Kubernetes之Deployment控制器

Deployment 简介

deployment 是用来管理无状态应用的，面向的集群的管理，而不是面向的是一个不可变的个体，举例：有一群鸭子，要吃掉一个，只需要再放一个新的鸭仔就好了，不会影响什么，而有状态的应用，就同时养三条狗一样，而每个狗都是无法代替用新的事物代替的，因为有“感情”这个状态在里面。

Deployment 为Pod 和 ReplicaSet 之上，提供了一个声明式定义（declarative）方法，用来替代以前的ReplicationController 来方便的管理应用。

你只需要在 Deployment 中描述您想要的目标状态是什么，Deployment controller 就会帮您将 Pod 和ReplicaSet 的实际状态改变到您的目标状态。您可以定义一个全新的 Deployment 来

创建 ReplicaSet 或者删除已有的 Deployment 并创建一个新的来替换。也就是说Deployment是可以管理多个ReplicaSet的，如下图：

典型的应用场景包括：

• 定义Deployment来创建Pod和ReplicaSet,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d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。

Deployment 升级

kubectl explain deploy.spec.strategy   策略订是配置怎么滚动升级的，支持两种策略：

• Recreate   重建式更新，就是删一个建一个。
• rollingUpdate  滚动更新，简单定义 更新期间pod最多有几个等

rollingUpdate 有两种策略

• maxSurge  指定超出副本数有几个，两种方式：1、指定数量 2、百分比
• maxUnavailable 最多有几个不可用

Deployment 历史版本

kubectl explain deploy.spec.revisionHistoryLimit

最多保存多少个历史版本，默认是10个

Deployment 模板

kubectl explain deploy.spec.template

通过template 创建我们的目标状态

类似pod的定义（包含 spec 、 metadata）

   spec <Object>
     Specification of the desired behavior of the pod. More info: https://
     git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status/

   metadata     <Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata

案例：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas:
  selector:
    matchLabels:
      app: myapp
      release: dev
  template:
    metadata:
      labels:
        app: myapp
        release: dev
    spec:
      containers:
      - name: myapp-containers
        image: ikubernetes/myapp:v1
        ports:
        - name: http
          containerPort: 

结果

看一下deploy 是否成功
$ kubectl get deploy
NAME           DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
myapp-deploy                                            2m
因为deploy 是三层架构 现在会自动启动一个replicasets 我们看一下是否启动
$  kubectl get rs
NAME                     DESIRED   CURRENT   READY     AGE
myapp-deploy-f4bcc4799                              5m
我们看自动创建一个rs.名称后面的字符串是 模板的哈希值。是不会发生变化的，最后pod的是随机值

我们再看一下最后一层，最后一层为pod
$ kubectl get pods
NAME                           READY     STATUS    RESTARTS   AGE
myapp-deploy-f4bcc4799-cs5xc   /       Running             7m
myapp-deploy-f4bcc4799-k4tq5   /       Running             7m

滚动升级案例：

我们通过修改yaml的方式升级

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas:
  selector:
    matchLabels:
      app: myapp
      release: dev
  template:
    metadata:
      labels:
        app: myapp
        release: dev
    spec:
      containers:
      - name: myapp-containers
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 

升级过程(我们看到，是停止一台，升级一台的这种循环。)

kubectl get pods -l app=myapp -w
NAME                           READY     STATUS    RESTARTS   AGE
myapp-deploy-f4bcc4799-cs5xc   /       Running             23m
myapp-deploy-f4bcc4799-cwzd9   /       Running            14m
myapp-deploy-f4bcc4799-k4tq5   /       Running            23m
myapp-deploy-f4bcc4799-shbmb   /       Running            14m
myapp-deploy-f4bcc4799-vtk6m   /       Running            14m

myapp-deploy-f4bcc4799-shbmb   /       Terminating            16m
myapp-deploy-869b888f66-mv5c6   /       Pending            0s
myapp-deploy-869b888f66-mv5c6   /       Pending            0s
myapp-deploy-869b888f66-vk9j6   /       Pending            0s
myapp-deploy-869b888f66-vk9j6   /       Pending            0s
myapp-deploy-869b888f66-mv5c6   /       ContainerCreating            0s
myapp-deploy-869b888f66-r57t5   /       Pending            0s
myapp-deploy-869b888f66-r57t5   /       Pending            0s
myapp-deploy-869b888f66-vk9j6   /       ContainerCreating            1s
myapp-deploy-869b888f66-r57t5   /       ContainerCreating            1s
myapp-deploy-869b888f66-r57t5   /       ContainerCreating            1s
myapp-deploy-869b888f66-mv5c6   /       ContainerCreating            1s
myapp-deploy-869b888f66-vk9j6   /       ContainerCreating            2s
myapp-deploy-f4bcc4799-shbmb   /       Terminating            16m
myapp-deploy-f4bcc4799-shbmb   /       Terminating            16m
myapp-deploy-869b888f66-r57t5   /       Running            4s
myapp-deploy-f4bcc4799-vtk6m   /       Terminating            16m
myapp-deploy-869b888f66-rxzbb   /       Pending            1s
myapp-deploy-869b888f66-rxzbb   /       Pending            1s
myapp-deploy-869b888f66-rxzbb   /       ContainerCreating            1s
myapp-deploy-869b888f66-vk9j6   /       Running            5s
myapp-deploy-f4bcc4799-cwzd9   /       Terminating            16m
myapp-deploy-869b888f66-vvwwv   /       Pending            0s
myapp-deploy-869b888f66-vvwwv   /       Pending            0s
.....

我们查看一下 rs的情况 以下可以看到原的rs作为备份，而现在是启动新的rs

$  kubectl get rs -o wide
NAME                      DESIRED   CURRENT   READY     AGE       CONTAINER(S)       IMAGE(S)               SELECTOR
myapp-deploy-869b888f66                              3m        myapp-containers   ikubernetes/myapp:v2   app=myapp,pod-template-hash=,release=dev
myapp-deploy-f4bcc4799                               29m       myapp-containers   ikubernetes/myapp:v1   app=myapp,pod-template-hash=,release=dev

修改滚动升级策略

$ kubectl patch deplop  myapp-deploy -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":,"maxUnavailable":}}}}'
$  kubectl describe deploy  myapp-deploy 
Name:            myapp-deploy
Namespace:        default
CreationTimestamp:    Tue, 28 Aug 2018 09:52:03 -0400
Labels:            app=myapp
            release=dev
Annotations:        deployment.kubernetes.io/revision=4
            kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"name":"myapp-deploy","namespace":"default"},"spec":{"replicas":3,"selector":{...
Selector:        app=myapp,release=dev
Replicas:        3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:        RollingUpdate
MinReadySeconds:    0
RollingUpdateStrategy:    0 max unavailable, 1 max surge
Pod Template:
....

金丝雀发布

##通过 set image 发布新的镜像 也可以通过yaml文件发布 myapp-containers 是containers 的名称
$ kubectl set image deploy  myapp-deploy myapp-containers=ikubernetes/myapp:v3 && kubectl rollout pause deploy  myapp-deploy
deployment "myapp-deploy" image updated
deployment "myapp-deploy" paused

#查看更新情况(新增加一个资源，但是没执行。是因为pause暂停命令，所以发布一个，这样形成了金丝雀发布，这个金丝雀就是让真实用户验证的)
$ kubectl get pods -l  app=myapp -w
NAME                            READY     STATUS    RESTARTS   AGE
myapp-deploy-869b888f66-dpwvk   /       Running             24m
myapp-deploy-869b888f66-frspv   /       Running            24m
myapp-deploy-869b888f66-sgsll   /       Running            24m
myapp-deploy-7cbd5b69b9-5s4sq   /       Pending            0s
myapp-deploy-7cbd5b69b9-5s4sq   /       Pending            0s
myapp-deploy-7cbd5b69b9-5s4sq   /       ContainerCreating            1s
myapp-deploy-7cbd5b69b9-5s4sq   /       ContainerCreating            2s
myapp-deploy-7cbd5b69b9-5s4sq   /       Running            19s

#那个金丝雀没问题，可以发布后续的更新了
kubectl rollout resume deploy  myapp-deploy

#查看更新情况
 kubectl get pods -l  app=myapp -w
NAME                            READY     STATUS    RESTARTS   AGE
myapp-deploy-869b888f66-dpwvk   /       Running             24m
myapp-deploy-869b888f66-frspv   /       Running            24m
myapp-deploy-869b888f66-sgsll   /       Running            24m
myapp-deploy-7cbd5b69b9-5s4sq   /       Pending            0s
myapp-deploy-7cbd5b69b9-5s4sq   /       Pending            0s
myapp-deploy-7cbd5b69b9-5s4sq   /       ContainerCreating            1s
myapp-deploy-7cbd5b69b9-5s4sq   /       ContainerCreating            2s
myapp-deploy-7cbd5b69b9-5s4sq   /       Running            19s
myapp-deploy-869b888f66-dpwvk   /       Terminating            31m
myapp-deploy-7cbd5b69b9-p6kzm   /       Pending            1s
myapp-deploy-7cbd5b69b9-p6kzm   /       Pending            1s
myapp-deploy-7cbd5b69b9-p6kzm   /       ContainerCreating            1s
myapp-deploy-7cbd5b69b9-p6kzm   /       ContainerCreating            2s
myapp-deploy-869b888f66-dpwvk   /       Terminating            31m
myapp-deploy-869b888f66-dpwvk   /       Terminating            31m
myapp-deploy-869b888f66-dpwvk   /       Terminating            31m
myapp-deploy-7cbd5b69b9-p6kzm   /       Running            18s
myapp-deploy-869b888f66-frspv   /       Terminating            31m
myapp-deploy-7cbd5b69b9-q8mvs   /       Pending            0s
myapp-deploy-7cbd5b69b9-q8mvs   /       Pending            0s
myapp-deploy-7cbd5b69b9-q8mvs   /       ContainerCreating            0s
myapp-deploy-7cbd5b69b9-q8mvs   /       ContainerCreating            1s
myapp-deploy-869b888f66-frspv   /       Terminating            31m
myapp-deploy-869b888f66-frspv   /       Terminating            31m
myapp-deploy-869b888f66-frspv   /       Terminating            31m
myapp-deploy-869b888f66-frspv   /       Terminating            31m

回滚

查看现在有几个版本

 kubectl rollout history deploy  myapp-deploy
deployments "myapp-deploy"
REVISION    CHANGE-CAUSE
        <none>
        <none>
        <none>
        <none>

回滚到第0版(默认回滚上一版，可以通过 --to-revision指定版本)

$ kubectl rollout undo deploy  myapp-deploy --to-revision=
deployment "myapp-deploy" rolled back
#查看回滚情况
$ kubectl get pods -l  app=myapp -w
NAME                            READY     STATUS    RESTARTS   AGE
myapp-deploy-7cbd5b69b9-5s4sq   /       Running             6m
myapp-deploy-7cbd5b69b9-p6kzm   /       Running            1m
myapp-deploy-7cbd5b69b9-q8mvs   /       Running            54s
^[[Amyapp-deploy-869b888f66-7shh9   /       Pending            0s
myapp-deploy-869b888f66-7shh9   /       Pending            0s
myapp-deploy-869b888f66-7shh9   /       ContainerCreating            0s
myapp-deploy-869b888f66-7shh9   /       ContainerCreating            1s
myapp-deploy-869b888f66-7shh9   /       Running            3s
myapp-deploy-7cbd5b69b9-q8mvs   /       Terminating            5m
myapp-deploy-869b888f66-4l4cv   /       Pending            0s
myapp-deploy-869b888f66-4l4cv   /       Pending            0s
myapp-deploy-869b888f66-4l4cv   /       ContainerCreating            0s
myapp-deploy-869b888f66-4l4cv   /       ContainerCreating            1s
myapp-deploy-7cbd5b69b9-q8mvs   /       Terminating            5m
myapp-deploy-869b888f66-4l4cv   /       Running            2s
myapp-deploy-7cbd5b69b9-p6kzm   /       Terminating            6m
myapp-deploy-869b888f66-vwgj2   /       Pending            0s
myapp-deploy-869b888f66-vwgj2   /       Pending            0s
myapp-deploy-869b888f66-vwgj2   /       ContainerCreating            0s
myapp-deploy-7cbd5b69b9-q8mvs   /       Terminating            5m
myapp-deploy-7cbd5b69b9-q8mvs   /       Terminating            5m
myapp-deploy-7cbd5b69b9-p6kzm   /       Terminating            6m
myapp-deploy-869b888f66-vwgj2   /       ContainerCreating            1s
myapp-deploy-869b888f66-vwgj2   /       Running            3s
myapp-deploy-7cbd5b69b9-5s4sq   /       Terminating            11m
myapp-deploy-7cbd5b69b9-5s4sq   /       Terminating            11m
myapp-deploy-7cbd5b69b9-5s4sq   /       Terminating            11m
myapp-deploy-7cbd5b69b9-p6kzm   /       Terminating            6m
myapp-deploy-7cbd5b69b9-p6kzm   /       Terminating            6m
myapp-deploy-7cbd5b69b9-5s4sq   /       Terminating            11m
myapp-deploy-7cbd5b69b9-5s4sq   /       Terminating            11m

$ kubectl  get rs -l app=myapp -o wide
NAME                      DESIRED   CURRENT   READY     AGE       CONTAINER(S)       IMAGE(S)               SELECTOR
myapp-deploy-7cbd5b69b9                              14m       myapp-containers   ikubernetes/myapp:v3   app=myapp,pod-template-hash=,release=dev
myapp-deploy-869b888f66                              1h        myapp-containers   ikubernetes/myapp:v2   app=myapp,pod-template-hash=,release=dev
myapp-deploy-f4bcc4799                               1h        myapp-containers   ikubernetes/myapp:v1   app=myapp,pod-template-hash=,release=dev

kubectl patch 打补丁的方式更新

格式案例（通过json格式）

kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'

更新一个images

 kubectl patch  deploy myapp-deploy -p '{"spec":{"template":{"spec":{"containers":[{"name":"myapp-containers","image":"ikubernetes/myapp:v1"}]}}}}'