- 声明式配置文件：要求集群中的某一个资源，处于指定的状态。
- 集群中都有哪些可以管理的资源？
- 控制器： 用来控制pod数量、运行参数
- deployment 管理灵活，而pod的创建、删除、运行、更新等均无需直接操作pod，只需要更新deployment的配置
1.如何控制pod
deployment ----> replica set (基于template 运行的pod的数量)---> 创建服务需要的pod
[root@control ~]# cat nginx-deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:name: nginx-deployment
spec:selector:matchLabels:app: nginxreplicas: 3template:metadata:labels:app: nginxspec:containers:- name: nginximage: nginx:latestimagePullPolicy: IfNotPresentports:- containerPort: 80[root@control ~]# source .kube/k8s_bash_completion
[root@control ~]# kubectl create -f nginx-deployment.yml
deployment.apps/nginx-deployment created
[root@control ~]# kubectl get deployments.apps -l app=nginx
No resources found in default namespace.
[root@control ~]# kubectl get deployments.apps
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx 2/2 2 2 3d21h
nginx-deployment 3/3 3 3 29s
[root@control ~]# kubectl describe deployments.apps nginx-deployment
Name: nginx-deployment
Namespace: default
CreationTimestamp: Tue, 24 Sep 2024 14:27:32 +0800
Labels: <none>
Annotations: deployment.kubernetes.io/revision: 1
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:Labels: app=nginxContainers:nginx:Image: nginx:latestPort: 80/TCPHost Port: 0/TCPEnvironment: <none>Mounts: <none>Volumes: <none>Node-Selectors: <none>Tolerations: <none>
Conditions:Type Status Reason---- ------ ------Available True MinimumReplicasAvailableProgressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deployment-bf56f49c (3/3 replicas created)
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal ScalingReplicaSet 85s deployment-controller Scaled up replica set nginx-deployment-bf56f49c to 3
[root@control ~]# kubectl get rs nginx-deployment-bf56f49c
NAME DESIRED CURRENT READY AGE
nginx-deployment-bf56f49c 3 3 3 2m22s
[root@control ~]# kubectl get pods -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-deployment-bf56f49c-9c8gw 1/1 Running 0 6m48s
nginx-deployment-bf56f49c-n59hg 1/1 Running 0 6m48s
nginx-deployment-bf56f49c-v887p 1/1 Running 0 6m48s
[root@control ~]# kubectl get pods -l app=nginx --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-deployment-bf56f49c-9c8gw 1/1 Running 0 7m32s app=nginx,pod-template-hash=bf56f49c
nginx-deployment-bf56f49c-n59hg 1/1 Running 0 7m32s app=nginx,pod-template-hash=bf56f49c
nginx-deployment-bf56f49c-v887p 1/1 Running 0 7m32s app=nginx,pod-template-hash=bf56f49c
//为了保证工作节点有，需要更新的镜像，手动上传镜像到工作节点
[root@control ~]# docker save -o nginx-19.1.tar nginx:1.19.1
[root@control ~]# scp nginx-19.1.tar root@node1:/root
root@node1's password:
nginx-19.1.tar 0% 0 0nginx-19.1.tar 40% 52MB 52nginx-19.1.tar 100% 130MB 47
[root@control ~]# scp nginx-19.1.tar root@node2:/root
root@node2's password:
nginx-19.1.tar 100% 130MB 51.7MB/s 00:02
[root@node1 ~]# ctr -n k8s.io image import nginx-19.1.tar
[root@node2 ~]# ctr -n k8s.io image import nginx-19.1.tar
// 查看工作节点保存的镜像
[root@node2 ~]# crictl -r unix:///var/run/containerd/containerd.sock images返回控制节点，进行更新操作
// 更新镜像
[root@control ~]# kubectl set image deployments nginx-deployment nginx=nginx:1.19.1
deployment.apps/nginx-deployment image updated
[root@control ~]# kubectl get pods -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-deployment-7f588fbd68-bjd67 1/1 Running 0 9s
nginx-deployment-7f588fbd68-n2fls 1/1 Running 0 5s
nginx-deployment-7f588fbd68-qnwdn 1/1 Running 0 8s
[root@control ~]# kubectl describe deployments.apps nginx-deployment
Name: nginx-deployment
Namespace: default
CreationTimestamp: Tue, 24 Sep 2024 14:27:32 +0800
Labels: <none>
Annotations: deployment.kubernetes.io/revision: 2
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:Labels: app=nginxContainers:nginx:Image: nginx:1.19.1Port: 80/TCPHost Port: 0/TCPEnvironment: <none>Mounts: <none>Volumes: <none>Node-Selectors: <none>Tolerations: <none>
Conditions:Type Status Reason---- ------ ------Available True MinimumReplicasAvailableProgressing True NewReplicaSetAvailable
OldReplicaSets: nginx-deployment-bf56f49c (0/0 replicas created)
NewReplicaSet: nginx-deployment-7f588fbd68 (3/3 replicas created)
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal ScalingReplicaSet 15m deployment-controller Scaled up replica set nginx-deployment-bf56f49c to 3Normal ScalingReplicaSet 49s deployment-controller Scaled up replica set nginx-deployment-7f588fbd68 to 1Normal ScalingReplicaSet 48s deployment-controller Scaled down replica set nginx-deployment-bf56f49c to 2 from 3Normal ScalingReplicaSet 48s deployment-controller Scaled up replica set nginx-deployment-7f588fbd68 to 2 from 1Normal ScalingReplicaSet 45s deployment-controller Scaled down replica set nginx-deployment-bf56f49c to 1 from 2Normal ScalingReplicaSet 45s deployment-controller Scaled up replica set nginx-deployment-7f588fbd68 to 3 from 2Normal ScalingReplicaSet 44s deployment-controller Scaled down replica set nginx-deployment-bf56f49c to 0 from 1
// deployment 更新后创建新的rs来启动新的容器，并保留原本的rs
// rs 一般只保留两个，除非额外配置
[root@control ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
my-nginx-7549dd6888 2 2 2 3d21h
nginx-deployment-7f588fbd68 3 3 3 2m18s
nginx-deployment-bf56f49c 0 0 0 16m
[root@control ~]# kubectl edit deployments.apps nginx-deployment
deployment.apps/nginx-deployment edited
// 展示更新过程
// 失败的原因是无法拉取nginx 1.191 镜像
[root@control ~]# kubectl rollout status deployment nginx-deployment
Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
^C
[root@control ~]# kubectl get pods -l app=nginx// 一个pod 状态错误 三个pod状态正常
NAME READY STATUS RESTARTS AGE
nginx-deployment-6dc44567c6-85glr 0/1 ImagePullBackOff 0 54s
nginx-deployment-7f588fbd68-bjd67 1/1 Running 0 8m58s
nginx-deployment-7f588fbd68-n2fls 1/1 Running 0 8m54s
nginx-deployment-7f588fbd68-qnwdn 1/1 Running 0 8m57s
[root@control ~]# kubectl get deployments.apps nginx-deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 1 3 23m
// 查看更新历史
[root@control ~]# kubectl rollout history deployment nginx-deployment
deployment.apps/nginx-deployment
REVISION CHANGE-CAUSE
1 <none>
2 <none>
3 <none>// 查看第二次更新的参数
[root@control ~]# kubectl rollout history deployment nginx-deployment --revision=2
deployment.apps/nginx-deployment with revision #2
Pod Template:Labels: app=nginxpod-template-hash=7f588fbd68Containers:nginx:Image: nginx:1.19.1Port: 80/TCPHost Port: 0/TCPEnvironment: <none>Mounts: <none>Volumes: <none>Node-Selectors: <none>Tolerations: <none>// 回滚失败的更新
[root@control ~]# kubectl rollout undo deployment nginx-deployment
deployment.apps/nginx-deployment rolled back
[root@control ~]# kubectl get deployments.apps nginx-deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 27m
deployment 是最常见的无状态服务部署方式，常见的用例包括：
- 使用 Deployment 来创建 ReplicaSet。ReplicaSet 在后台创建 pod。检查启动状态，看它是成功还是失败。
- 然后，通过更新 Deployment 的 PodTemplateSpec 字段来声明 Pod 的新状态。这会创建一个新的 ReplicaSet，Deployment 会按照控制的速率将 pod 从旧的 ReplicaSet 移动到新的 ReplicaSet 中。
- 如果当前状态不稳定，回滚到之前的 Deployment revision。每次回滚都会更新 Deployment 的 revision。
- 扩容 Deployment 以满足更高的负载。
- 暂停 Deployment 来应用 PodTemplateSpec 的多个修复，然后恢复上线。
- 根据 Deployment 的状态判断上线是否 hang 住了。
- 清除旧的不必要的 ReplicaSet。
无状态服务和有状态服务最直接的区别就是：
- pod是否需要分配固定的存储
- pod是否需要固定的网络参数
- pod 启动顺序是否有序
对于有状态服务，一般使用statefulSet来实现，常见用例：
- 稳定的持久化存储，即 Pod 重新调度后还是能访问到相同的持久化数据，基于 PVC 来实现，eg: 关系型数据库
- 稳定的网络标志，即 Pod 重新调度后其 PodName 和 HostName 不变，基于 Headless Service（即没有 Cluster IP 的 Service）来实现
- 有序部署，有序扩展，即 Pod 是有顺序的，在部署或者扩展的时候要依据定义的顺序依次依次进行（即从 0 到 N-1，在下一个 Pod 运行之前所有之前的 Pod 必须都是 Running 和 Ready 状态），基于 init containers 来实现
- 有序收缩，有序删除（即从 N-1 到 0）
使用nginx 作为反向代理 // 无状态服务 不涉及任何真实应用数据
使用lnmp架构运行web应用 // 有状态服务 与应用代码，且数据库保存应用数据，因此数据一定需要进行持久化
使用nginx 作为statefulset的练习：
[root@control ~]# cat nginx-stateful.yml
apiVersion: v1
kind: Service
metadata:name: nginxlabels:app: nginx
spec:ports:- port: 80name: webclusterIP: Noneselector:app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:name: web
spec:serviceName: "nginx"replicas: 2selector:matchLabels:app: nginxtemplate:metadata:labels:app: nginxspec:containers:- name: nginximage: nginx:1.19.1imagePullPolicy: IfNotPresentports:- containerPort: 80name: webvolumeMounts:- name: wwwmountPath: /usr/share/nginx/htmlvolumeClaimTemplates:- metadata:name: wwwspec:storageClassName: local-storageaccessModes: [ "ReadWriteOnce" ]resources:requests:storage: 4Gi[root@control ~]# cat pv-1.yml
apiVersion: v1
kind: PersistentVolume
metadata:name: example-pv
spec:capacity:storage: 4GivolumeMode: FilesystemaccessModes:- ReadWriteOncepersistentVolumeReclaimPolicy: DeletestorageClassName: local-storagelocal:path: /mnt/lv/swapnodeAffinity:required:nodeSelectorTerms:- matchExpressions:- key: kubernetes.io/hostnameoperator: Invalues:- node1
[root@control ~]# cat pv-2.yml
apiVersion: v1
kind: PersistentVolume
metadata:name: example-pv2
spec:capacity:storage: 4GivolumeMode: FilesystemaccessModes:- ReadWriteOncepersistentVolumeReclaimPolicy: DeletestorageClassName: local-storagelocal:path: /mnt/lv/swapnodeAffinity:required:nodeSelectorTerms:- matchExpressions:- key: kubernetes.io/hostnameoperator: Invalues:- node2
[root@control ~]# cat local_storage.yml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:name: local-storage
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
[root@control ~]# kubectl create -f local_storage.yml
storageclass.storage.k8s.io/local-storage created
[root@control ~]# kubectl get storageclasses.storage.k8s.io
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
local-storage kubernetes.io/no-provisioner Delete WaitForFirstConsumer false 2snode1 he node2
[root@node1 ~]# mkfs.xfs -f /dev/cs_bogon/swap
meta-data=/dev/cs_bogon/swap isize=512 agcount=4, agsize=256768 blks= sectsz=512 attr=2, projid32bit=1= crc=1 finobt=1, sparse=1, rmapbt=0= reflink=1 bigtime=1 inobtcount=1 nrext64=0
data = bsize=4096 blocks=1027072, imaxpct=25= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=16384, version=2= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@node1 ~]# mkdir /mnt/lv/swap -p
[root@node1 ~]# mount /dev/cs_bogon/swap /mnt/lv/swap/返回控制节点：
创建持久卷
[root@control ~]# kubectl create -f pv-1.yml
persistentvolume/example-pv created
[root@control ~]# kubectl create -f pv-2.yml
Error from server (AlreadyExists): error when creating "pv-2.yml": persistentvolumes "example-pv" already exists
[root@control ~]# vim pv-2.yml
[root@control ~]# kubectl create -f pv-2.yml
persistentvolume/example-pv2 created
[root@control ~]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS VOLUMEATTRIBUTESCLASS REASON AGE
example-pv 4Gi RWO Delete Available local-storage <unset> 25s
example-pv2 4Gi RWO Delete Available local-storage <unset> 6s
[root@control ~]# kubectl apply -f nginx-stateful.yml
service/nginx created
statefulset.apps/web created
[root@control ~]# kubectl get statefulsets.apps
NAME READY AGE
web 2/2 7s
[root@control ~]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS VOLUMEATTRIBUTESCLASS AGE
www-web-0 Bound example-pv 4Gi RWO local-storage <unset> 16s
www-web-1 Bound example-pv2 4Gi RWO local-storage <unset> 14s
[root@control ~]# kubectl describe statefulsets.apps web
Name: web
Namespace: default
CreationTimestamp: Tue, 24 Sep 2024 17:18:48 +0800
Selector: app=nginx
Labels: <none>
Annotations: <none>
Replicas: 2 desired | 2 total
Update Strategy: RollingUpdatePartition: 0
Pods Status: 2 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:Labels: app=nginxContainers:nginx:Image: nginx:1.19.1Port: 80/TCPHost Port: 0/TCPEnvironment: <none>Mounts:/usr/share/nginx/html from www (rw)Volumes: <none>Node-Selectors: <none>Tolerations: <none>
Volume Claims:Name: wwwStorageClass: local-storageLabels: <none>Annotations: <none>Capacity: 4GiAccess Modes: [ReadWriteOnce]
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal SuccessfulCreate 55s statefulset-controller create Claim www-web-0 Pod web-0 in StatefulSet web successNormal SuccessfulCreate 55s statefulset-controller create Pod web-0 in StatefulSet web successfulNormal SuccessfulCreate 53s statefulset-controller create Claim www-web-1 Pod web-1 in StatefulSet web successNormal SuccessfulCreate 53s statefulset-controller create Pod web-1 in StatefulSet web successful
[root@control ~]# kubectl get pods --watch -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-deployment-7f588fbd68-bjd67 1/1 Running 0 160m
nginx-deployment-7f588fbd68-n2fls 1/1 Running 0 160m
nginx-deployment-7f588fbd68-qnwdn 1/1 Running 0 160m
web-0 1/1 Running 0 3m15s
web-1 1/1 Running 0 3m13s
^C[root@control ~]# kubectl delete pod -l app=nginx
pod "nginx-deployment-7f588fbd68-bjd67" deleted
pod "nginx-deployment-7f588fbd68-n2fls" deleted
pod "nginx-deployment-7f588fbd68-qnwdn" deleted
pod "web-0" deleted
pod "web-1" deleted[root@control ~]#
[root@control ~]# kubectl get statefulsets.apps
NAME READY AGE
web 2/2 4m43s
[root@control ~]# kubectl get pods -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-deployment-7f588fbd68-4lrb5 1/1 Running 0 36s
nginx-deployment-7f588fbd68-8jnm5 1/1 Running 0 36s
nginx-deployment-7f588fbd68-mvgzg 1/1 Running 0 36s
web-0 1/1 Running 0 35s
web-1 1/1 Running 0 33s
[root@control ~]# kubectl describe statefulsets.apps web
Name: web
Namespace: default
CreationTimestamp: Tue, 24 Sep 2024 17:18:48 +0800
Selector: app=nginx
Labels: <none>
Annotations: <none>
Replicas: 2 desired | 2 total
Update Strategy: RollingUpdatePartition: 0
Pods Status: 2 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:Labels: app=nginxContainers:nginx:Image: nginx:1.19.1Port: 80/TCPHost Port: 0/TCPEnvironment: <none>Mounts:/usr/share/nginx/html from www (rw)Volumes: <none>Node-Selectors: <none>Tolerations: <none>
Volume Claims:Name: wwwStorageClass: local-storageLabels: <none>Annotations: <none>Capacity: 4GiAccess Modes: [ReadWriteOnce]
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal SuccessfulCreate 5m16s statefulset-controller create Claim www-web-0 Pod web-0 in StatefulSet web successNormal SuccessfulCreate 5m14s statefulset-controller create Claim www-web-1 Pod web-1 in StatefulSet web successNormal SuccessfulCreate 48s (x2 over 5m16s) statefulset-controller create Pod web-0 in StatefulSet web successfulNormal SuccessfulCreate 46s (x2 over 5m14s) statefulset-controller create Pod web-1 in StatefulSet web successful
[root@control ~]# for i in 0 1; do kubectl exec web-$i -- sh -c 'hostname'; done
web-0
web-1结论：pod名称和持久卷的绑定都不会发生改变，因此可以实现数据和通信（无论pod如何变更，可以基于pod的名称进行通信）的固定。