[root@centos ~]# kubectl get service
NAME         CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   10.254.0.1   <none>        443/TCP   12h
[root@centos ~]# kubectl describe services kubernetes
Name:			kubernetes
Namespace:		default
Labels:			component=apiserver
			provider=kubernetes
Selector:		<none>
Type:			ClusterIP
IP:			10.254.0.1
Port:			https	443/TCP
Endpoints:		192.168.10.115:6443
Session Affinity:	ClientIP
No events.

apiVersion: v1 
kind: ReplicationController  # 副本控制器 RC
metadata:
  name: mysql # RC名称，全局唯一
spec:
  replicas: 1 # Pod副本期待数量
  selector:
    app: mysql # 符合目标 Pod拥有此标签
  template:  # 根据此模板创建 Pod 的副本（实例）
    metadata:
      labels:
        app: mysql # Pod 副本拥有的标签，对应 RC 的Selector
    spec:
      containers:  # Pod 内容的定义部分
        - name: mysql #容器的名称
          image: mysql #容器对应的 Docker Image
        ports:
          - containerPort: 3306 # 容器暴露的端口号
        env:  # 注入到容器的环境变量
          - name: MYSQL_ROOT_PASSWORD 
            value: "123456"

[root@centos ~]# kubectl describe pod mysql
Name:		mysql-cvg6c
Namespace:	default
Node:		127.0.0.1/127.0.0.1
Start Time:	Sat, 03 Mar 2018 09:22:42 +0800
Labels:		app=mysql
Status:		Pending
IP:
Controllers:	ReplicationController/mysql
Containers:
  mysql:
    Container ID:
    Image:		mysql
    Image ID:
    Port:		3306/TCP
    State:		Waiting
      Reason:		ContainerCreating
    Ready:		False
    Restart Count:	0
    Volume Mounts:	<none>
    Environment Variables:
      MYSQL_ROOT_PASSWORD:	123456
Conditions:
  Type		Status
  Initialized 	True
  Ready 	False
  PodScheduled 	True
No volumes.
QoS Class:	BestEffort
Tolerations:	<none>
Events:
  FirstSeen	LastSeen	Count	From			SubObjectPath	Type		Reason		Message
  ---------	--------	-----	----			-------------	--------	------		-------
  8m		8m		1	{default-scheduler }			Normal		Scheduled	Successfully assigned mysql-cvg6c to 127.0.0.1
  8m		3m		6	{kubelet 127.0.0.1}			Warning		FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials on this request.  details: (open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory)"

  8m	12s	35	{kubelet 127.0.0.1}		Warning	FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image \"registry.access.redhat.com/rhel7/pod-infrastructure:latest\""

[root@centos ~]# kubectl describe pods mysql
Name:		mysql-j6vpx
Namespace:	default
Node:		127.0.0.1/127.0.0.1
Start Time:	Sat, 03 Mar 2018 09:51:30 +0800
Labels:		app=mysql
Status:		Pending
IP:
Controllers:	ReplicationController/mysql
Containers:
  mysql:
    Container ID:
    Image:		mysql
    Image ID:
    Port:		3306/TCP
    State:		Waiting
      Reason:		ContainerCreating
    Ready:		False
    Restart Count:	0
    Volume Mounts:	<none>
    Environment Variables:
      MYSQL_ROOT_PASSWORD:	123456
Conditions:
  Type		Status
  Initialized 	True
  Ready 	False
  PodScheduled 	True
No volumes.
QoS Class:	BestEffort
Tolerations:	<none>
Events:
  FirstSeen	LastSeen	Count	From			SubObjectPath		Type		Reason			Message
  ---------	--------	-----	----			-------------		--------	------			-------
  59m		59m		1	{default-scheduler }				Normal		Scheduled		Successfully assigned mysql-j6vpx to 127.0.0.1
  32m		32m		1	{kubelet 127.0.0.1}				Warning		MissingClusterDNS	kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
  32m		32m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Pulling			pulling image "mysql"
  1m		1m		1	{kubelet 127.0.0.1}				Warning		MissingClusterDNS	kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
  59s		59s		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Pulling			pulling image "mysql"

[root@centos ~]# kubectl describe pods mysql
Name:		mysql-j6vpx
Namespace:	default
Node:		127.0.0.1/127.0.0.1
Start Time:	Sat, 03 Mar 2018 09:51:30 +0800
Labels:		app=mysql
Status:		Running
IP:		172.17.0.2
Controllers:	ReplicationController/mysql
Containers:
  mysql:
    Container ID:	docker://0f1032ef9bd08438996e76c98f7f313b73a07ade76bf6b4b6b5c42de8dcba053
    Image:		mysql
    Image ID:		docker-pullable://docker.io/mysql@sha256:227d5c3f54ee3a70c075b1c3013e72781564000d34fc8c7ec5ec353c5b7ef7fa
    Port:		3306/TCP
    State:		Running
      Started:		Sat, 03 Mar 2018 10:51:26 +0800
    Ready:		True
    Restart Count:	0
    Volume Mounts:	<none>
    Environment Variables:
      MYSQL_ROOT_PASSWORD:	123456
Conditions:
  Type		Status
  Initialized 	True
  Ready 	True
  PodScheduled 	True
No volumes.
QoS Class:	BestEffort
Tolerations:	<none>
Events:
  FirstSeen	LastSeen	Count	From			SubObjectPath		Type		Reason			Message
  ---------	--------	-----	----			-------------		--------	------			-------
  33m		33m		1	{kubelet 127.0.0.1}				Warning		MissingClusterDNS	kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
  33m		33m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Pulling			pulling image "mysql"
  2m		2m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Pulling			pulling image "mysql"
  2m		1m		2	{kubelet 127.0.0.1}				Warning		MissingClusterDNS	kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
  1m		1m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Pulled			Successfully pulled image "mysql"
  1m		1m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Created			Created container with docker id 0f1032ef9bd0; Security:[seccomp=unconfined]
  1m		1m		1	{kubelet 127.0.0.1}	spec.containers{mysql}	Normal		Started			Started container with docker id 0f1032ef9bd0

[root@centos ~]# kubectl get services
NAME         CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
kubernetes   10.254.0.1      <none>        443/TCP          22h
mysql        10.254.248.63   <none>        3306/TCP         9h
myweb        10.254.193.35   <nodes>       8080:30001/TCP   32s