Docker实践—CentOS7上部署Kubernetes详解

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Kubernetes架构

Kubernetes的整体架构如下：

Master为主控节点，上面运行apiserver，scheduler，controller-manager等组件。Minion相当于工作节点，上面运行kubelet，proxy，cAdvisor以及最重要的docker等组件。下面来实际部署一下这套集群管理工具。

环境

yy1 10.193.6.35

yy2 10.193.6.36

yy1作为master，yy2作为minion。

# cat /etc/centos-release

CentOS Linux release 7.0.1406 (Core)

安装kubernetes

# curl https://copr.fedoraproject.org/coprs/eparis/kubernetes-epel-7/repo/epel-7/eparis-kubernetes-epel-7-epel-7.repo -o /etc/yum.repos.d/eparis-kubernetes-epel-7-epel-7.repo

# yum install kubernetes -y

配置yy1

# cat /etc/kubernetes/apiserver

###

# kubernetes system config

#

# The following values are used to configure the kubernetes-apiserver

#

 

# The address on the local server to listen to.

KUBE_API_ADDRESS="10.193.6.35"

 

# The port on the local server to listen on.

KUBE_API_PORT="8080"

 

# How the replication controller and scheduler find the apiserver

KUBE_MASTER="10.193.6.35:8080"

 

# Comma seperated list of minions

MINION_ADDRESSES="10.193.6.36"

 

# Port minions listen on

MINION_PORT="10250"

 

# cat /etc/kubernetes/config

###

# kubernetes system config

#

# The following values are used to configure various aspects of all

# kubernetes services, including

#

#  kubernetes-apiserver.service

#  kubernetes-controller-manager.service

#  kubernetes-kubelet.service

#  kubernetes-proxy.service

 

# Comma seperated list of nodes in the etcd cluster

KUBE_ETCD_SERVERS="http://10.193.6.35:4001"

 

# logging to stderr means we get it in the systemd journal

KUBE_LOGTOSTDERR="true"

 

# journal message level, 0 is debug

KUBE_LOG_LEVEL=0

 

# Should this cluster be allowed to run privleged docker containers

KUBE_ALLOW_PRIV="true"

启动yy1上相关服务

master上需要运行etcd，kube-apiserver，kube-controller-manager，kube-scheduler这4个进程。

for SERVICES in etcd kube-apiserver kube-controller-manager kube-scheduler; do

  systemctl restart $SERVICES

  systemctl enable $SERVICES

  systemctl status $SERVICES

done

配置yy2

# cat /etc/kubernetes/kubelet

###

# kubernetes kublet (minion) config

 

# The address for the info server to serve on

MINION_ADDRESS="10.193.6.36"

 

# The port for the info server to serve on

MINION_PORT="10250"

# You may leave this blank to use the actual hostname

MINION_HOSTNAME="10.193.6.36"

# cat /etc/kubernetes/config 

###

# kubernetes system config

#

# The following values are used to configure various aspects of all

# kubernetes services, including

#

#  kubernetes-apiserver.service

#  kubernetes-controller-manager.service

#  kubernetes-kubelet.service

#  kubernetes-proxy.service

# Comma seperated list of nodes in the etcd cluster

KUBE_ETCD_SERVERS="http://10.193.6.35:4001"

 

# logging to stderr means we get it in the systemd journal

KUBE_LOGTOSTDERR="true"

# journal message level, 0 is debug

KUBE_LOG_LEVEL=0

# Should this cluster be allowed to run privleged docker containers

KUBE_ALLOW_PRIV="true"

修改yy2 kubelet的配置

CentOS7上没有docker.socket服务，注释掉kubelet中对docker.socket的依赖。

/usr/lib/systemd/system/kubelet.service

[Unit]

Description=Kubernetes Kubelet

#After=docker.socket cadvisor.service

After=cadvisor.service

#Requires=docker.socket cadvisor.service

Requires=cadvisor.service

启动yy2上的相关服务

minion上需要运行kube-proxy，kubelet以及docker。

for SERVICES in kube-proxy kubelet docker; do 
  systemctl restart $SERVICES
  systemctl enable $SERVICES
  systemctl status $SERVICES 
done

创建pod描述文件

创建一个apache的pod描述文件。

# cat apache.json

{

 "id": "apache",

 "desiredState": {

  "manifest": {

   "version": "v1beta1",

   "id": "apache-1",

   "containers": [{

    "name": "master",

    "image": "fedora/apache",

    "ports": [{

     "containerPort": 80,

     "hostPort": 80

    }]

   }]

  }

 },

 "labels": {

  "name": "apache"

 }

}

创建pod

通过客户端工具kubecfg提交任务给apiserver，由scheduler选择一个minion部署容。

[root@yy1 ~]# kubecfg -c apache.json create pods

I0925 06:43:26.768122 09313 request.go:292] Waiting for completion of /operations/1

ID         Image(s)      Host        Labels       Status

----------     ----------     ----------     ----------     ----------

apache       fedora/apache    /          name=apache     Waiting

 

[root@yy1 ~]# kubecfg list pods 

ID         Image(s)      Host        Labels       Status

----------     ----------     ----------     ----------     ----------

apache       fedora/apache    10.193.6.36/    name=apache     Waiting

apache服务会自动部署到机器yy2，yy2上的docker会自动下载image，然后启动apache服务。顺利的话，过一会儿，apache服务就会在yy2上起来。

[root@yy1 ~]# kubecfg list pods 

ID         Image(s)      Host        Labels       Status

----------     ----------     ----------     ----------     ----------

apache       fedora/apache    10.193.6.36/    name=apache     Running