K8S中Deployment控制器的概念、原理解读以及使用技巧

[root@master01 ~]# kubectl explain deployment
KIND:     Deployment
VERSION:  apps/v1
DESCRIPTION:
     Deployment enables declarative updates for Pods and ReplicaSets.
FIELDS:
   apiVersion <string>  #该资源使用的api版本
   kind <string>            #创建的资源是什么？
   metadata <Object>       #元数据，包括资源的名字和名称空间
   spec <Object>           #定义容器的
   status <Object>       #状态，不可以修改
#查看Deployment下的spec字段
[root@master01 ~]# kubectl explain deployment.spec
KIND:     Deployment
VERSION:  apps/v1
RESOURCE: spec <Object>
DESCRIPTION:
     Specification of the desired behavior of the Deployment.
     DeploymentSpec is the specification of the desired behavior of the
     Deployment.
FIELDS:
    minReadySeconds <integer>

[root@master01 ~]# kubectl explain deploy.spec.strategy
KIND:     Deployment
VERSION:  apps/v1
RESOURCE: strategy <Object>
DESCRIPTION:
     The deployment strategy to use to replace existing pods with new ones.
     DeploymentStrategy describes how to replace existing pods with new ones.
FIELDS:
   rollingUpdate  <Object>
   type <string>
     Type of deployment. Can be "Recreate" or "RollingUpdate". Default is
     RollingUpdate.
#支持两种更新，Recreate和RollingUpdate
#Recreate是重建式更新，删除一个更新一个

#RollingUpdate滚动更新，定义滚动更新方式，也就是pod能多几个，少几个
#查看Deployment下的spec.strategy.rollingUpdate字段
[root@master01 ~]# kubectl explain deploy.spec.strategy.rollingUpdate
KIND:     Deployment
VERSION:  apps/v1
RESOURCE: rollingUpdate <Object>
DESCRIPTION:
     Rolling update config params. Present only if DeploymentStrategyType =
     RollingUpdate.
     Spec to control the desired behavior of rolling update.
FIELDS:
   maxSurge <string>
#我们更新的过程当中最多允许超出的指定的目标副本数有几个； 
它有两种取值方式，第一种直接给定数量，第二种根据百分比，百分比表示原本是5个，
最多可以超出20%，那就允许多一个，最多可以超过40%，那就允许多两个
   maxUnavailable <string>
#最多允许几个不可用
假设有5个副本，最多一个不可用，就表示最少有4个可用

[root@master01 ~]# kubectl explain deploy.spec.template
KIND:     Deployment
VERSION:  apps/v1
RESOURCE: template <Object>
DESCRIPTION:
     Template describes the pods that will be created.
     PodTemplateSpec describes the data a pod should have when created from a template
FIELDS:
   metadata <Object>  #定义模板的名字
   spec <Object>   
deployment.spec.template为Pod定义的模板，和Pod定义不太一样，template中不包含apiVersion和Kind属性，
要求必须有metadata。deployment.spec.template.spec为容器的属性信息，其他定义内容和Pod一致。

[root@master01 ~]# kubectl explain deploy.spec.template.spec
KIND:     Deployment
VERSION:  apps/v1
RESOURCE: spec <Object>
DESCRIPTION:
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
     PodSpec is a description of a pod.
FIELDS:
   activeDeadlineSeconds  <integer>
#activeDeadlineSeconds表示Pod 可以运行的最长时间，达到设置的该值后，Pod 会自动停止。
   affinity <Object>  #定义亲和性，跟直接创建pod时候定义亲和性类似
   automountServiceAccountToken <boolean> #身份认证相关的
   containers <[]Object> -required- #定义容器属性
   dnsConfig  <Object>  #设置Pod的DNS
dnsConfig:
    nameservers:
      - 192.xxx.xxx.6
    searches:
      - xianchao.svc.cluster.local
      - my.dns.search.xianchao
   dnsPolicy  <string> # dnsPolicy决定Pod 内预设的DNS 配置策略

None 无任何策略：使用自定义的策略
Default 默认：使用宿主机的dns配置，/etc/resolv.conf
ClusterFirst 集群DNS优先，与 Default 相反，会预先使用 kube-dns (或 CoreDNS ) 的信息当预设置参数写入到该 Pod 内的DNS配置。
ClusterFirstWithHostNet 集群 DNS 优先，并伴随着使用宿主机网络：同时使用 hostNetwork 与 kube-dns 作为 Pod 预设 DNS 配置。

   enableServiceLinks <boolean>
   ephemeralContainers  <[]Object> #定义临时容器

hostAliases <[]Object> #在pod中增加域名解析的
  hostAliases:
  – ip: "10.1.2.2"
    hostnames:
    – "mc.local"
    – "rabbitmq.local"
  – ip: "10.1.2.3"
    hostnames:
    – "redis.local"
    – "mq.local"
   hostIPC  <boolean> #使用主机IPC
   hostNetwork  <boolean>  #是否使用宿主机的网络
   hostPID  <boolean> #可以设置容器里是否可以看到宿主机上的进程。True可以
   hostname <string>
   imagePullSecrets <[]Object>
   initContainers <[]Object> #定义初始化容器
   nodeName <string>  #定义pod调度到具体哪个节点上
   nodeSelector <map[string]string> #定义节点选择器
   overhead <map[string]string> #overhead是1.16引入的字段，在没有引入 Overhead 之前，
   只要一个节点的资源可用量大于等于 Pod 的 requests 时，这个 Pod 就可以被调度到这个节点上。
   引入 Overhead 之后，只有节点的资源可用量大于等于 Overhead 加上 requests 的和时才能被调度上来。
   preemptionPolicy <string>
   priority <integer>
   priorityClassName  <string>
   readinessGates <[]Object> 
   restartPolicy  <string>   #Pod重启策略
   runtimeClassName <string>
   schedulerName  <string>
   securityContext  <Object> #是否开启特权模式
     privileged: true  #开启特权模式
   serviceAccount <string>
   serviceAccountName <string>
   setHostnameAsFQDN  <boolean>
   shareProcessNamespace  <boolean>
   subdomain  <string>
   terminationGracePeriodSeconds  <integer>
#在真正删除容器之前，K8S会先发终止信号（kill -15 {pid}）给容器，默认30s
   tolerations  <[]Object>  #定义容忍度
   topologySpreadConstraints  <[]Object
   volumes  <[]Object>  #挂载存储卷

[root@master01 ~ ]# kubectl rollout --help
Manage the rollout of a resource.
  
 Valid resource types include:

  *  deployments
  *  daemonsets
  *  statefulsets

Examples:
  # Rollback to the previous deployment
  kubectl rollout undo deployment/abc
  
  # Check the rollout status of a daemonset
  kubectl rollout status daemonset/foo

Available Commands:
  history     View rollout history
  pause       Mark the provided resource as paused
  restart     Restart a resource
  resume      Resume a paused resource
  status      Show the status of the rollout
  undo        Undo a previous rollout

[root@master01 ~]# kubectl rollout undo deployment myapp-v1 --to-revision=1
deployment.apps/myapp-v1 rolled back
[root@master01 ~]# kubectl rollout history deployment myapp-v1
deployment.apps/myapp-v1 
REVISION  CHANGE-CAUSE
2         <none>
3         <none>

[root@master01 deploy ]#vim lv.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-v1
  namespace: blue-green
spec:
  replicas: 3
  selector:
   matchLabels:
    app: myapp
    version: v2
  template:
   metadata:
    labels:
     app: myapp
     version: v2
   spec:
    containers:
    - name: myapp
      image: janakiramm/myapp:v2
      imagePullPolicy: IfNotPresent
      ports:
      - containerPort: 80

[root@master01 deploy ]#kubectl create ns blue-green
namespace/blue-green created

[root@master01 deploy ]#vim service_lanlv.yaml 
apiVersion: v1
kind: Service
metadata:
  name: myapp-lan-lv
  namespace: blue-green
  labels:
    app: myapp
spec:
  type: NodePort
  ports:
  - port: 80
    nodePort: 30062
    name: http
  selector:
    app: myapp
    version: v2

[root@master01 deploy ]#kubectl apply -f service_lanlv.yaml 
service/myapp-lan-lv created

[root@master01 deploy ]#kubectl get svc -n blue-green
NAME           TYPE       CLUSTER-IP        EXTERNAL-IP   PORT(S)        AGE
myapp-lan-lv   NodePort   192.168.182.131   <none>        80:30062/TCP   18s

[root@master01 deploy ]#cat lan.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-v2
  namespace: blue-green
spec:
  replicas: 3
  selector:
   matchLabels:
    app: myapp
    version: v1
  template:
   metadata:
    labels:
     app: myapp
     version: v1
   spec:
    nodeName: node02
    containers:
    - name: myapp
      image: janakiramm/myapp:v1
      imagePullPolicy: IfNotPresent
      ports:
      - containerPort: 80

[root@master01 deploy ]#cat service_lanlv.yaml 
apiVersion: v1
kind: Service
metadata:
  name: myapp-lan-lv
  namespace: blue-green
  labels:
    app: myapp
spec:
  type: NodePort
  ports:
  - port: 80
    nodePort: 30062
    name: http
  selector:
    app: myapp
    version: v1

[root@master01 deployment]# kubectl delete -f lan.yaml 
[root@master01 deployment]# kubectl delete -f lv.yaml 
[root@master01 deployment]# kubectl delete -f service_lanlv.yaml

[root@master01 deploy ]#kubectl get pods -l app=myapp -n blue-green -w
NAME                      READY   STATUS              RESTARTS   AGE
myapp-v1-5898574c-jzdcw   0/1     ContainerCreating   0          10s
myapp-v1-5898574c-lq5mm   0/1     ContainerCreating   0          9s
myapp-v1-5898574c-qnr26   0/1     ContainerCreating   0          9s
myapp-v1-5898574c-jzdcw   0/1     ContainerCreating   0          26s
myapp-v1-5898574c-lq5mm   0/1     ContainerCreating   0          25s
myapp-v1-5898574c-qnr26   0/1     ContainerCreating   0          25s
myapp-v1-5898574c-jzdcw   1/1     Running             0          28s
myapp-v1-5898574c-lq5mm   1/1     Running             0          27s
myapp-v1-5898574c-qnr26   1/1     Running             0          28s

[root@master01 ~ ]#kubectl set image deployment myapp-v1 myapp=nginx  -n blue-green && kubectl rollout pause deployment myapp-v1 -n blue-green
deployment.apps/myapp-v1 image updated
deployment.apps/myapp-v1 paused

[root@master01 deploy ]#kubectl get pods -l app=myapp -n blue-green -w
NAME                      READY   STATUS    RESTARTS   AGE
myapp-v1-5898574c-69rls   1/1     Running   0          113s
myapp-v1-5898574c-bchnr   1/1     Running   0          113s
myapp-v1-5898574c-jvpgt   1/1     Running   0          113s
myapp-v1-7bcddfd466-thjpp   0/1     Pending   0          0s
myapp-v1-7bcddfd466-thjpp   0/1     ContainerCreating   0          0s
myapp-v1-7bcddfd466-thjpp   0/1     ContainerCreating   0          1s
myapp-v1-7bcddfd466-thjpp   1/1     Running             0          103s

[root@master01 ~ ]#curl 172.29.55.18
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Sample Deployment</title>
  <style>
    body {
      color: #ffffff;
      background-color: green;
      font-family: Arial, sans-serif;
      font-size: 14px;
    }

[root@master01 ~ ]#curl 172.29.55.19
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

[root@master01 deploy ]#kubectl get pods -l app=myapp -n blue-green -w
NAME                      READY   STATUS    RESTARTS   AGE
myapp-v1-5898574c-69rls   1/1     Running   0          113s
myapp-v1-5898574c-bchnr   1/1     Running   0          113s
myapp-v1-5898574c-jvpgt   1/1     Running   0          113s
myapp-v1-7bcddfd466-thjpp   0/1     Pending   0          0s
myapp-v1-7bcddfd466-thjpp   0/1     ContainerCreating   0          0s
myapp-v1-7bcddfd466-thjpp   0/1     ContainerCreating   0          1s
myapp-v1-7bcddfd466-thjpp   1/1     Running             0          103s
myapp-v1-7bcddfd466-c8wfd   0/1     Pending             0          0s
myapp-v1-5898574c-jvpgt     1/1     Terminating         0          12m
myapp-v1-7bcddfd466-c8wfd   0/1     ContainerCreating   0          0s
myapp-v1-5898574c-jvpgt     1/1     Terminating         0          12m
myapp-v1-7bcddfd466-c8wfd   0/1     ContainerCreating   0          1s
myapp-v1-5898574c-jvpgt     0/1     Terminating         0          12m
myapp-v1-5898574c-jvpgt     0/1     Terminating         0          12m
myapp-v1-5898574c-jvpgt     0/1     Terminating         0          12m
myapp-v1-7bcddfd466-c8wfd   1/1     Running             0          2s
myapp-v1-5898574c-69rls     1/1     Terminating         0          12m
myapp-v1-7bcddfd466-gncs2   0/1     Pending             0          0s
myapp-v1-7bcddfd466-gncs2   0/1     ContainerCreating   0          0s
myapp-v1-5898574c-69rls     1/1     Terminating         0          12m
myapp-v1-7bcddfd466-gncs2   0/1     ContainerCreating   0          1s
myapp-v1-7bcddfd466-gncs2   1/1     Running             0          1s
myapp-v1-5898574c-69rls     0/1     Terminating         0          12m
myapp-v1-5898574c-bchnr     1/1     Terminating         0          12m
myapp-v1-5898574c-69rls     0/1     Terminating         0          12m
myapp-v1-5898574c-69rls     0/1     Terminating         0          12m
myapp-v1-5898574c-bchnr     1/1     Terminating         0          12m
myapp-v1-5898574c-bchnr     0/1     Terminating         0          12m
myapp-v1-5898574c-bchnr     0/1     Terminating         0          12m
myapp-v1-5898574c-bchnr     0/1     Terminating         0          12m

[root@master01 ~ ]#kubectl get rs -n blue-green
NAME                  DESIRED   CURRENT   READY   AGE
myapp-v1-5898574c     0         0         0       13m
myapp-v1-7bcddfd466   3         3         3       11m

[root@master01 ~ ]#kubectl rollout history deploy myapp-v1 -n blue-green
deployment.apps/myapp-v1 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>