接着上一篇的介绍完核心概念后，尝试下搭建k8s的集群，准备了六台虚拟机用于部署k8s的运行环境。

一. 环境准备及虚拟机信息

1. 虚拟机环境

2. 六台虚机信息（自行配置 /etc/hosts 文件）

节点功能	主机名	IP
master1、etcd1	master1	192.168.8.224
master2、etcd2	master2	192.168.8.225
master3、etcd3	master3	192.168.8.226
node1	node1	192.168.8.227
node2	node2	192.168.8.228
node3	node3	192.168.8.229

3. 关闭六台虚机的防火墙：

systemctl disable firewalld
systemctl stop firewalld

二. etcd集群搭建

1. 安装etcd

yum install etcd -y

2. 配置etcd

yum安装的etcd默认配置文件在/etc/etcd/etcd.conf，以下将三个节点上的配置贴出来，请注意不同点。

2379是默认的使用端口，为了防止端口占用问题的出现，增加4001端口备用。

master1 ：

# [member]
ETCD_NAME=etcd1
ETCD_DATA_DIR="/var/lib/etcd/test.etcd"
#ETCD_WAL_DIR=""
#ETCD_SNAPSHOT_COUNT="10000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
#ETCD_CORS=""
#
#[cluster]
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://master1:2380"
# if you use different ETCD_NAME (e.g. test), set ETCD_INITIAL_CLUSTER value for this name, i.e. "test=http://..."
ETCD_INITIAL_CLUSTER="etcd1=http://master1:2380,etcd2=http://master2:2380,etcd3=http://master3:2380"
ETCD_INITIAL_CLUSTER_STATE="new"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster-baby"
ETCD_ADVERTISE_CLIENT_URLS="http://master1:2379,http://master1:4001"

master2 ：

# [member]
ETCD_NAME=etcd2
ETCD_DATA_DIR="/var/lib/etcd/test.etcd"
#ETCD_WAL_DIR=""
#ETCD_SNAPSHOT_COUNT="10000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
#ETCD_CORS=""
#
#[cluster]
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://master2:2380"
# if you use different ETCD_NAME (e.g. test), set ETCD_INITIAL_CLUSTER value for this name, i.e. "test=http://..."
ETCD_INITIAL_CLUSTER="etcd1=http://master1:2380,etcd2=http://master2:2380,etcd3=http://master3:2380"
ETCD_INITIAL_CLUSTER_STATE="new"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster-baby"
ETCD_ADVERTISE_CLIENT_URLS="http://master2:2379,http://master2:4001"

master3 ：

# [member]
ETCD_NAME=etcd3
ETCD_DATA_DIR="/var/lib/etcd/test.etcd"
#ETCD_WAL_DIR=""
#ETCD_SNAPSHOT_COUNT="10000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
#ETCD_CORS=""
#
#[cluster]
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://master3:2380"
# if you use different ETCD_NAME (e.g. test), set ETCD_INITIAL_CLUSTER value for this name, i.e. "test=http://..."
ETCD_INITIAL_CLUSTER="etcd1=http://master1:2380,etcd2=http://master2:2380,etcd3=http://master3:2380"
ETCD_INITIAL_CLUSTER_STATE="new"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster-baby"
ETCD_ADVERTISE_CLIENT_URLS="http://master3:2379,http://master3:4001"

修改好以上配置后，在各个节点上启动etcd服务，并验证集群状态：

systemctl start etcd
systemctl enable etcd
etcdctl -C http://etcd:2379 cluster-health
etcdctl -C http://etcd:4001 cluster-health

集群状态没问题后可继续操作：

三. 部署 master

1. 安装 docker ，设置开机自启动并开启服务

yum install docker -y
chkconfig docker on
service docker start

2. 安装 kubernetes 

yum install kubernetes -y

在 master 的虚机上，需要运行三个组件： Kubernets API Server、 Kubernets Controller Manager、 Kubernets Scheduler。
首先修改  /etc/kubernetes/apiserver 文件：

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

# The address on the local server to listen to.
KUBE_API_ADDRESS="--insecure-bind-address=0.0.0.0"

# The port on the local server to listen on.
KUBE_API_PORT="--port=8080"

# Port minions listen on
# KUBELET_PORT="--kubelet-port=10250"

# Comma separated list of nodes in the etcd cluster
KUBE_ETCD_SERVERS="--etcd-servers=http://etcd:2379"

# Address range to use for services
KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"

# default admission control policies
# KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota"
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota"

# Add your own!
KUBE_API_ARGS=""

接着修改  /etc/kubernetes/config  文件：（最后一句 masterX:8080 ，对应master1/2/3机器就好）

###
# kubernetes system config
#
# The following values are used to configure various aspects of all
# kubernetes services, including
#
#   kube-apiserver.service
#   kube-controller-manager.service
#   kube-scheduler.service
#   kubelet.service
#   kube-proxy.service
# logging to stderr means we get it in the systemd journal
KUBE_LOGTOSTDERR="--logtostderr=true"

# journal message level, 0 is debug
KUBE_LOG_LEVEL="--v=0"

# Should this cluster be allowed to run privileged docker containers
KUBE_ALLOW_PRIV="--allow-privileged=false"

# How the controller-manager, scheduler, and proxy find the apiserver
KUBE_MASTER="--master=http://master1:8080"

修改完成后，启动服务并设置开机自启动即可：

systemctl enable kube-apiserver
systemctl start kube-apiserver
systemctl enable kube-controller-manager
systemctl start kube-controller-manager
systemctl enable kube-scheduler
systemctl start kube-scheduler

四. 部署 node

1. 安装 docker ，设置开机自启动并开启服务

yum install docker -y
chkconfig docker on
service docker start

2. 安装 kubernetes 

yum install kubernetes -y

在 node 的虚机上，需要运行三个组件： Kubelet、 Kubernets Proxy。
首先修改  /etc/kubernetes/config 文件：（注意：这里配置的是etcd的地址，也就是master1/2/3的地址其中之一）

###
# kubernetes system config
#
# The following values are used to configure various aspects of all
# kubernetes services, including
#
#   kube-apiserver.service
#   kube-controller-manager.service
#   kube-scheduler.service
#   kubelet.service
#   kube-proxy.service
# logging to stderr means we get it in the systemd journal
KUBE_LOGTOSTDERR="--logtostderr=true"

# journal message level, 0 is debug
KUBE_LOG_LEVEL="--v=0"

# Should this cluster be allowed to run privileged docker containers
KUBE_ALLOW_PRIV="--allow-privileged=false"

# How the controller-manager, scheduler, and proxy find the apiserver
KUBE_MASTER="--master=http://etcd:8080"

接着修改 /etc/kubernetes/kubelet 文件：（注：--hostname-override= 对应的node机器）

###
# kubernetes kubelet (minion) config

# The address for the info server to serve on (set to 0.0.0.0 or "" for all interfaces)
KUBELET_ADDRESS="--address=0.0.0.0"

# The port for the info server to serve on
# KUBELET_PORT="--port=10250"

# You may leave this blank to use the actual hostname
KUBELET_HOSTNAME="--hostname-override=node1"

# location of the api-server
KUBELET_API_SERVER="--api-servers=http://etcd:8080"

# pod infrastructure container
KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=registry.access.redhat.com/rhel7/pod-infrastructure:latest"

# Add your own!
KUBELET_ARGS=""

修改完成后，启动服务并设置开机自启动即可：

systemctl enable kubelet
systemctl start kubelet
systemctl enable kube-proxy
systemctl start kube-proxy

3. 查看集群状态

在任意一台master上查看集群中节点及节点状态：

kubectl get node

至此，已经搭建了一个kubernetes集群了，但目前该集群还不能很好的工作，因为需要对集群中pod的网络进行统一管理。

五. 创建覆盖网络 flannel

1. 在master、node上均执行如下命令，安装 flannel

yum install flannel -y

2. 在master、node上均编辑 /etc/sysconfig/flanneld 文件

# Flanneld configuration options  

# etcd url location.  Point this to the server where etcd runs
FLANNEL_ETCD_ENDPOINTS="http://etcd:2379"

# etcd config key.  This is the configuration key that flannel queries
# For address range assignment
FLANNEL_ETCD_PREFIX="/atomic.io/network"

# Any additional options that you want to pass
#FLANNEL_OPTIONS=""

3. 配置etcd中关于flannel的key

flannel使用etcd进行配置，来保证多个flannel实例之间的配置一致性，所以需要在etcd上进行如下配置：

etcdctl mk /atomic.io/network/config '{ "Network": "10.0.0.0/16" }'

（‘/atomic.io/network/config’这个key与上文/etc/sysconfig/flannel中的配置项FLANNEL_ETCD_PREFIX是相对应的，错误的话启动就会出错）

4. 启动修改后的 flannel ，并依次重启docker、kubernete

在 master 虚机上执行：

systemctl enable flanneld
systemctl start flanneld
service docker restart
systemctl restart kube-apiserver
systemctl restart kube-controller-manager
systemctl restart kube-scheduler

在  node 虚机上执行：

systemctl enable flanneld
systemctl start flanneld
service docker restart
systemctl restart kubelet
systemctl restart kube-proxy

参考：

Centos7下Etcd集群搭建：http://www.cnblogs.com/zhenyuyaodidiao/p/6237019.html

Centos7部署Kubernetes集群：http://www.cnblogs.com/zhenyuyaodidiao/p/6500830.html

Docker网络及flannel介绍：http://blog.csdn.net/zhaoguoguang/article/details/51161957