《每天5分钟玩转 Kubernetes》5.1.1 运行 Dep

kubectl run nginx-deployment --image=nginx:1.7.9 --replicas=2

deployment.apps/nginx-deployment created

部署了2个副本的 nginx-deployment，容器的 image 为 nginx:1.7.9。

查看 deployment：

kubectl get deployment nginx-deployment

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   2/2     2            2           6m22s

显示2个副本都正常运行，下面看一下详细信息：

kubectl describe deployment nginx-deployment

返回信息：

Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Wed, 12 Dec 2018 06:46:42 +0000
Labels:                 run=nginx-deployment
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               run=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:  run=nginx-deployment
  Containers:
   nginx-deployment:
    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-578fb949d8 (2/2 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  7m22s  deployment-controller  Scaled up replica set nginx-deployment-578fb949d8 to 2

内容比较易懂，其中 Conditions 下面有一条信息 NewReplicaSet: nginx-deployment-578fb949d8 (2/2 replicas created)，说明创建了 ReplicaSet，名称是 nginx-deployment-578fb949d8，下面就看一下 ReplicaSet：

kubectl describe replicaset nginx-deployment-578fb949d8

返回信息：

Name:           nginx-deployment-578fb949d8
Namespace:      default
Selector:       pod-template-hash=578fb949d8,run=nginx-deployment
Labels:         pod-template-hash=578fb949d8
                run=nginx-deployment
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:  pod-template-hash=578fb949d8
           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  17m   replicaset-controller  Created pod: nginx-deployment-578fb949d8-5wpfx
  Normal  SuccessfulCreate  17m   replicaset-controller  Created pod: nginx-deployment-578fb949d8-jxxbr

其中的 Controlled By 说明是由 Deployment/nginx-deployment 创建的，最下面的 Events 是日志，表明创建了2个 pod，看一下 pod 列表：

kubectl get pod

NAME                                   READY   STATUS    RESTARTS   AGE
nginx-deployment-578fb949d8-5wpfx      1/1     Running   0          22m
nginx-deployment-578fb949d8-jxxbr      1/1     Running   0          22m

下面再看 pod 的详细信息：

kubectl describe pod nginx-deployment-578fb949d8-5wpfx

返回信息：

Name:               nginx-deployment-578fb949d8-5wpfx
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               microk8s/10.0.2.15
Start Time:         Wed, 12 Dec 2018 06:46:42 +0000
Labels:             pod-template-hash=578fb949d8
                    run=nginx-deployment
Annotations:        <none>
Status:             Running
IP:                 10.1.1.106
Controlled By:      ReplicaSet/nginx-deployment-578fb949d8
Containers:
  nginx-deployment:
    Container ID:   docker://e9431c0e17ee5c2171c2b1d34d39f02f65073120fdcbae109fd75cb9fab6143c
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Wed, 12 Dec 2018 06:47:08 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-n44dv (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-n44dv:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-n44dv
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  24m   default-scheduler  Successfully assigned default/nginx-deployment-578fb949d8-5wpfx to microk8s
  Normal  Pulling    24m   kubelet, microk8s  pulling image "nginx:1.7.9"
  Normal  Pulled     23m   kubelet, microk8s  Successfully pulled image "nginx:1.7.9"
  Normal  Created    23m   kubelet, microk8s  Created container
  Normal  Started    23m   kubelet, microk8s  Started container

其中的 Controlled By 说明是 ReplicaSet/nginx-deployment-578fb949d8 创建的，Events 记录了 pod 的启动过程，如果出现问题，可以在这里查看原因。

总结一下启动过程：

1. 用户通过 kubectl 创建 deployment（nginx-deployment）
2. deployment（nginx-deployment）创建了 replicaset（nginx-deployment-578fb949d8）
3. replicaset（nginx-deployment-578fb949d8）创建了2个 pod (nginx-deployment-578fb949d8-5wpfx、nginx-deployment-578fb949d8-jxxbr)

从中可以看到对象的命名方式：父对象名字 + 随机字符串