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05-kubernetes Pod控制器应用进阶

Pod 资源
实际操作
- livenessProbe 实战
  - livenessProbe exec 测试
  - livenessProbe httpGet 测试
- readinessProbe 就绪性探针
Pod 控制器

Pod 资源

spec.containers <[]object>
- name <string>
  image <string>
  imagePullPolicy <string>
    Always, Never, IfNotPresent

[root@master manifests]# kubectl get pods --show-labels
NAME                            READY   STATUS    RESTARTS   AGE    LABELS
myapp-84cd4b7f95-44qch          1/1     Running   0          7d5h   pod-template-hash=84cd4b7f95,run=myapp
myapp-84cd4b7f95-fzvsd          1/1     Running   0          7d5h   pod-template-hash=84cd4b7f95,run=myapp
myapp-84cd4b7f95-mlphg          1/1     Running   0          7d5h   pod-template-hash=84cd4b7f95,run=myapp
nginx-deploy-7689897d8d-lf8p7   1/1     Running   0          7d6h   pod-template-hash=7689897d8d,run=nginx-deploy
pod-demo                        2/2     Running   0          29s    app=myapp,tier=frontend

使用 -l 参数，来过滤标签

[root@master manifests]# kubectl get pods -l app
NAME       READY   STATUS    RESTARTS   AGE
pod-demo   2/2     Running   0          3m21s

给资源打标签

使用 kubectl label

Usage:
  kubectl label [--overwrite] (-f FILENAME | TYPE NAME) KEY_1=VAL_1 ... KEY_N=VAL_N [--resource-version=version] [options]

标签选择器

等之关系：=、==、!= 来进行操作
集合关系

KEY in (VALUE1,VALUE2,...)
KEY notin (VALUE1,VALUE2,...)

[root@master manifests]# kubectl get pods -l release
NAME                            READY   STATUS    RESTARTS   AGE
nginx-deploy-7689897d8d-lf8p7   1/1     Running   0          7d6h
pod-demo                        2/2     Running   0          11m
[root@master manifests]# kubectl get pods -l release=canary
NAME                            READY   STATUS    RESTARTS   AGE
nginx-deploy-7689897d8d-lf8p7   1/1     Running   0          7d6h
[root@master manifests]# kubectl get pods -l release,app
NAME       READY   STATUS    RESTARTS   AGE
pod-demo   2/2     Running   0          12m
[root@master manifests]# kubectl get pods -l release=stable,app=myapp
NAME       READY   STATUS    RESTARTS   AGE
pod-demo   2/2     Running   0          12m

许多资源支持内嵌字段定义其使用的标签选择器：

matchLabels: 直接给定键值
matchExpressions: 基于给定的表达式来定义使用标签选择器，{key:"KEY", operator: "OPERATOR", values: [VAL1,VAL2,...]}

操作符:

In, NotIn: values 字段的值必须为非空列表；
Exists, NotExists: values字段的值必须为空列表；

nodeSelector <map[string]string>

节点标签选择器，是可以影响pods调度算法的。

案例:

[root@master manifests]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP           NODE                NOMINATED NODE   READINESS GATES
nginx-deploy-7689897d8d-lf8p7   1/1     Running   0          8d    10.244.3.2   node02.kubernetes   <none>           <none>
[root@master manifests]# kubectl delete -f pod-demo.yaml 
pod "pod-demo" deleted
[root@master manifests]# vim pod-demo.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: pod-demo
  namespace: default
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
  - name: busybox
    image: busybox:latest
    imagePullPolicy: IfNotPresent
    command: 
    - "/bin/sh"
    - "-c"
    - "sleep 3600"
  nodeSelector:
    disktype: ssd
[root@master manifests]# kubectl create -f pod-demo.yaml 
pod/pod-demo created
[root@master manifests]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE                NOMINATED NODE   READINESS GATES
pod-demo                        2/2     Running   0          4s    10.244.3.10   node01.kubernetes   <none>           <none>

nodeName

指定调度到节点的名称

annoitations

与label不同的是，不能用于挑选资源对象，仅用于为对象提供"元数据"。

Pod 生命周期

POd生命周期

Pod声明周期主要分为两个阶段：

1. 初始化容器初始化阶段
2. 主容器正常运行阶段

Pod 状态：

1. 首先Pod进入初始化阶段，使用初始化容器完成初始化，可以有多个初始化容器，但是串行。
2. 初始化之后主容器进入正式运行阶段。
3. 主容器启动之后，会执行一次命令，就是 'post start'，也就是启动后钩子，执行结束后就退出了。
4. 命令执行只有，会有一个主容器存活状态检测，就是'liveness probe'。
5. 同时也会做就容器就绪性检测，检测主容器是否正常运行，就是 'readiness probe'。
6. 当主容器要退出的时候，也会有个结束前执行的命令，就是 'pre stop'，结束前钩子，这个Pod就退出。

探测行为：

liveness probe # 用于探测主容器是否存活
readiness probe # 判定容器中的主进程是否就绪，是否对外提供服务

无论哪一种，都支持三种。
1. 自定义命令
2. 向指定的TCP套接字发请求
3. 向指定的HTTP服务发请求

Pod 状态：

Pending : 调度尚未完成，没有适合创建的节点，不满足存活的状态。
Runing  : 运行状态
Failed  : 失败状态
Succeeded   : 成功状态
Unknown : 位置状态

创建Pod

1. 当用户创建Pod的时候，会去请求提交给apiserver，然后会把目标状态保存在ETCD中，
2. 然后 apiserver 会去请求 scheduler进行调度，并且把调度的结果保存在ETCD中之前保存的Pod状态中。
3. 一旦存在ETCD中发生更新，假如调度在node01上，node01 上的kubelet通过apiserver当中状态变化会知道。

restartPolicy:

Always, OnFailure, Never

实际操作

探针类型有三种：

1. ExecAction
2. TCPsocketAction
3. HTTPGetAction

这三种探针，livenessProbe 和 readinessProbe 都可以使用。

livenessProbe 实战

livenessProbe exec 测试

创建Pod的yaml文件：

[root@master manifests]# cat liveness-exec.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness-exec-pod
  namespace: default
spec:
  containers:
  - name: liveness-exec-container
    image: busybox:latest
    imagePullPolicy: IfNotPresent
    command: ["/bin/sh", "-c", "touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 3600"] # 生成存活性文件
    livenessProbe:
      exec:
        command: ["test", "-e", "/tmp/healthy"]     # 使用命令探测文件是否存在
      initialDelaySeconds: 1    # 容器启动后，多久开始探测，单位秒
      periodSeconds: 3          # 每次探测间隔时间，单位秒
      successThreshold: 1       # 成功几次
      failureThreshold: 2       # 失败几次后重启
      timeoutSeconds: 2         # 开始探测后的超时时间，单位秒
[root@master manifests]# kubectl create -f liveness-exec.yaml 
pod/liveness-exec-pod created
[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
liveness-exec-pod               1/1     Running   0          4s

等一会之后：

[root@master manifests]#kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
liveness-exec-pod               1/1     Running   1          2m20s
[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
liveness-exec-pod               1/1     Running   2          2m40s

查看详细信息：

[root@master manifests]# kubectl describe pod liveness-exec-pod
Name:         liveness-exec-pod
Namespace:    default
Priority:     0
Node:         node03.kubernetes/10.0.20.23
Start Time:   Fri, 19 Jul 2019 11:13:19 +0800
Labels:       <none>
Annotations:  <none>
Status:       Running
IP:           10.244.1.8
Containers:
  liveness-exec-container:
    Container ID:  docker://e028a5c4796c9e138e9669292f5b82fc76244017463039ef2141dab3da9d5cdd
    Image:         busybox:latest
    Image ID:      docker-pullable://busybox@sha256:c94cf1b87ccb80f2e6414ef913c748b105060debda482058d2b8d0fce39f11b9
    Port:          <none>
    Host Port:     <none>
    Command:
      /bin/sh
      -c
      touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 3600
    State:          Running
      Started:      Fri, 19 Jul 2019 11:14:34 +0800
    Last State:     Terminated
      Reason:       Error   # 这里提示错误
      Exit Code:    137
      Started:      Fri, 19 Jul 2019 11:13:20 +0800
      Finished:     Fri, 19 Jul 2019 11:14:34 +0800
    Ready:          True
    Restart Count:  1       # 提示被重启过一次
    Liveness:       exec [test -e /tmp/healthy] delay=1s timeout=2s period=10s #success=1 #failure=2
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-bc86p (ro)
      ........
      ........

livenessProbe httpGet 测试

创建Pod的yaml文件：

[root@master manifests]# cat liveness-httpget.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness-httpget-pod
  namespace: default
spec:
  containers:
  - name: liveness-httpget-container
    image: ikubernetes/myapp:v1     # 此镜像自带80端口
    imagePullPolicy: IfNotPresent
    ports:
    - name: http            # 这里定义映射端口名称
      containerPort: 80     # 指定端口
    livenessProbe:
      httpGet:
        port: http          # 这里直接使用定义的端口名称即可
        path: /index.html   # 定义探测http对应的路径
      initialDelaySeconds: 1
      periodSeconds: 3
      successThreshold: 1
      failureThreshold: 2
      timeoutSeconds: 2
[root@master manifests]# kubectl create -f liveness-httpget.yaml 
pod/liveness-httpget-pod created
[root@master manifests]# kubectl get pods
NAME                            READY   STATUS             RESTARTS   AGE
liveness-httpget-pod            1/1     Running            0          3s

手动进入到容器中，然后删除index.html 文件

[root@master ~]# kubectl exec -it liveness-httpget-pod -- /bin/sh
/ # rm -f /usr/share/nginx/html/index.html
/ # command terminated with exit code 137

再来查看刚刚创建的pod状态：

[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
liveness-httpget-pod            1/1     Running   1          7m14s      # 这里可以看到已经被重启过一次了
[root@master manifests]# kubectl describe pods liveness-httpget-pod     # 查看详细信息
Name:         liveness-httpget-pod
Namespace:    default
Priority:     0
Node:         node02.kubernetes/10.0.20.22
Start Time:   Fri, 19 Jul 2019 11:26:56 +0800
Labels:       <none>
Annotations:  <none>
Status:       Running
IP:           10.244.2.6
Containers:
  liveness-httpget-container:
    Container ID:   docker://39d3905acd7dac561905e77772522e652843dc3f2e0023a07586d3db088ca87f
    Image:          ikubernetes/myapp:v1
    Image ID:       docker-pullable://ikubernetes/myapp@sha256:9c3dc30b5219788b2b8a4b065f548b922a34479577befb54b03330999d30d513
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Fri, 19 Jul 2019 11:29:06 +0800
    Last State:     Terminated  # 状态不正常
      Reason:       Completed
      Exit Code:    0
      Started:      Fri, 19 Jul 2019 11:26:57 +0800
      Finished:     Fri, 19 Jul 2019 11:29:06 +0800
    Ready:          True
    Restart Count:  1           # 这里看到被重启过一次
    Liveness:       http-get http://:http/index.html delay=1s timeout=2s period=3s #success=1 #failure=2
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-bc86p (ro)
.... ....
.... ....

这里只会被重启过一次，因为当readinessProbe侦察到容器不处于就绪状态后，就会重启容器，重启的容器中index.html 文件又会被重新生产。

readinessProbe 就绪性探针

创建Pod的yaml文件，配置readinessProbe就绪性探针：

[root@master manifests]# cat readiness-httpget.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: readiness-httpget-pod
  namespace: default
spec:
  containers:
  - name: readiness-httpget-container
    image: ikubernetes/myapp:v1
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: http
        path: /index.html
      initialDelaySeconds: 1
      periodSeconds: 3
      successThreshold: 1
      failureThreshold: 2
      timeoutSeconds: 2
[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
readiness-httpget-pod           1/1     Running   0          53s

进入到 readiness-httpget-pod 中，手动删除index.html 主页文件，再次查看：

[root@master ~]# kubectl exec -it readiness-httpget-pod -- /bin/sh
/ # rm -rf /usr/share/nginx/html/index.html 
/ # ps  aux
PID   USER     TIME   COMMAND
    1 root       0:00 nginx: master process nginx -g daemon off;    # nginx依然运行这
    6 nginx      0:00 nginx: worker process
    7 root       0:00 /bin/sh
   13 root       0:00 ps aux

[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
readiness-httpget-pod           0/1     Running   0          60s    # 就绪状态的pod为 0 个
[root@master manifests]# kubectl describe pods readiness-httpget-pod
Name:         readiness-httpget-pod
Namespace:    default
Priority:     0
Node:         node03.kubernetes/10.0.20.23
Start Time:   Mon, 22 Jul 2019 09:09:50 +0800
Labels:       <none>
Annotations:  <none>
Status:       Running
IP:           10.244.1.9
Containers:
  readiness-httpget-container:
    Container ID:   docker://71009463c970b6712d97c8692990caa8c2192841b6e075a1d0db9ac15a2d1cd7
    Image:          ikubernetes/myapp:v1
    Image ID:       docker-pullable://ikubernetes/myapp@sha256:9c3dc30b5219788b2b8a4b065f548b922a34479577befb54b03330999d30d513
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Mon, 22 Jul 2019 09:09:51 +0800
    Ready:          False
    Restart Count:  0
    Readiness:      http-get http://:http/index.html delay=1s timeout=2s period=3s #success=1 #failure=2
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-bc86p (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False   # 详细信息中，显示为错误。
  ContainersReady   False 
  PodScheduled      True
  .... ....
  .... ....

当就绪性探针发现此Pod不可用时，service 调度会把此pod剔除集群

手动此创建Pod中的index.html文件：

/ # echo 'hi' > /usr/share/nginx/html/index.html

[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
readiness-httpget-pod           1/1     Running   0          118s

已经恢复，此时service 又会把此Pod 重新加入到集群中。

Pod 控制器

ReplicaSet:
1. 用户期望的Pod副本数量，支持多删少补
2. 标签选择器，一遍选择自己管理和控制Pod副本
3. Pod资源模板来完成Pod资源的新建
Deployment:
1. 工作在ReplicaSet之上，不直接控制Pod，而是控制ReplicaSet
2. 支持滚动更新和回滚等，可滚动更新或回滚
3. 提供声明式配置功能
DaemonSet
1. 无状态的，必须是守护进程类的，
2. 确保kubernetes所有节点只运行一个Pod
3. 保障系统级的后台任务
4. 只能管控无状态应用，关注群体，不关注个体
Job
1. 只能执行一次性的作业
Cronjob
1. 周期性执行，不执行不启动
StatefulSet
1. 管理有状态应用
TPR

Third Party Resources, 1.2 版本开始能用，1.7版本后不可用
第三方资源
CDR

Custom Defined Resource, 1.8 版本之后可用
第三方资源

ReplicaSet 控制器

创建一个ReplicaSet清单文件

[root@master manifests]# cat rs-demo.yaml 
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: myapp
  namespace: default
spec:
  replicas: 2       # Pod 副本数为 2
  selector:
    matchLabels:    # 定义标签选择器
      app: myapp
      release: canary
  template:         # 这里以下定义的和一个单独的Pod清单文件一样
    metadata:       # 定义Pod对应的标签，会被ReplicaSet控制器选择
      name: myapp-pod
      namespace: default
      labels:
        app: myapp
        release: canary
        environment: qa
    spec:
      containers:
      - name: myapp-container
        image: ikubernetes/myapp:v1
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 80
[root@master manifests]# kubectl create -f rs-demo.yaml 
replicaset.apps/myapp created
[root@master manifests]# kubectl get pods -o wide
NAME          READY   STATUS    RESTARTS   AGE   IP            NODE                NOMINATED NODE   READINESS GATES
myapp-k4m9l   1/1     Running   0          27s   10.244.1.13   node03.kubernetes   <none>           <none>
myapp-p9dk9   1/1     Running   0          27s   10.244.3.14   node01.kubernetes   <none>           <none>

两个副本的Pod已经被创建。

可以直接使用kubectl edit 来编辑：

[root@master manifests]# kubectl edit rs myapp
replicaset.extensions/myapp edited      # 这里打开后，把replicas的值变更为3，也就是增加一个后。
[root@master manifests]# kubectl get pods -o wide
NAME          READY   STATUS    RESTARTS   AGE   IP            NODE                NOMINATED NODE   READINESS GATES
myapp-p9dk9   1/1     Running   0          14m   10.244.3.14   node01.kubernetes   <none>           <none>
myapp-vjnlq   1/1     Running   0          8s    10.244.1.14   node03.kubernetes   <none>           <none>
myapp-wl9nh   1/1     Running   0          10m   10.244.2.10   node02.kubernetes   <none>           <none>      # 这里立刻就会再次创建一个Pod 出来

道理相同，减少replicas的数量的时候，Pod对应的数量也会减少，、
也可以直接编辑对应的Pod版本，只是编辑后不会自动更新，但当手动删除一个Pod的时候，再次自动创建新的Pod的时候，就会更新清单中的Pod。

[root@master manifests]# kubectl edit rs myapp
replicaset.extensions/myapp edited
[root@master manifests]# kubectl get rs -o wide
NAME    DESIRED   CURRENT   READY   AGE   CONTAINERS        IMAGES                 SELECTOR
myapp   3         3         3       15m   myapp-container   ikubernetes/myapp:v2   app=myapp,release=canary
[root@master manifests]# curl 10.244.3.14
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
[root@master manifests]# kubectl delete pods myapp-p9dk9
pod "myapp-p9dk9" deleted
[root@master manifests]# kubectl get pods -o wide
NAME          READY   STATUS    RESTARTS   AGE     IP            NODE                NOMINATED NODE   READINESS GATES
myapp-fwnwz   1/1     Running   0          14s     10.244.3.15   node01.kubernetes   <none>           <none>
myapp-vjnlq   1/1     Running   0          2m33s   10.244.1.14   node03.kubernetes   <none>           <none>
myapp-wl9nh   1/1     Running   0          12m     10.244.2.10   node02.kubernetes   <none>           <none>
[root@master manifests]# curl 10.244.3.15
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

基于这种策略，可以实现蓝绿发布，具体实现如下图：

ReplicaSet实现蓝绿发布图

Deployment 控制器

这里直接使用声明式创建，使用kubectl apply命令

首先创建清单

root@master manifests]# cat deploy-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2   # 副本数为 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
        ports:
        - name: http
          containerPort: 80
[root@master manifests]# kubectl apply -f deploy-demo.yaml 
deployment.apps/myapp-deploy created

查看：

root@master manifests]# kubectl get pods
NAME                           READY   STATUS    RESTARTS   AGE
myapp-deploy-f4db5d79c-md2kk   1/1     Running   0          4s
myapp-deploy-f4db5d79c-wwx5n   1/1     Running   0          4s
[root@master manifests]# kubectl get deploy
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
myapp-deploy   2/2     2            2           11s
[root@master manifests]# kubectl get rs
NAME                     DESIRED   CURRENT   READY   AGE
myapp-deploy-f4db5d79c   2         2         2       43s

2个Pod创建成功并正常运行
Deployment 正常
Deployment 会自动创建一个ReplicaSet，通过管理ReplicaSet，ReplicaSet再去管理Pod。
Pod的名称是Deployment名称加上ReplicaSet最后面生产的hash值，再跟上自己的Hash值组成

查看 deployment 详细信息

root@master manifests]# kubectl get deploy
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
myapp-deploy   3/3     3            3           2m34s
[root@master manifests]# kubectl describe deploy myapp-deploy
Name:                   myapp-deploy
Namespace:              default
CreationTimestamp:      Tue, 23 Jul 2019 17:05:49 +0800
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1        # 每次的变化，都会被保存在 Annotations当中
                        kubectl.kubernetes.io/last-applied-configuration:
                          {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"name":"myapp-deploy","namespace":"default"},"spec":{"replicas":3...
Selector:               app=myapp,release=canary
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate       # 默认的更新策略，滚动更新
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge  # 最大不可用是25%，最大可用是25%，不足一个的时候，补足一个
Pod Template:
  Labels:  app=myapp
           release=canary
  Containers:
   myapp:
    Image:        ikubernetes/myapp:v1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Progressing    True    NewReplicaSetAvailable
  Available      True    MinimumReplicasAvailable
OldReplicaSets:  <none>
NewReplicaSet:   myapp-deploy-f4db5d79c (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m15s  deployment-controller  Scaled up replica set myapp-deploy-f4db5d79c to 2
  Normal  ScalingReplicaSet  50s    deployment-controller  Scaled up replica set myapp-deploy-f4db5d79c to 3

测试滚动更新

在一个窗口上来监控标签 app=myapp 的Pod

[root@master manifests]# kubectl get pods -l app=myapp -w       # 这里执行后，会一直等待不动，知道有变化才会有更新
NAME                           READY   STATUS    RESTARTS   AGE
myapp-deploy-f4db5d79c-cvvl6   1/1     Running   0          2m20s
myapp-deploy-f4db5d79c-md2kk   1/1     Running   0          4m45s
myapp-deploy-f4db5d79c-wwx5n   1/1     Running   0          4m45s

在另一个窗口，重新编辑清单deploy-demo.yaml文件中的副本数为 5

[root@master manifests]# cat deploy-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 5       # 这里副本数修改为 5
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 80

然后直接使用kubectl apply命令声明式方式来变更

[root@master manifests]# kubectl apply -f deploy-demo.yaml 
deployment.apps/myapp-deploy configured

当执行完成后，监控的窗口就会出现变化

[root@master manifests]# kubectl get pods -l app=myapp -w
NAME                           READY   STATUS    RESTARTS   AGE
myapp-deploy-f4db5d79c-cvvl6   1/1     Running   0          2m20s
myapp-deploy-f4db5d79c-md2kk   1/1     Running   0          4m45s
myapp-deploy-f4db5d79c-wwx5n   1/1     Running   0          4m45s
myapp-deploy-f4db5d79c-cvvl6   1/1     Terminating   0          3m26s
myapp-deploy-55b78d8548-zsl5d   0/1     Pending       0          0s
myapp-deploy-55b78d8548-zsl5d   0/1     Pending       0          0s
myapp-deploy-55b78d8548-zsl5d   0/1     ContainerCreating   0          0s
myapp-deploy-f4db5d79c-cvvl6    0/1     Terminating         0          3m27s
myapp-deploy-55b78d8548-zsl5d   1/1     Running             0          1s
myapp-deploy-f4db5d79c-md2kk    1/1     Terminating         0          5m52s
myapp-deploy-55b78d8548-l264b   0/1     Pending             0          0s
myapp-deploy-55b78d8548-l264b   0/1     Pending             0          0s
myapp-deploy-55b78d8548-l264b   0/1     ContainerCreating   0          0s
myapp-deploy-f4db5d79c-cvvl6    0/1     Terminating         0          3m28s
myapp-deploy-f4db5d79c-cvvl6    0/1     Terminating         0          3m28s
myapp-deploy-f4db5d79c-md2kk    0/1     Terminating         0          5m53s
myapp-deploy-55b78d8548-l264b   1/1     Running             0          2s
myapp-deploy-f4db5d79c-wwx5n    1/1     Terminating         0          5m54s
myapp-deploy-f4db5d79c-wwx5n    0/1     Terminating         0          5m54s
myapp-deploy-f4db5d79c-md2kk    0/1     Terminating         0          6m1s
myapp-deploy-f4db5d79c-md2kk    0/1     Terminating         0          6m1s
myapp-deploy-f4db5d79c-wwx5n    0/1     Terminating         0          6m4s
myapp-deploy-f4db5d79c-wwx5n    0/1     Terminating         0          6m4s

此时来再查看

[root@master manifests]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
myapp-deploy-55b78d8548-cw4r5   1/1     Running   0          5s
myapp-deploy-55b78d8548-jwj2j   1/1     Running   0          5s
myapp-deploy-55b78d8548-l264b   1/1     Running   0          4m20s
myapp-deploy-55b78d8548-mnm95   1/1     Running   0          5s
myapp-deploy-55b78d8548-zsl5d   1/1     Running   0          4m21s

查看 ReplicaSet

[root@master manifests]# kubectl get rs -o wide
NAME                      DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                 SELECTOR
myapp-deploy-55b78d8548   5         5         5       59s     myapp        ikubernetes/myapp:v2   app=myapp,pod-template-hash=55b78d8548,release=canary
myapp-deploy-f4db5d79c    0         0         0       6m50s   myapp        ikubernetes/myapp:v1   app=myapp,pod-template-hash=f4db5d79c,release=canary

查看ReplicaSet后发现有两个，因为Deployment 会重新创建一个ReplicaSet来更新，IMAGES版本一列可以看出版本的不同，通过把新的Pod创建在新的ReplicaSet上来实现滚动更新

DaemonSet 控制器

DaemonSet 控制器主要用于系统级别的无状态环境。
默认创会在 kubernetes 集群中每一个节点创建一个Pod。

创建一个DaemonSet配置清单

[root@master manifests]# cat daemonset-demo.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: myapp-ds
  namespace: default
spec:
  selector:
    matchLabels:
      app: filebeat
      release: stable
  template:
    metadata:
      labels:
        app: filebeat
        release: stable
    spec:
      containers:
      - name: filebeat
        image: ikubernetes/filebeat:5.6.5-alpine    # 这里使用filebeat来进行测试
        env:                                        # 增加两个环境变量
        - name: REDIS_HOST                          # 指定redis地址
          value: redis.default.svc.cluster.local    # 这里使用集群域名来解析redis地址
        - name: REDIS_LOG_LEVEL                     # 指定日志级别
          value: info                               # 日志级别为info
[root@master manifests]# kubectl apply -f daemonset-demo.yaml 
daemonset.apps/myapp-ds created
[root@master manifests]# kubectl get pods -o wide
NAME                           READY   STATUS    RESTARTS   AGE   IP            NODE                NOMINATED NODE   READINESS GATES
myapp-ds-jxwfq                 1/1     Running   0          9s    10.244.1.22   node03.kubernetes   <none>           <none>
myapp-ds-mw9vw                 1/1     Running   0          9s    10.244.3.25   node01.kubernetes   <none>           <none>
myapp-ds-xjqdb                 1/1     Running   0          9s    10.244.2.18   node02.kubernetes   <none>           <none>

可以看到已经被创建成功，并且是每个节点都只有一个Pod。

查看详细信息

[root@master manifests]# kubectl describe ds myapp-ds
Name:           myapp-ds
Selector:       app=filebeat,release=stable
Node-Selector:  <none>
Labels:         <none>
Annotations:    deprecated.daemonset.template.generation: 1
                kubectl.kubernetes.io/last-applied-configuration:
                  {"apiVersion":"apps/v1","kind":"DaemonSet","metadata":{"annotations":{},"name":"myapp-ds","namespace":"default"},"spec":{"selector":{"matc...
Desired Number of Nodes Scheduled: 3
Current Number of Nodes Scheduled: 3
Number of Nodes Scheduled with Up-to-date Pods: 3
Number of Nodes Scheduled with Available Pods: 3
Number of Nodes Misscheduled: 0
Pods Status:  3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=filebeat
           release=stable
  Containers:
   filebeat:
    Image:      ikubernetes/filebeat:5.6.5-alpine
    Port:       <none>
    Host Port:  <none>
    Environment:
      REDIS_HOST:       redis.default.svc.cluster.local
      REDIS_LOG_LEVEL:  info
    Mounts:             <none>
  Volumes:              <none>
Events:
  Type    Reason            Age   From                  Message
  ----    ------            ----  ----                  -------
  Normal  SuccessfulCreate  22m   daemonset-controller  Created pod: myapp-ds-qjg6w
  Normal  SuccessfulCreate  22m   daemonset-controller  Created pod: myapp-ds-ftxzb
  Normal  SuccessfulCreate  22m   daemonset-controller  Created pod: myapp-ds-66hnj

同样，一个配置清单中，可以把多个资源配置写在一个清单中，使用 --- 来分割

在相同的清单文件中，再定义一个redis 的 Deployment

[root@master manifests]# cat daemonset-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
      role: logstor
  template:
    metadata:
      labels:
        app: redis
        role: logstor
    spec:
      containers:
      - name: redis
        image: redis:4.0-alpine
        ports:
        - name: redis
          containerPort: 6379
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: myapp-ds
  namespace: default
spec:
  selector:
    matchLabels:
      app: filebeat
      release: stable
  template:
    metadata:
      labels:
        app: filebeat
        release: stable
    spec:
      containers:
      - name: filebeat
        image: ikubernetes/filebeat:5.6.5-alpine
        env:
        - name: REDIS_HOST
          value: redis.default.svc.cluster.local
        - name: REDIS_LOG_LEVEL
          value: info

再次使用 kubectl apply 来执行此清单文件

[root@master manifests]# kubectl apply -f daemonset-demo.yaml 
deployment.apps/redis created
daemonset.apps/myapp-ds created
[root@master manifests]# kubectl get pods
NAME                           READY   STATUS    RESTARTS   AGE
myapp-ds-66hnj                 1/1     Running   0          59s
myapp-ds-ftxzb                 1/1     Running   0          59s
myapp-ds-qjg6w                 1/1     Running   0          59s
redis-5c998b644f-wnzrd         1/1     Running   0          59s

创建一个redis 的service

[root@master manifests]# kubectl expose deployment redis --port=6379
service/redis exposed
[root@master manifests]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP    15d
redis        ClusterIP   10.111.151.200   <none>        6379/TCP   4s

进入到redis pod中，并尝试解析redis

[root@master manifests]# kubectl exec -it redis-5c998b644f-wnzrd -- /bin/sh
/data # netstat -tnl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       
tcp        0      0 0.0.0.0:6379            0.0.0.0:*               LISTEN      
tcp        0      0 :::6379                 :::*                    LISTEN      
/data # ls
/data # nslookup redis.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve

Name:      redis.default.svc.cluster.local
Address 1: 10.111.151.200 redis.default.svc.cluster.local       # 可以看到解析正常

同样，DaemonSet 也支持滚动更新，但个Deployment不同的时候，DaemonSet只支持删除Pod后再次新建，来进行更新

更新方式有好几种，这里使用 kubectl set image 来更新

[root@master manifests]# kubectl set image daemonset myapp-ds filebeat=ikubernetes/filebeat:5.6.6-alpine
daemonset.extensions/myapp-ds image updated
[root@master manifests]# kubectl get pods -o wide -w
NAME                           READY   STATUS              RESTARTS   AGE   IP            NODE                NOMINATED NODE   READINESS GATES
myapp-deploy-f4db5d79c-7hnfg   1/1     Running             0          22h   10.244.2.16   node02.kubernetes   <none>           <none>
myapp-deploy-f4db5d79c-85hpm   1/1     Running             0          22h   10.244.3.22   node01.kubernetes   <none>           <none>
myapp-deploy-f4db5d79c-b9h4s   1/1     Running             0          22h   10.244.2.15   node02.kubernetes   <none>           <none>
myapp-deploy-f4db5d79c-tm9mt   1/1     Running             0          22h   10.244.1.20   node03.kubernetes   <none>           <none>
myapp-deploy-f4db5d79c-xp8t6   1/1     Running             0          22h   10.244.3.23   node01.kubernetes   <none>           <none>
myapp-ds-8tvmc                 0/1     ContainerCreating   0          10s   <none>        node03.kubernetes   <none>           <none>
myapp-ds-f2pp8                 1/1     Running             0          30s   10.244.2.20   node02.kubernetes   <none>           <none>
myapp-ds-ftxzb                 1/1     Running             0          25m   10.244.3.26   node01.kubernetes   <none>           <none>
redis-5c998b644f-wnzrd         1/1     Running             0          25m   10.244.1.24   node03.kubernetes   <none>           <none>
myapp-ds-8tvmc                 1/1     Running             0          14s   10.244.1.25   node03.kubernetes   <none>           <none>
myapp-ds-ftxzb                 1/1     Terminating         0          25m   10.244.3.26   node01.kubernetes   <none>           <none>
myapp-ds-ftxzb                 0/1     Terminating         0          25m   10.244.3.26   node01.kubernetes   <none>           <none>
myapp-ds-ftxzb                 0/1     Terminating         0          25m   10.244.3.26   node01.kubernetes   <none>           <none>
myapp-ds-ftxzb                 0/1     Terminating         0          25m   10.244.3.26   node01.kubernetes   <none>           <none>
myapp-ds-cs2hw                 0/1     Pending             0          0s    <none>        <none>              <none>           <none>
myapp-ds-cs2hw                 0/1     Pending             0          0s    <none>        node01.kubernetes   <none>           <none>
myapp-ds-cs2hw                 0/1     ContainerCreating   0          0s    <none>        node01.kubernetes   <none>           <none>
myapp-ds-cs2hw                 1/1     Running             0          17s   10.244.3.27   node01.kubernetes   <none>           <none>

这里会一个一个更新，删除后下载镜像更新启动Pod。

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原文地址：https://www.cnblogs.com/winstom/p/11243090.html