pod控制器-Deployment

deployment并不直接管理pod,而是通过replicaSet来控制pod。
Deployment主要功能有下面几个:

  • 支持ReplicaSet的所有功能
  • 支持发布的停止、继续
  • 支持滚动升级和回滚版本
    Deployment的资源清单文件:
apiVersion: apps/v1 # 版本号
kind: Deployment # 类型       
metadata: # 元数据
  name: # rs名称 
  namespace: # 所属命名空间 
  labels: #标签
    controller: deploy
spec: # 详情描述
  replicas: 3 # 副本数量
  revisionHistoryLimit: 3 # 保留历史版本
  paused: false # 暂停部署,默认是false
  progressDeadlineSeconds: 600 # 部署超时时间(s),默认是600
  strategy: # 策略
    type: RollingUpdate # 滚动更新策略
    rollingUpdate: # 滚动更新
      maxSurge: 30% # 最大额外可以存在的副本数,可以为百分比,也可以为整数
      maxUnavailable: 30% # 最大不可用状态的 Pod 的最大值,可以为百分比,也可以为整数
  selector: # 选择器,通过它指定该控制器管理哪些pod
    matchLabels:      # Labels匹配规则
      app: nginx-pod
    matchExpressions: # Expressions匹配规则
      - {key: app, operator: In, values: [nginx-pod]}
  template: # 模板,当副本数量不足时,会根据下面的模板创建pod副本
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80

创建deployment

创建pc-deployment.yaml,内容如下:

apiVersion: apps/v1
kind: Deployment      
metadata:
  name: pc-deployment
  namespace: dev
spec: 
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
# 创建deployment
# --record是开启记录功能
[root@k8s-master01 ~]# kubectl create -f pc-deployment.yaml --record=true
deployment.apps/pc-deployment created

# 查看deployment
# UP-TO-DATE 最新版本的pod的数量
# AVAILABLE  当前可用的pod的数量
[root@k8s-master01 ~]# kubectl get deploy pc-deployment -n dev
NAME            READY   UP-TO-DATE   AVAILABLE   AGE
pc-deployment   3/3     3            3           15s

# 查看rs
# 发现rs的名称是在原来deployment的名字后面添加了一个10位数的随机串
[root@k8s-master01 ~]# kubectl get rs -n dev
NAME                       DESIRED   CURRENT   READY   AGE
pc-deployment-6696798b78   3         3         3       23s

# 查看pod
[root@k8s-master01 ~]# kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-6696798b78-d2c8n   1/1     Running   0          107s
pc-deployment-6696798b78-smpvp   1/1     Running   0          107s
pc-deployment-6696798b78-wvjd8   1/1     Running   0          107s

扩缩容

# 变更副本数量为5个
[root@k8s-master01 ~]# kubectl scale deploy pc-deployment --replicas=5  -n dev
deployment.apps/pc-deployment scaled

# 查看deployment
[root@k8s-master01 ~]# kubectl get deploy pc-deployment -n dev
NAME            READY   UP-TO-DATE   AVAILABLE   AGE
pc-deployment   5/5     5            5           2m

# 查看pod
[root@k8s-master01 ~]#  kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-6696798b78-d2c8n   1/1     Running   0          4m19s
pc-deployment-6696798b78-jxmdq   1/1     Running   0          94s
pc-deployment-6696798b78-mktqv   1/1     Running   0          93s
pc-deployment-6696798b78-smpvp   1/1     Running   0          4m19s
pc-deployment-6696798b78-wvjd8   1/1     Running   0          4m19s

# 编辑deployment的副本数量,修改spec:replicas: 4即可
[root@k8s-master01 ~]# kubectl edit deploy pc-deployment -n dev
deployment.apps/pc-deployment edited

# 查看pod
[root@k8s-master01 ~]# kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-6696798b78-d2c8n   1/1     Running   0          5m23s
pc-deployment-6696798b78-jxmdq   1/1     Running   0          2m38s
pc-deployment-6696798b78-smpvp   1/1     Running   0          5m23s
pc-deployment-6696798b78-wvjd8   1/1     Running   0          5m23s

镜像更新

如果我们需要更新我们的应用。那么我们此时就需要用到k8s的镜像更新。
deployment支持两种更新策略:重建更新滚动更新,可以通过strategy指定策略类型,支持两个属性:

strategy:指定新的Pod替换旧的Pod的策略, 支持两个属性:
  type:指定策略类型,支持两种策略
    Recreate:在创建出新的Pod之前会先杀掉所有已存在的Pod
    RollingUpdate:滚动更新,就是杀死一部分,就启动一部分,在更新过程中,存在两个版本Pod
  rollingUpdate:当type为RollingUpdate时生效,用于为RollingUpdate设置参数,支持两个属性:
    maxUnavailable:更新中可用的副本数(包含新旧副本),可以以数值或者百分比,假如定义的是3副本,maxUnavailable=1,3-1=2,默认为25%。
    maxSurge:更新中最高可以超出的副本总数(包含新旧副本),可以以数值或者百分比,假如定义的是3副本,maxSurge=1,3+1=4。默认为25%。
    
# maxSurge和maxUnavailbale可以为0,但是不能同时为0
# 滚动更新默认配置隐含的意思其实就是每次以四分之一进行更新交替新旧版本,这个最小化的实现平滑过度更新
重建更新
  1. 编辑pc-deployment.yaml,在spec节点下添加更新策略
apiVersion: apps/v1
kind: Deployment
metadata:
  name: pc-deployment
  namespace: dev
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
      strategy: # 策略
        type: Recreate # 重建更新
  1. 创建deploy进行验证
# 变更镜像
[root@k8s-master01 ~]# kubectl set image deployment pc-deployment nginx=nginx:1.17.2 -n dev
deployment.apps/pc-deployment image updated

# 观察升级过程
[root@k8s-master01 ~]# kubectl get pods -n dev -w
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-5d89bdfbf9-65qcw   1/1     Running   0          31s
pc-deployment-5d89bdfbf9-w5nzv   1/1     Running   0          31s
pc-deployment-5d89bdfbf9-xpt7w   1/1     Running   0          31s

pc-deployment-5d89bdfbf9-xpt7w   1/1     Terminating   0          41s
pc-deployment-5d89bdfbf9-65qcw   1/1     Terminating   0          41s
pc-deployment-5d89bdfbf9-w5nzv   1/1     Terminating   0          41s

pc-deployment-675d469f8b-grn8z   0/1     Pending       0          0s
pc-deployment-675d469f8b-hbl4v   0/1     Pending       0          0s
pc-deployment-675d469f8b-67nz2   0/1     Pending       0          0s

pc-deployment-675d469f8b-grn8z   0/1     ContainerCreating   0          0s
pc-deployment-675d469f8b-hbl4v   0/1     ContainerCreating   0          0s
pc-deployment-675d469f8b-67nz2   0/1     ContainerCreating   0          0s

pc-deployment-675d469f8b-grn8z   1/1     Running             0          1s
pc-deployment-675d469f8b-67nz2   1/1     Running             0          1s
pc-deployment-675d469f8b-hbl4v   1/1     Running             0          2s
滚动更新
  1. 编辑pc-deployment.yaml,在spec节点下添加更新策略
spec:
  strategy: # 策略
    type: RollingUpdate # 滚动更新策略
    rollingUpdate:
      maxSurge: 25% 
      maxUnavailable: 25%
  1. 创建deploy进行验证
# 变更镜像
[root@k8s-master01 ~]# kubectl set image deployment pc-deployment nginx=nginx:1.17.3 -n dev 
deployment.apps/pc-deployment image updated

# 观察升级过程
[root@k8s-master01 ~]# kubectl get pods -n dev -w
[root@k8s-master01 deployment]#  kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
nginx-cc7df4f8f-kcn4r            1/1     Running   0          7h9m
nginx-cc7df4f8f-krwk9            1/1     Running   0          7h9m
nginx-cc7df4f8f-vp6tc            1/1     Running   0          7h2m
pc-deployment-57df6f8b8c-5tzlk   1/1     Running   0          103s
pc-deployment-57df6f8b8c-vdgp6   1/1     Running   0          2m52s
pc-deployment-57df6f8b8c-vfbm9   1/1     Running   0          117s
pc-deployment-57df6f8b8c-xtns8   1/1     Running   0          2m52s
[root@k8s-master01 deployment]# kubectl describe pod pc-deployment-57df6f8b8c-5tzlk -n dev | grep Image
    Image:          nginx:1.17.3
    Image ID:       docker-pullable://nginx@sha256:9688d0dae8812dd2437947b756393eb0779487e361aa2ffbc3a529dca61f102c
[root@k8s-master01 deployment]# kubectl describe pod pc-deployment-57df6f8b8c-vdgp6 -n dev | grep Image
    Image:          nginx:1.17.3
    Image ID:       docker-pullable://nginx@sha256:9688d0dae8812dd2437947b756393eb0779487e361aa2ffbc3a529dca61f102c
[root@k8s-master01 deployment]# kubectl describe pod pc-deployment-57df6f8b8c-vfbm9 -n dev | grep Image
    Image:          nginx:1.17.3
    Image ID:       docker-pullable://nginx@sha256:9688d0dae8812dd2437947b756393eb0779487e361aa2ffbc3a529dca61f102c
[root@k8s-master01 deployment]# kubectl describe pod pc-deployment-57df6f8b8c-xtns8 -n dev | grep Image
    Image:          nginx:1.17.3
    Image ID:       docker-pullable://nginx@sha256:9688d0dae8812dd2437947b756393eb0779487e361aa2ffbc3a529dca61f102c
[root@k8s-master01 deployment]#

# 至此,新版本的pod创建完毕,就版本的pod销毁完毕
# 中间过程是滚动进行的,也就是边销毁边创建

版本回退

deployment支持版本升级过程中的暂停、继续功能以及版本回退等诸多功能,下面具体来看.

kubectl rollout: 版本升级相关功能,支持下面的选项:

  • status 显示当前升级状态
  • history 显示 升级历史记录
  • pause 暂停版本升级过程
  • resume 继续已经暂停的版本升级过程
  • restart 重启版本升级过程
  • undo 回滚到上一级版本(可以使用–to-revision回滚到指定版本)
# 现在的nginx是1.17.3,我们回滚到最初的1.17.1
[root@k8s-master01 deployment]# kubectl rollout undo deployment pc-deployment --to-revision 1 -n dev
deployment.apps/pc-deployment rolled back
[root@k8s-master01 deployment]# kubectl get pod -n dev
NAME                             READY   STATUS    RESTARTS   AGE
nginx-cc7df4f8f-kcn4r            1/1     Running   0          7h30m
nginx-cc7df4f8f-krwk9            1/1     Running   0          7h30m
nginx-cc7df4f8f-vp6tc            1/1     Running   0          7h23m
pc-deployment-858db84f89-7666w   1/1     Running   0          11s
pc-deployment-858db84f89-bptsc   1/1     Running   0          10s
pc-deployment-858db84f89-bxr29   1/1     Running   0          11s
pc-deployment-858db84f89-zmvxm   1/1     Running   0          9s
[root@k8s-master01 deployment]# kubectl describe pod pc-deployment-858db84f89-7666w -n dev | grep Image
    Image:          nginx:1.17.1
    Image ID:       docker-pullable://nginx@sha256:b4b9b3eee194703fc2fa8afa5b7510c77ae70cfba567af1376a573a967c03dbb
[root@k8s-master01 deployment]#

金丝雀发布

Deployment控制器支持控制更新过程中的控制,如“暂停(pause)”或“继续(resume)”更新操作。

比如有一批新的Pod资源创建完成后立即暂停更新过程,此时,仅存在一部分新版本的应用,主体部分还是旧的版本。然后,再筛选一小部分的用户请求路由到新版本的Pod应用,继续观察能否稳定地按期望的方式运行。确定没问题之后再继续完成余下的Pod资源滚动更新,否则立即回滚更新操作。这就是所谓的金丝雀发布。

# 更新deployment的版本,并配置暂停deployment
[root@k8s-master01 ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.4 -n dev && kubectl rollout pause deployment pc-deployment  -n dev
deployment.apps/pc-deployment image updated
deployment.apps/pc-deployment paused

#观察更新状态
[root@k8s-master01 ~]# kubectl rollout status deploy pc-deployment -n dev 
Waiting for deployment "pc-deployment" rollout to finish: 2 out of 4 new replicas have been updated...

# 监控更新的过程,可以看到已经新增了一个资源,但是并未按照预期的状态去删除一个旧的资源,就是因为使用了pause暂停命令

[root@k8s-master01 ~]# kubectl get rs -n dev -o wide
NAME                       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES         
pc-deployment-5d89bdfbf9   3         3         3       19m     nginx        nginx:1.17.1   
pc-deployment-675d469f8b   0         0         0       14m     nginx        nginx:1.17.2   
pc-deployment-6c9f56fcfb   2         2         2       3m16s   nginx        nginx:1.17.4   
[root@k8s-master01 ~]# kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-5d89bdfbf9-rj8sq   1/1     Running   0          7m33s
pc-deployment-5d89bdfbf9-ttwgg   1/1     Running   0          7m35s
pc-deployment-5d89bdfbf9-v4wvc   1/1     Running   0          7m34s
pc-deployment-6c9f56fcfb-996rt   1/1     Running   0          3m31s
pc-deployment-6c9f56fcfb-j2gtj   1/1     Running   0          3m31s

# 确保更新的pod没问题了,继续更新
[root@k8s-master01 ~]# kubectl rollout resume deploy pc-deployment -n dev
deployment.apps/pc-deployment resumed

# 查看最后的更新情况
[root@k8s-master01 ~]# kubectl get rs -n dev -o wide
NAME                       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES         
pc-deployment-5d89bdfbf9   0         0         0       21m     nginx        nginx:1.17.1   
pc-deployment-675d469f8b   0         0         0       16m     nginx        nginx:1.17.2   
pc-deployment-6c9f56fcfb   4         4         4       5m11s   nginx        nginx:1.17.4   

[root@k8s-master01 ~]# kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-6c9f56fcfb-7bfwh   1/1     Running   0          37s
pc-deployment-6c9f56fcfb-996rt   1/1     Running   0          5m27s
pc-deployment-6c9f56fcfb-j2gtj   1/1     Running   0          5m27s
pc-deployment-6c9f56fcfb-rf84v   1/1     Running   0          37s

删除Deployment

# 删除deployment,其下的rs和pod也将被删除
[root@k8s-master01 ~]# kubectl delete -f pc-deployment.yaml
deployment.apps "pc-deployment" deleted
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