一、Deployment

1. 运行Deployment

整体过程：

- 用户通过kubectl创建Deployment

- Deployment创建ReplicaSet

- ReplicaSet创建Pod

（1）运行一个deployment，命令将部署包含两个副本的Deployment nginx-deployment，容器镜像为nginx:1.7.9。

zy@k8s-master:~$ kubectl create deployment nginx-deployment --image=nginx:1.7.9 --replicas=2
deployment.apps/nginx-deployment created

（2）查看nginx-deployment状态，输出显示正常运行。

zy@k8s-master:~$ kubectl get deployments
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   2/2     2            2           3m44s

（3） 使用kubectl describe deployments 查看更详细的信息。

zy@k8s-master:~$ kubectl describe deployments
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Thu, 16 Mar 2023 00:38:26 +0800
Labels:                 app=nginx-deployment
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=nginx-deployment
Replicas:               2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx-deployment
  Containers:
   nginx:
    Image:        nginx:1.7.9
    Port:         <none>
    Host Port:    <none>
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-84b896cf65 (2/2 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  5m15s  deployment-controller  Scaled up replica set nginx-deployment-84b896cf65 to 2

（4） kubectl get replicaset 

验证了Deployment通过ReplicaSet来管理Pod的事实。

zy@k8s-master:~$ kubectl get replicaset
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-84b896cf65   2         2         2       8m41s

（5）kubectl describe replicaset

通过这句话Controlled By:  Deployment/nginx-deployment可以看出此ReplicaSet是由Deployment nginx-deployment创建的。

zy@k8s-master:~$ kubectl describe replicaset
Name:           nginx-deployment-84b896cf65
Namespace:      default
Selector:       app=nginx-deployment,pod-template-hash=84b896cf65
Labels:         app=nginx-deployment
                pod-template-hash=84b896cf65
Annotations:    deployment.kubernetes.io/desired-replicas: 2
                deployment.kubernetes.io/max-replicas: 3
                deployment.kubernetes.io/revision: 1
Controlled By:  Deployment/nginx-deployment
Replicas:       2 current / 2 desired
Pods Status:    2 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=nginx-deployment
           pod-template-hash=84b896cf65
  Containers:
   nginx:
    Image:        nginx:1.7.9
    Port:         <none>
    Host Port:    <none>
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Events:
  Type    Reason            Age   From                   Message
  ----    ------            ----  ----                   -------
  Normal  SuccessfulCreate  12m   replicaset-controller  Created pod: nginx-deployment-84b896cf65-2stcz
  Normal  SuccessfulCreate  12m   replicaset-controller  Created pod: nginx-deployment-84b896cf65-vqmgh

（6）kubectl get pod

zy@k8s-master:~$ kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-84b896cf65-2stcz   1/1     Running   0          19m
nginx-deployment-84b896cf65-vqmgh   1/1     Running   0          19m

（7）kubectl descirbe pod

通过这句话Controlled By:  ReplicaSet/nginx-deployment-84b896cf65指明Pod是由ReplicaSet nginx-deployment-84b896cf65创建的。Events记录了Pod的启动过程。

zy@k8s-master:~$ kubectl describe pod
Name:         nginx-deployment-84b896cf65-2stcz
Namespace:    default
Priority:     0
Node:         k8s-node2/192.168.65.141
Start Time:   Thu, 16 Mar 2023 00:38:26 +0800
Labels:       app=nginx-deployment
              pod-template-hash=84b896cf65
Annotations:  <none>
Status:       Running
IP:           10.244.2.3
IPs:
  IP:           10.244.2.3
Controlled By:  ReplicaSet/nginx-deployment-84b896cf65
Containers:
  nginx:
    Container ID:   docker://44e382b4dda9b104dbd74ba7463a2111990fe1cba5eb070a99b9bd3f9b02ad1e
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Thu, 16 Mar 2023 00:39:04 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-prt5v (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-prt5v:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-prt5v
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  21m   default-scheduler  Successfully assigned default/nginx-deployment-84b896cf65-2stcz to k8s-node2
  Normal  Pulling    21m   kubelet            Pulling image "nginx:1.7.9"
  Normal  Pulled     20m   kubelet            Successfully pulled image "nginx:1.7.9" in 37.234491722s
  Normal  Created    20m   kubelet            Created container nginx
  Normal  Started    20m   kubelet            Started container nginx


Name:         nginx-deployment-84b896cf65-vqmgh
Namespace:    default
Priority:     0
Node:         k8s-node1/192.168.65.142
Start Time:   Thu, 16 Mar 2023 00:38:26 +0800
Labels:       app=nginx-deployment
              pod-template-hash=84b896cf65
Annotations:  <none>
Status:       Running
IP:           10.244.1.5
IPs:
  IP:           10.244.1.5
Controlled By:  ReplicaSet/nginx-deployment-84b896cf65
Containers:
  nginx:
    Container ID:   docker://9805e1debeeee0a6a2fc0ab1956694e99f43001fedf84d712539e149d3faaeab
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Thu, 16 Mar 2023 00:39:03 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-prt5v (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-prt5v:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-prt5v
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type     Reason       Age   From               Message
  ----     ------       ----  ----               -------
  Normal   Scheduled    21m   default-scheduler  Successfully assigned default/nginx-deployment-84b896cf65-vqmgh to k8s-node1
  Warning  FailedMount  21m   kubelet            MountVolume.SetUp failed for volume "default-token-prt5v" : failed to sync secret cache: timed out waiting for the condition
  Normal   Pulling      21m   kubelet            Pulling image "nginx:1.7.9"
  Normal   Pulled       20m   kubelet            Successfully pulled image "nginx:1.7.9" in 34.475536479s
  Normal   Created      20m   kubelet            Created container nginx
  Normal   Started      20m   kubelet            Started container nginx

2. 命令 vs 配置文件

k8s支持两种创建资源的方式：

（1）用 kubectl 命令直接创建。

（2）通过配置文件和 kubectl apply 创建。

新建一个nginx.yml的文件如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

zy@k8s-master:~$ kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment created

kubectl apply不但能够创建k8s集群，也能对资源进行更新，非常方便。不过k8s还提供了几个类似的命令，例如kubectl create、kubectl replace、kubectl edit和 kubectl patch。尽量只使用kubectl apply。

删除deployment：

kubectl delete deployments.apps nginx-deployment

3. Deployment配置文件简介

以刚才的nginx.yml为例：

apiVersion: apps/v1：使用的 Kubernetes API 版本。
kind: Deployment：定义了一个 Deployment 对象。
metadata：定义 Deployment 的元数据信息，包括名称和标签。
spec：定义 Deployment 的规格信息，包括副本数、选择器、模板等。
replicas: 3：指定要创建的 Pod 副本数量为 3。
selector：定义了选择器，用于选择要管理的 Pod。
matchLabels：选择器的标签条件，这里使用 app: nginx，表示选择标签 app=nginx 的 Pod。
template：定义了要创建的 Pod 的模板。
metadata：模板的元数据信息，包括标签。
labels：定义 Pod 的标签。
containers：定义容器信息，包括容器名称、镜像、端口等。
name: nginx：定义容器名称为 nginx。
image: nginx:latest：定义容器使用的镜像为最新版本的 nginx。
ports：定义容器需要暴露的端口。
containerPort: 80：定义容器监听的端口为 80。

apiVersion: apps/v1         #当前配置格式的版本
kind: Deployment            #要创建的资源类型
metadata:                   #该资源的元数据 name是必须的元数据项
  name: nginx-deployment
  labels:
    app: nginx
spec:                      #spec是该Deployment的规格说明
  replicas: 3              #副本数量
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

4. 伸缩

伸缩指在线增加或减少Pod的副本数。

nginx-deployment初始是3个副本，修改nginx.yml文件，将副本改成5个：

replicas: 5

再次执行kubectl apply：

zy@k8s-master:~$ kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment configured

查看Pod：

zy@k8s-master:~$ kubectl get pod -o wide
NAME                               READY   STATUS    RESTARTS   AGE     IP            NODE        NOMINATED NODE   READINESS GATES
nginx-deployment-585449566-7bwvc   1/1     Running   0          5m24s   10.244.1.8    k8s-node1   <none>           <none>
nginx-deployment-585449566-bd2sv   1/1     Running   0          5m24s   10.244.2.6    k8s-node2   <none>           <none>
nginx-deployment-585449566-ghqgr   1/1     Running   0          2m17s   10.244.1.10   k8s-node1   <none>           <none>
nginx-deployment-585449566-lpsfr   1/1     Running   0          2m17s   10.244.1.9    k8s-node1   <none>           <none>
nginx-deployment-585449566-skk9r   1/1     Running   0          5m24s   10.244.2.5    k8s-node2   <none>           <none>

如果考虑将k8s-master也当作Node使用，可以执行：

kubectl taint node k8s-master node-role.kubernetes.io/master-

如果要恢复Master Only状态，执行如下命令：

kubectl taint node k8s-master node-role.kubernetes.io/master="":NoSchedule

将副本减少为两个，修改nginx.yml：

replicas: 2

只剩两个副本： 

zy@k8s-master:~$ kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment configured
zy@k8s-master:~$ kubectl get pod -o wide
NAME                               READY   STATUS    RESTARTS   AGE   IP           NODE        NOMINATED NODE   READINESS GATES
nginx-deployment-585449566-bd2sv   1/1     Running   0          18m   10.244.2.6   k8s-node2   <none>           <none>
nginx-deployment-585449566-skk9r   1/1     Running   0          18m   10.244.2.5   k8s-node2   <none>           <none>

5. Faliover

模拟k8s-node2故障，关闭该节点：

zy@k8s-node2:~$ sudo halt -h

等待一段时间k8s会检查到k8s-node2不可用，将k8s-node2上的pod标记为终止状态，并在k8s-node1上创建两个新的pod。

zy@k8s-master:~$ kubectl get pod -o wide
NAME                               READY   STATUS              RESTARTS   AGE   IP            NODE        NOMINATED NODE   READINESS GATES
nginx-deployment-585449566-bd2sv   1/1     Terminating         0          26m   10.244.2.6    k8s-node2   <none>           <none>
nginx-deployment-585449566-hx7kp   0/1     ContainerCreating   0          27s   <none>        k8s-node1   <none>           <none>
nginx-deployment-585449566-skk9r   1/1     Terminating         0          26m   10.244.2.5    k8s-node2   <none>           <none>
nginx-deployment-585449566-z54q5   1/1     Running             0          27s   10.244.1.11   k8s-node1   <none>      

6. 用label控制Pod的位置

默认配置下，Scheduler会将Pod调度到所有可用的Node。不过有些情况我们希望将pod部署到指定的Node。

（1）标记k8s-node1是配置了SSD的节点：

zy@k8s-master:~$ kubectl label node k8s-node1 disktype=ssd
node/k8s-node1 labeled

（2）查看节点的label：

disktype=ssd已经成功添加到k8s-node1上

zy@k8s-master:~$ kubectl get node --show-labels
NAME         STATUS   ROLES    AGE   VERSION    LABELS
k8s-master   Ready    master   17h   v1.19.10   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/master=
k8s-node1    Ready    <none>   17h   v1.19.10   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disktype=ssd,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node1,kubernetes.io/os=linux
k8s-node2    Ready    <none>   17h   v1.19.10   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node2,kubernetes.io/os=linux

（3）将指定的pod部署到k8s-node1

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 4
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80
      nodeSelector:   #指定类型
        disktype: ssd

重新apply一下：

zy@k8s-master:~$ kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment configured

查看pod，可以看到全都跑在k8s-node1上了

zy@k8s-master:~$ kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE     IP            NODE        NOMINATED NODE   READINESS GATES
nginx-deployment-5b5ff6dc64-2xvbg   1/1     Running   0          2m31s   10.244.1.16   k8s-node1   <none>           <none>
nginx-deployment-5b5ff6dc64-5zvdc   1/1     Running   0          3m5s    10.244.1.13   k8s-node1   <none>           <none>
nginx-deployment-5b5ff6dc64-qlg4j   1/1     Running   0          3m5s    10.244.1.14   k8s-node1   <none>           <none>
nginx-deployment-5b5ff6dc64-wdvcr   1/1     Running   0          2m47s   10.244.1.15   k8s-node1   <none>           <none>

（4）删除label disktype  -即删除

zy@k8s-master:~$ kubectl label node k8s-node1 disktype-
node/k8s-node1 labeled

二、DaemonSet

        Deployment部署的副本Pod会分布在各个Node上，每个Node都可能运行好几个副本。DaemonSet的不同之处在于：每个Node上最多只能运行一个副本。

        DaemonSet的典型应用场景：

        （1）在集群的每个节点上运行存储Daemon，比如glusterd或ceph。

        （2）在每个节点上运行日志收集Daemon，比如flunentd或logstash。

        （3）在每个节点上运行监控Daemon，比如Prometheus Node Exporter或collectd。

k8s自己就在用DaemonSet运行系统组件，执行如下命令：

zy@k8s-master:~$ kubectl get daemonsets.apps --namespace=kube-system
NAME         DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR            AGE
kube-proxy   3         3         3       3            3           kubernetes.io/os=linux   18h

DaemonSet kube-flannel-ds 和 kube-proxy 分别负责在每个节点上运行flannel和kube-proxy组件：

zy@k8s-master:~$ kubectl get pod --namespace=kube-system -o wide
NAME                                 READY   STATUS             RESTARTS   AGE   IP               NODE         NOMINATED NODE   READINESS GATES
coredns-6d56c8448f-fdgm2             0/1     Running            46         18h   10.244.0.2       k8s-master   <none>           <none>
coredns-6d56c8448f-mkgx2             0/1     CrashLoopBackOff   45         18h   10.244.0.3       k8s-master   <none>           <none>
etcd-k8s-master                      1/1     Running            0          18h   192.168.65.145   k8s-master   <none>           <none>
kube-apiserver-k8s-master            1/1     Running            2          18h   192.168.65.145   k8s-master   <none>           <none>
kube-controller-manager-k8s-master   1/1     Running            3          18h   192.168.65.145   k8s-master   <none>           <none>
kube-proxy-9rj9s                     1/1     Running            0          17h   192.168.65.142   k8s-node1    <none>           <none>
kube-proxy-sm5kd                     1/1     Running            0          18h   192.168.65.145   k8s-master   <none>           <none>
kube-proxy-vgzgz                     1/1     Running            1          17h   192.168.65.141   k8s-node2    <none>           <none>
kube-scheduler-k8s-master            1/1     Running            3          18h   192.168.65.145   k8s-master   <none>           <none>

三、Job

容器按照持续运行时间可以分为两类：服务类容器和工作类容器。

服务类容器需要一直运行，如http server、daemon等。工作类容器则是一次性任务，比如批处理程序，完成后容器就退出。

Kubernetes的Deployment、ReplicaSet和DaemonSet都用于管理服务类容器，对于工作类容器，用Job。

1. Pod成功情况

（1）写一个简单的Job配置文件 myjob.yml：

apiVersion: batch/v1
kind: Job
metadata:
    name: myjob
spec:
    template:
        metadata:
            name: myjob
        spec:
            containers:
            - name: hello
              image: busybox
              command: ["echo","hello zy and k8s job!"]
            restartPolicy: Never  #对于job 只能设置Never

（2）apply

zy@k8s-master:~$ kubectl apply -f myjob.yml 
job.batch/myjob created

（3）查看job状态

zy@k8s-master:~$ kubectl get pod
NAME                                READY   STATUS      RESTARTS   AGE
myjob-pqn57                         0/1     Completed   0          98s

（4）查看Pod的标准输出

zy@k8s-master:~$ kubectl logs myjob-pqn57 
hello zy and k8s job!