Why k8s pv and not binding on PVC
Use statefuset deployed stateful applications, and applications are always pending state, before starting to explain what statefuset, in k8s in general management with deployment stateless applications, statefuset for managing stateful applications, such as redis, mysql, zookper distribution, etc. applications, these applications start to stop, there will be a strict order
A, statefulset
headless (headless service), no cluserIP, resource identifier, for generating a recording resolvable dns
Resource management StatefulSet for pod
volumeClaimTemplates provide storage
Two, statefulset deployment
Nfs make use of network storage
Build nfs
Configure shared storage directory
Creating pv
Choreography yaml
Build nfs
yum install nfs-utils -y
mkdir -p /usr/local/k8s/redis/pv{7..12} # create a mount directory
cat /etc/exports /usr/local/k8s/redis/pv7 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv8 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv9 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv10 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv11 172.16.0.0/16(rw,sync,no_root_squash exportfs -avr
Creating pv
cat nfs_pv2.yaml
apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv7 spec: capacity: storage: 500M accessModes: - ReadWriteMany persistentVolumeReclaimPolicy: Retain storageClassName: slow nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv7" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv8 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv8" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv9 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv9" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv10 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv10" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv11 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv11" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv12 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv12"
kubectl apply f nfs_pv2.yaml
View # successfully created
Scheduling application written 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 resources: requests: cpu: "500m" memory: "500Mi" ports: - containerPort: 80 name: web volumeMounts: - name: myappdata mountPath: /usr/share/nginx/html volumeClaimTemplates: - metadata: name: myappdata spec: accessModes: ["ReadWriteOnce"] storageClassName: "slow" resources: requests: storage: 400Mi
kubectl create -f new-stateful.yaml
View headless successfully created
View pod is successfully created
Check whether to create a successful pvc
pod start without success, depends on pvc, pvc log view, corresponding pvc is not found, clearly written ah
View related information, has the following attributes
storageClassName: "slow"
Three, statefulset troubleshooting
pvc can not be created, resulting in pod does not start normally, yaml file re-examined several times,
For thought: pvc how to bind pv, go through association storageClassName, pv create successful, there storageClassName: slow this attribute, the results stunned not find
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Pv and pvc back to check whether permission has been
Pv set of permissions found
pvc declaration of competence: volumeClaimTemplates
Permissions are inconsistent on both sides,
operating
Delete pvc kubectl delete pvc myappdata-myapp-0 -n daemon
Yaml delete files, kubectl delete -f new-stateful.yaml -n daemon
Try to modify accessModes: [ "ReadWriteMany"]
Check again
Tip: pv and PVC set permissions Notes
Four, statefulset test, DNS
kubectl exec -it myapp-0 sh -n daemon
nslookup myapp-0.myapp.daemon.svc.cluster.local
Rules resolved as follows
myapp-0 myapp daemon
FQDN： $(podname).(headless server name).namespace.svc.cluster.local
As there is no container nsllokup, to install the corresponding packet, busybox may provide similar functionality
Provided yaml file
apiVersion: v1 kind: Pod metadata: name: busybox namespace: daemon spec: containers: - name: busybox image: busybox:1.28.4 command: - sleep - "7600" resources: requests: memory: "200Mi" cpu: "250m" imagePullPolicy: IfNotPresent restartPolicy: Never
五、statefulset 的扩缩容
扩容：
Statefulset 资源的扩缩容与Deployment 资源相似，即通过修改副本数,Statefulset 资源的拓展过程，与创建过程类似，应用名称的索引号，依次增加
可使用 kubectl scale
kubectl patch
实践：kubectl scale statefulset myapp --replicas=4
缩容：
缩容只需要将pod 副本数调小
kubectl patch statefulset myapp -p '{"spec":{"replicas":3}}' -n daemon
Tip: resource scaling capacity, we need to dynamically create a binding relationship with pv pvc, where use is made nfs persistent storage, pv how much is pre-created
Sixth, rolling statefulset update
Rolling updates
Canary released
Rolling updates
Rollover is the beginning of the index from the largest pod number, complete termination of a resource, start making the next pod, rollover is statefulset default updating policy
kubectl set image statefulset/myapp myapp=ikubernetes/myapp:v2 -n daemon
The upgrade process
View pod status
kubectl get pods -n daemon
After a review of whether to update the upgrade image
kubectl describe pod myapp-0 -n daemon
