Kubernetes(4)deployment管理pod

Kubernetes(4)deployment管理pod

kubernetes cluster由master和node组成

master节点是kubernetes cluster的大脑，它同时也是一个node
1.API Server(k8s.gcr.io/kube-apiserver):是kubernetes cluster的前端接口，各种客户端工具以及kubernetes其他组件可以通过它管理cluster的各种资源
2.k8s.gcr.io/kube-scheduler:负责决定将pod放在哪个node上运行
3.k8s.gcr.io/kube-controller-manager:负责管理cluster各种资源，保证资源处于预期状态
4.k8s.gcr.io/etcd:负责保存集群的配置信息和各种资源的状态信息，当数据发生变化的时候，etcd会快速通知kubernetes相关组件
5.pod网络：pod要能够相互通信，kubernetes cluster必须部署pod网络，flannel是其中一个可选的方案

node节点
1.kubelet
2.kube-proxy
3.pod网络

几乎所有的kubernetes组建本身也运行在pod里面
[k8s@server1 ~]$ kubectl get pod --all-namespaces -o wide
我们将通过实践深入学习kubernetes的各种特性，
作为容器编排引擎，最重要也是最基本的功能当然是运行容器化应用

kubernetes通过各种controller来管理pod的生命周期，
为了满足不同的业务场景，kubernetes开发了多种,
我们首先学习最常用的deployment

deployment管理pod

1.1运行deployment
# 部署两个副本的 nginx-deployment 容器的image为nginx:1.7.9
[k8s@server1 ~]$ kubectl run nginx-deployment --image=nginx:1.7.9 --replicas=2
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/nginx-deployment created
# 通过kubectl get deployment命令查看nginx-deployment的状态，显示输出的两个副本正常运行
[k8s@server1 ~]$ kubectl get deployment nginx-deployment 
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   2/2     2            2           2m31s

# 获取更详细的信息
[k8s@server1 ~]$ kubectl describe deployment nginx-deployment
...
# 重点看这里
# 这里告诉我们创建了一个 replicaset(容器副本) nginx-deployment-748ff87d9d
# Events是 deployment的日志，记录了replicaset的启动过程

Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m24s  deployment-controller  Scaled up replica set nginx-deployment-748ff87d9d to 2

...
[k8s@server1 ~]$ kubectl get replicaset
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-748ff87d9d   2         2         2       16m

[k8s@server1 ~]$ kubectl describe replicaset nginx-deployment-748ff87d9d
Name:           nginx-deployment-748ff87d9d
Namespace:      default
Selector:       pod-template-hash=748ff87d9d,run=nginx-deployment
Labels:         pod-template-hash=748ff87d9d
                run=nginx-deployment
Annotations:    deployment.kubernetes.io/desired-replicas: 2
                deployment.kubernetes.io/max-replicas: 3
                deployment.kubernetes.io/revision: 1
# 指明replicaset是由Deployment/nginx-deployment创建的
Controlled By:  Deployment/nginx-deployment
Replicas:       2 current / 2 desired
Pods Status:    2 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  pod-template-hash=748ff87d9d
           run=nginx-deployment
  Containers:                     
   nginx-deployment:
    Image:        nginx:1.7.9
    Port:         <none>
    Host Port:    <none>
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Events:
  Type    Reason            Age   From                   Message
  ----    ------            ----  ----                   -------
  Normal  SuccessfulCreate  16m   replicaset-controller  Created pod: nginx-deployment-748ff87d9d-bxc8r
  Normal  SuccessfulCreate  16m   replicaset-controller  Created pod: nginx-deployment-748ff87d9d-25k5w

# 两个副本处于running状态
[k8s@server1 ~]$ kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-748ff87d9d-25k5w   1/1     Running   0          17m
nginx-deployment-748ff87d9d-bxc8r   1/1     Running   0          17m

# 获取更详细的信息
[k8s@server1 ~]$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
httpd-app-5bc589d9f7-pns4q          1/1     Running   0          31m
httpd-app-5bc589d9f7-qdq4z          1/1     Running   0          31m
nginx-deployment-748ff87d9d-25k5w   1/1     Running   0          17m
nginx-deployment-748ff87d9d-bxc8r   1/1     Running   0          17m

[k8s@server1 ~]$ kubectl describe pod nginx-deployment-748ff87d9d-25k5w
Name:           nginx-deployment-748ff87d9d-25k5w
Namespace:      default
Priority:       0
Node:           server3/172.25.0.3
Start Time:     Sat, 24 Aug 2019 14:52:14 +0800
Labels:         pod-template-hash=748ff87d9d
                run=nginx-deployment
Annotations:    <none>
Status:         Running
IP:             10.244.2.3
Controlled By:  ReplicaSet/nginx-deployment-748ff87d9d
Containers:
  nginx-deployment:
    Container ID:   docker://1c3dcd7cabea668eb5e947a1fbf9bf5b8837220c52b32e75eced9e198b4c3149
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 24 Aug 2019 14:54:44 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-zt8dv (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-zt8dv:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-zt8dv
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
# 记录了pod的启动过程，如果操作失败(eg:image不存在)，也可以在这里查到原因
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  20m   default-scheduler  Successfully assigned default/nginx-deployment-748ff87d9d-25k5w to server3
  Normal  Pulling    20m   kubelet, serv