One: Statefulset
StatefulSet is designed to solve the problem of stateless services. The corresponding Deployment and ReplicaSet are designed for stateless services, and their scenarios include:
1. Stable persistent storage, i.e. access to the same persistent data after Pod rescheduling, based on PVC
2. Stable network flags, i.e. PodName and HostName remain unchanged after a Pod reschedule, are based on Headless Service (that is, Service without Cluster IP)
3. Ordered deployment, ordered expansion, that is, Pod is ordered, deployed or expanded in the order defined (i.e., from 0 to N-1, all previous Pods must be Running and Ready before the next Pod runs), based on init containers
4. Orderly shrinking, orderly deleting (i.e. from N-1 to 0)
Because statefulset requires that the names of Pods be ordered, each Pod cannot be replaced at will, that is, even after the Pod is rebuilt, the name remains the same.Name each Pod on the back end.
As you can see from the above application scenarios, the StatefulSet consists of the following components: 1. Headless Service (headless-svc: headless service) for defining network flags.Because there is no IP address, it does not have load balancing capabilities.) 2. VolumeeClaimTemplates for creating PersistentVolumes 3. Define a StatefulSet for a specific application
StatefulSet:Pod controller.
RC, RS, Deployment, DS.Stateless services.
template: Pod s created from templates are in the same state (except name, IP, domain name)
It can be understood that any Pod can be deleted and replaced with a newly generated Pod.
Stateful services: The relevant time in the previous or multiple communications needs to be recorded as the classification standard for the next communication.For example: database services such as MySQL.(The name of a Pod cannot be changed at will.The directories for data persistence are also different, each Pod has its own unique directory for data persistence storage.)
Each Pod - - one PVC - - one PV for each PVC.
Test: Requirements
2. Create a namespace under your own name where all the following resources run.
Running an httpd web service with the statefuset resource requires three Pods, but each Pod has a different main interface content and requires proprietary data persistence. Try deleting one of the Pods to see if the newly generated Pods have the same data as the previous one.
1.Be based on NFS Services, Create NFS Service.
1.[root@master ~]# yum -y install nfs-utils rpcbind br/>2.[root@master ~]# mkdir /nfsdata
3.[root@master ~]# vim /etc/exports br/>4./nfsdata *(rw,sync,no_root_squash)
5.[root@master ~]# systemctl start nfs-server.service
6.[root@master ~]# systemctl start rpcbind br/>7.[root@master ~]# showmount -e
8.Export list for master:
9./nfsdata *
2. Create RBAC permissions
vim rbac-rolebind.yaml
apiVersion: v1
kind: Namespace
metadata:
name: lbs-test
apiVersion: v1
kind: ServiceAccount Establish rbac Authorized users.And define permissions
metadata:
name: nfs-provisioner
name: lbs-test
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: nfs-provisioner-runner
name: lbs-test
rules:
- apiGroups: [""]
resources: ["persistentvolumes"]
verbs: ["get", "list", "watch", "create", "delete"]
- apiGroups: [""]
resources: ["persistentvolumeclaims"]
verbs: ["get", "list", "watch", "update"]
- apiGroups: ["storage.k8s.io"]
resources: ["storageclasses"]
verbs: ["get", "list", "watch"]
- apiGroups: [""]
resources: ["events"]
verbs: ["watch", "create", "update", "patch"]
- apiGroups: [""]
resources: ["services", "endpoints"]
verbs: ["get","create","list", "watch","update"]
- apiGroups: ["extensions"]
resources: ["podsecuritypolicies"]
resourceNames: ["nfs-provisioner"]
verbs: ["use"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: run-nfs-provisioner
subjects:
- kind: ServiceAccount
name: nfs-provisioner
namespace: lbs-test If there is no namespace to add this default Default Otherwise Error
roleRef:
kind: ClusterRole
name: nfs-provisioner-runner
apiGroup: rbac.authorization.k8s.ioExecute yaml file:
1.[root@master yaml]# kubectl apply -f rbac-rolebind.yaml
2.namespace/lbh-test created
3.serviceaccount/nfs-provisioner created
4.clusterrole.rbac.authorization.k8s.io/nfs-provisioner-runner created
5.clusterrolebinding.rbac.authorization.k8s.io/run-nfs-provisioner created
3.Establish Deployment Resource object.
[root@master yaml]# vim nfs-deployment.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nfs-client-provisioner
name: lbs-test
spec:
replicas: 1#Number of copies is 1
strategy:
type: Recreate#Reset
template:
metadata:
labels:
app: nfs-client-provisioner
spec:
serviceAccount: nfs-provisioner#Designated Account
containers:
- name: nfs-client-provisioner
image: registry.cn-hangzhou.aliyuncs.com/open-ali/nfs-client-provisioner This image is used.
volumeMounts:
- name: nfs-client-root
mountPath: /persistentvolumes#Specify the mount directory within the container
env:
- name: PROVISIONER_NAME#Container built-in variables
value: bdqn#This is the name of the variable
- name: NFS_SERVER
value: 192.168.1.1
- name: NFS_PATH#Specify shared directory for Nfs
value: /nfsdata
volumes:#Specify nfs path and IP mounted in container
- name: nfs-client-root
nfs:
server: 192.168.1.1
path: /nfsdataExecute the yaml file and view the Pod: br/>1.[root@master yaml]# kubectl apply -f nfs-deployment.yaml
2.deployment.extensions/nfs-client-provisioner created br/>3.[root@master yaml]# kubectl get pod -n lbs-test
4.NAME READY STATUS RESTARTS AGE
5.nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 13s
4.Establish Storageclass Resource object ( sc): root@master yaml]# vim sc.yaml apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: sc-nfs namespace: lbs-test #Namespace name provisioner: lbs-test#Same value as env environment variable of deployment resource reclaimPolicy: Retain #Recycling Policy
Execute the yaml file and view the SC: br/>1.[root@master yaml]# kubectl apply -f sc.yaml
2.storageclass.storage.k8s.io/sc-nfs created br/>3.[root@master yaml]# kubectl get sc -n lbs-test
4.NAME PROVISIONER AGE
5.sc-nfs lbs-test 8s
5. Create StatefulSet resource object, automatically create PVC:
vim statefulset.yaml
apiVersion: v1
kind: Service
metadata:
name: headless-svc
namespace: lbs-test
labels:
app: headless-svc
spec:
ports:
- port: 80
name: myweb
selector:
app: headless-pod
clusterIP: None
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: statefulset-test
namespace: lbs-test
spec:
serviceName: headless-svc
replicas: 3
selector:
matchLabels:
app: headless-pod
template:
metadata:
labels:
app: headless-pod
spec:
containers:
- image: httpd
name: myhttpd
ports:
- containerPort: 80
name: httpd
volumeMounts:
- mountPath: /mnt
name: test
volumeClaimTemplates: This field: Auto-create PVC
- metadata:
name: test
annotations: //This is to specify the storageclass with the same name
volume.beta.kubernetes.io/storage-class: sc-nfs
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 100MiExecute the yaml file and view the Pod: br/>1.[root@master yaml]# kubectl apply -f statefulset.yaml
2.service/headless-svc created br/>3.statefulset.apps/statefulset-test created
4.[root@master yaml]# kubectl get pod -n lbs-test
5.NAME READY STATUS RESTARTS AGE
6.nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 22m
7.statefulset-test-0 1/1 Running 0 8m59s
8.statefulset-test-1 1/1 Running 0 2m30s
9.statefulset-test-2 1/1 Running 0 109s
**Check to see if auto-created PV and PVC** PV: 1.[root@master yaml]# kubectl get pv -n lbs-test 2.NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 3.pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5 100Mi RWO Delete Bound lbh-test/test-statefulset-test-2 sc-nfs 4m23s 4.pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5 100Mi RWO Delete Bound lbh-test/test-statefulset-test-0 sc-nfs 11m 5.pvc-99137753-ccd0-4524-bf40-f3576fc97eba 100Mi RWO Delete Bound lbh-test/test-statefulset-test-1 sc-nfs 5m4s PVC: 1.[root@master yaml]# kubectl get pvc -n lbs-test 2.NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE 3.test-statefulset-test-0 Bound pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5 100Mi RWO sc-nfs 13m 4.test-statefulset-test-1 Bound pvc-99137753-ccd0-4524-bf40-f3576fc97eba 100Mi RWO sc-nfs 6m42s 5.test-statefulset-test-2 Bound pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5 100Mi RWO sc-nfs 6m1s
See if you want to create a persistent directory:
1.[root@master yaml]# ls /nfsdata/
2.lbh-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5
3.lbh-test-test-statefulset-test-1-pvc-99137753-ccd0-4524-bf40-f3576fc97eba
4.lbh-test-test-statefulset-test-2-pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5
6. Create data within pod resources.And access the tests.
1.[root@master yaml]# cd /nfsdata/ 2.[root@master nfsdata]# echo 111 > lbs-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5/index.html 3.[root@master nfsdata]# echo 222 > lbs-test-test-statefulset-test-1-pvc-99137753-ccd0-4524-bf40-f3576fc97eba/index.html 4.[root@master nfsdata]# echo 333 > lbs-test-test-statefulset-test-2-pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5/index.html 5.[root@master nfsdata]# kubectl get pod -o wide -n lbs-test 6.NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES 7.nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 30m 10.244.2.2 node02 <none> <none> 8.statefulset-test-0 1/1 Running 0 17m 10.244.1.2 node01 <none> <none> 9.statefulset-test-1 1/1 Running 0 10m 10.244.2.3 node02 <none> <none> 10.statefulset-test-2 1/1 Running 0 9m57s 10.244.1.3 node01 <none> <none> 11.[root@master nfsdata]# curl 10.244.1.2 12.111 13.[root@master nfsdata]# curl 10.244.2.3 14.222 15.[root@master nfsdata]# curl 10.244.1.3 16.333
7.Delete one of them pod，View this pod Will the resource's data**Re-create and exist.** 1.[root@master ~]# kubectl get pod -n lbs-test 2.NAME READY STATUS RESTARTS AGE 3.nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 33m 4.statefulset-test-0 1/1 Running 0 20m 5.statefulset-test-1 1/1 Running 0 13m 6.statefulset-test-2 1/1 Running 0 13m 7.[root@master ~]# kubectl delete pod -n lbs-test statefulset-test-0 8.pod "statefulset-test-0" deleted **9. Deleted and recreated pod Resources** 10.[root@master ~]# kubectl get pod -n lbs-test -o wide 11.NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES 12.nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 35m 10.244.2.2 node02 <none> <none> 13.statefulset-test-0 1/1 Running 0 51s 10.244.1.4 node01 <none> <none> 14.statefulset-test-1 1/1 Running 0 15m 10.244.2.3 node02 <none> <none> 15.statefulset-test-2 1/1 Running 0 14m 10.244.1.3 node01 <none> <none> **The data still exists.** 16.[root@master ~]# curl 10.244.1.4 17.111 18.[root@master ~]# cat /nfsdata/lbs-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5/index.html 19.111
StatefulSet resource object, data persistence test for stateful services completed.
Testing has allowed access to previously persisted data even after the Pod is deleted and the schedule is regenerated.