POD之间的DNS解释是否正常
[root@test-nodes1 statefulset]# kubectl get pod
NAME READY STATUS RESTARTS AGE
web-0 1/1 Running 0 48m
web-1 1/1 Running 0 45m
[root@test-nodes1 statefulset]# kubectl exec -ti web-0 /bin/sh
/ # ping web-1.nginx.default
PING web-1.nginx.default (172.7.21.8): 56 data bytes
64 bytes from 172.7.21.8: seq=0 ttl=62 time=0.289 ms
64 bytes from 172.7.21.8: seq=1 ttl=62 time=0.275 ms
备注：完整访问域名web-1.nginx.default.svc.cluster.local6、查看statefulset信息
[root@test-nodes1 statefulset]# kubectl get statefulset web -o wide
NAME READY AGE CONTAINERS IMAGES
web 2/2 51m nginx nginx:alpine7、删除其中一个pod，查看恢复后状态是否一致
[root@test-nodes1 statefulset]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-0 1/1 Running 0 53m 172.7.22.8 test-nodes2.cedarhd.com
web-1 1/1 Running 0 50m 172.7.21.8 test-nodes1.cedarhd.com
[root@test-nodes1 statefulset]# kubectl delete pod web-1
pod "web-1" deleted
[root@test-nodes1 statefulset]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-0 1/1 Running 0 53m 172.7.22.8 test-nodes2.cedarhd.com
web-1 1/1 Running 0 5s 172.7.21.8 test-nodes1.cedarhd.com
[root@test-nodes1 statefulset]# curl 172.7.21.8
This is Web1!!!!!!!
六、statefulset缩减与扩容
可用命令：
[root@test-nodes1 ~]# kubectl edit statefulset web
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: apps/v1
kind: StatefulSet
metadata:
creationTimestamp: "2020-05-21T02:53:49Z"
generation: 3
name: web
namespace: default
resourceVersion: "13473136"
selfLink: /apis/apps/v1/namespaces/default/statefulsets/web
uid: f2336d24-8eea-41c6-8236-b45fba9cebf4
spec:
podManagementPolicy: OrderedReady
replicas: 2 #扩缩容副本数
revisionHistoryLimit: 10
selector:
matchLabels:
app: nginx
serviceName: nginx
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec: