CentOS7部署k8s集群
环境介绍及准备
操作系统采用Centos7.3 64位，细节如下：
[root@k8s-master ~]# uname -a
Linux k8s-master 3.10.0-327.el7.x86_64 #1 SMP Thu Nov 19 22:10:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
[root@k8s-master ~]# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)主机信息
本文准备了三台机器用于部署k8s的运行环境，细节如下：
节点及功能 | 主机名 | IP |
|---|---|---|
master、etcd、registry | k8s-master | 10.211.55.6 |
node1 | k8s-node-1 | 10.211.55.7 |
node2 | k8s-node-2 | 10.211.55.8 |
设置三台机器的主机名： master上执行：
1 | [root@localhost ~]# hostnamectl --static set-hostname k8s-master |
|---|
node1上执行：
1 | [root@localhost ~]# hostnamectl --static set-hostname k8s-node-1 |
|---|
node2上执行：
1 | [root@localhost ~]# hostnamectl --static set-hostname k8s-node-2 |
|---|
在三台机器上设置hosts，均执行如下命令：
echo '10.211.55.6 k8s-master
10.211.55.6 etcd
10.211.55.6 registry
10.211.55.7 k8s-node-1
10.211.55.8 k8s-node-2' >> /etc/hosts关闭三台机器上的防火墙
systemctl disable firewalld.service
systemctl stop firewalld.service部署etcd
k8s运行依赖etcd，需要先部署etcd，本文采用yum方式安装：
1 | # yum install -y etcd |
|---|
yum安装的etcd默认配置文件在/etc/etcd/etcd.conf。编辑配置文件，更改以下信息：
ETCD_NAME=master
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"
ETCD_ADVERTISE_CLIENT_URLS="http://etcd:2379,http://etcd:4001"启动并验证状态
# systemctl start etcd
# systemctl enable etcd
# etcdctl set testdir/testkey0 0
0
# etcdctl get testdir/testkey0
0
# etcdctl -C http://etcd:4001 cluster-health
member 8e9e05c52164694d is healthy: got healthy result from http://0.0.0.0:2379
cluster is healthy
# etcdctl -C http://etcd:2379 cluster-health
member 8e9e05c52164694d is healthy: got healthy result from http://0.0.0.0:2379
cluster is healthy扩展：Etcd集群部署参见——http://www.cnblogs.com/zhenyuyaodidiao/p/6237019.html
部署master
安装Docker
1 | [root@k8s-master ~]# yum install -y docker |
|---|
配置Docker配置文件
使其允许从registry中拉取镜像。增加如下一行： OPTIONS=‘–insecure-registry registry:5000’
[root@k8s-master ~]# vim /etc/sysconfig/docker
# /etc/sysconfig/docker
# Modify these options if you want to change the way the docker daemon runs
OPTIONS='--selinux-enabled --log-driver=journald --signature-verification=false'
if [ -z "${DOCKER_CERT_PATH}" ]; then
DOCKER_CERT_PATH=/etc/docker
fi
OPTIONS='--insecure-registry registry:5000'设置使用阿里云的docker加速器
cp -n /lib/systemd/system/docker.service /etc/systemd/system/docker.service
sed -i "s|ExecStart=/usr/bin/dockerd-current|ExecStart=/usr/bin/dockerd-current --registry-mirror=<your accelerate address>|g" /etc/systemd/system/docker.service
systemctl daemon-reload
systemctl restart docker.service设置开机自启动并开启服务
# systemctl enable docker.service
# systemctl restart docker.service安装kubernets
1 | [root@k8s-master ~]# yum install -y kubernetes |
|---|
搭建及运行registry
docker pull registry:2
// 将registry的数据卷与本地关联，便于管理和备份registry数据
docker run -d -p 5000:5000 --name registry -v /data/registry:/var/lib/registry registry:2
配置并启动kubernetes
在kubernetes master上需要运行以下组件：
- Kubernets API Server
- Kubernets Controller Manager
- Kubernets Scheduler
相应的要更改以下几个配置中带颜色部分信息：
修改/etc/kubernetes/apiserver
KUBE_API_ADDRESS=”–insecure-bind-address=0.0.0.0”
KUBE_API_PORT=”–port=8080”
KUBE_ETCD_SERVERS=”–etcd-servers=http://etcd:2379“
KUBE_ADMISSION_CONTROL=”–admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota”
修改/etc/kubernetes/config
1 | KUBE_MASTER="–master=http://k8s-master:8080" |
|---|
启动服务并设置开机自启动
# systemctl enable kube-apiserver.service
# systemctl start kube-apiserver.service
# systemctl enable kube-controller-manager.service
# systemctl start kube-controller-manager.service
# systemctl enable kube-scheduler.service
# systemctl start kube-scheduler.service部署node
安装docker
参见master的docker安装步骤
安装kubernets
参见master的kubernets安装步骤
配置并启动kubernetes
在kubernetes node上需要运行以下组件：
- Kubelet
- Kubernets Proxy
相应的要更改以下几个配置文中信息：
修改 /etc/kubernetes/config
1 | KUBE_MASTER="–master=http://k8s-master:8080" |
|---|
修改/etc/kubernetes/kubelet
KUBELET_ADDRESS="–address=0.0.0.0"
KUBELET_HOSTNAME="–hostname-override=k8s-node-1" (注意第二台要写 k8s-node-2)
KUBELET_API_SERVER="–api-servers=http://k8s-master:8080"启动服务并设置开机自启动
# systemctl enable kubelet.service
# systemctl start kubelet.service
# systemctl enable kube-proxy.service
# systemctl start kube-proxy.service
查看状态
在master上查看集群中节点及节点状态
# kubectl -s http://k8s-master:8080 get node
NAME STATUS AGE
k8s-node-1 Ready 3m
k8s-node-2 Ready 16s
# kubectl get nodes
NAME STATUS AGE
k8s-node-1 Ready 3m
k8s-node-2 Ready 43s至此，已经搭建了一个kubernetes集群。
创建Overlay网络——Flannel
安装Flannel
在master、node上均执行如下命令，进行安装
1 | # yum install -y flannel |
|---|
配置Flannel
master、node上均编辑/etc/sysconfig/flanneld，修改以下配置：
# etcd url location. Point this to the server where etcd runs
FLANNEL_ETCD_ENDPOINTS="http://etcd:2379"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" }'
{ "Network": "10.0.0.0/16" }启动
启动Flannel之后，需要依次重启docker、kubernete。 在master执行：
systemctl enable flanneld.service
systemctl start flanneld.service
service docker restart
systemctl restart kube-apiserver.service
systemctl restart kube-controller-manager.service
systemctl restart kube-scheduler.service在node上执行：
systemctl enable flanneld.service
systemctl start flanneld.service
service docker restart
systemctl restart kubelet.service
systemctl restart kube-proxy.service
Flannel网络
Flannel算是k8s里最简单的网络了，这里找到一篇文章可以帮忙理解Flannel网络。
测试
# docker pull nginx # 从外网registry拉一个nginx镜像过来
# docker tag nginx registry:5000/nginx # 为本地镜像打tag
# docker push registry:5000/nginx # 推送至本地registry
# docker rmi registry:5000/nginx # 删除本地镜像
cat << EOF >nginx.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx
spec:
replicas: 2
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: registry:5000/nginx
ports:
- containerPort: 80
resources:
requests:
cpu: 400m
EOF
# kubectl create -f nginx.yaml #创建nginx-dpmt部署
cat << EOF >nginx-svc.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx-svc
labels:
app: nginx-svc
spec:
type: NodePort
selector:
app: nginx
ports:
- port: 80
targetPort: 80
nodePort: 30088
EOF
# kubectl create -f nginx-svc.yaml # 创建nginx-svc服务
# kubectl describe service nginx-svc
Name: nginx-svc
Namespace: default
Labels: app=nginx-svc
Selector: app=nginx
Type: NodePort
IP: 10.254.53.185
Port: <unset> 80/TCP
NodePort: <unset> 30088/TCP
Endpoints: 10.0.19.2:80,10.0.4.2:80
Session Affinity: None
No events.
# curl http://k8s-node-1:30088/ # 通过nodePort测试nginx服务测试过程中遇到两个问题：
- pod服务一直处于 ContainerCreating状态，后来参考这里，安装了rhsm相关的包解决了。
nginx-svc.yaml文件中spec.selector.app的名称与nginx.yaml中的spec.template.metadata.labels.app不一致，这个导致一直无法通过NodePort访问服务。
参考
- http://qinghua.github.io/kubernetes-deployment/
- http://wdxtub.com/2017/06/05/k8s-note/
- https://jimmysong.io/kubernetes-handbook/guide/accessing-kubernetes-pods-from-outside-of-the-cluster.html
- http://tonybai.com/2017/01/17/understanding-flannel-network-for-kubernetes/
- http://www.cnblogs.com/puroc/p/6297851.html
- https://kubernetes.io/docs/tasks/run-application/run-stateless-application-deployment/