centos7使用kubeadm搭建一个k8s集群

简介

kubeadm默认情况下并不会安装一个网络解决方案，所以用kubeadm安装完之后，需要自己来安装一个网络的插件。

部署

系统环境（准备工作）

各节点安装docker

此处不重复说明，详细安装步骤参考我另一篇博客 点此跳转

首先关闭selinux防火墙

vim /etc/sysconfig/selinux

把SELINUX改成disabled，然后保存退出。

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
#     targeted - Targeted processes are protected,
#     minimum - Modification of targeted policy. Only selected processes are protected. 
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted

关闭防火墙

# systemctl stop firewalld.service
# systemctl disable firewalld.service

禁用swap

关闭

swapoff -a

同时禁用

vim /etc/fstab

注释掉swap那行

#
# /etc/fstab
# Created by anaconda on Sun May 12 23:11:33 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root /                       xfs     defaults        0 0
UUID=3755b261-d764-45cd-8806-f82c2aa7eb12 /boot                   xfs     defaults        0 0
/dev/mapper/centos-home /home                   xfs     defaults        0 0
#/dev/mapper/centos-swap swap                    swap    defaults        0 0

查看swap使用确认关闭

free m

修改hosts文件 对应两台物理机

修改hosts

# vim /etc/hosts

添加映射（对应master节点和node节点）

192.168.1.223  k8s-master
192.168.1.50  node1

网络设置

k8s在RHEL/CentOS 7 系统上可能会路由失败，我们需要设置一下：

# vim /etc/sysctl.d/k8s.conf

修改为

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1

并使它生效

# sysctl -p /etc/sysctl.d/k8s.conf

安装kubeadm

配置文件

安装kubeadm,kubelet和kubectl时因为需要访问google的库下载镜像源，我们这里设置一下访问阿里云的库

# vim /etc/yum.repos.d/kubernetes.repo

修改为

[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg

安装指定版本

# yum install -y kubelet-1.14.2 kubeadm-1.14.2 kubectl-v1.14.2
# systemctl enable kubelet && systemctl start kubelet

使用kubeadm初始化master节点

注意：国内网络环境需添加 --image-repository registry.aliyuncs.com/google_containers 下载需要的包源，也可以自行下载包源离线安装

这里我们用的是阿里云镜像的k8s包源

# kubeadm init --kubernetes-version=v1.14.1 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.1.223 --image-repository registry.aliyuncs.com/google_containers

初始化成功

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.223:6443 --token dlceft.lcix67fmvte12o8g \
    --discovery-token-ca-cert-hash sha256:f0c3e0eb01b861d5db32bf5475a047eff720c021598aa4889e9fb4eb0aafb1c5

通过上面成功的提示可以看到，要开始使用集群，还需要一些配置

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

最下面的这行kubeadm join 是在子节点操作加入集群的方法，后面的sha256是kubenetes的token值，这个值默认为24小时有效时间，如果有需要可以自行百度配置永久token

# kubeadm join 192.168.1.223:6443 --token dlceft.lcix67fmvte12o8g \
	    --discovery-token-ca-cert-hash sha256:f0c3e0eb01b861d5db32bf5475a047eff720c021598aa4889e9fb4eb0aafb1c5

完成以上步骤后测试看一下

# kubectl get pods --all-namespaces

结果是

NAMESPACE     NAME                                 READY   STATUS             RESTARTS   AGE
kube-system   coredns-8686dcc4fd-h746r             0/1     CrashLoopBackOff   6          8m45s
kube-system   coredns-8686dcc4fd-qm27q             0/1     CrashLoopBackOff   6          8m45s
kube-system   etcd-k8s-master                      1/1     Running            0          7m47s
kube-system   kube-apiserver-k8s-master            1/1     Running            0          8m4s
kube-system   kube-controller-manager-k8s-master   1/1     Running            0          8m6s
kube-system   kube-proxy-h2zgr                     1/1     Running            0          8m45s
kube-system   kube-scheduler-k8s-master            1/1     Running            0          7m54s

可以看到coredns是没启动起来的，这是因为我们还没有安装network addon，部署k8s集群是不会帮你配置默认网络的，所以我们要安装一个network addon，kubeadm只支持CNI-based networks（不支持kubenet）

配置CNI

常见的network addon有很多 这里我们用Flannel，获取配置文件

# wget https://raw.githubusercontent.com/coreos/flannel/v0.10.0/Documentation/kube-flannel.yml

然后配置网络

# kubectl apply -f kube-flannel.yml

如果需要删除

# kubectl delete -f kube-flannel.yml

加入node节点

现在我们开始加入一些k8s节点到集群中
连接到我们的节点上，执行刚才kubeadm init时的最后一行，这行命令每个人都不一样，上面提到token值每个人不一样。
如果没记录下这里的token可以通过

生成一条永久token

# kubeadm token create --ttl 0

得到

m3gmnd.zg9pb04b5x53kjvw

查看所有token

# kubeadm token list

得到

	TOKEN                     TTL         EXPIRES                     USAGES                   DESCRIPTION                                                EXTRA GROUPS
fhwj8c.uhry37dwbxcfc742   20h         2019-06-11T23:20:46-04:00   authentication,signing   <none>                                                     system:bootstrappers:kubeadm:default-node-token
m3gmnd.zg9pb04b5x53kjvw   <forever>   <never>                     authentication,signing   <none>                                                     system:bootstrappers:kubeadm:default-node-token
sn4x0i.8f8nfxjw6wtpzq9x   19h         2019-06-11T22:43:52-04:00   authentication,signing   The default bootstrap token generated by 'kubeadm init'.   system:bootstrappers:kubeadm:default-node-token

获取ca证书sha256编码hash值

openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'

得到

929bd928ae4ee3c8bbbe1c911e920f0411c005892a8f18d1947171b8e391b8c3

最后node节点中执行

# kubeadm join 192.168.1.223:6443 --token dlceft.lcix67fmvte12o8g \
    --discovery-token-ca-cert-hash sha256:f0c3e0eb01b861d5db32bf5475a047eff720c021598aa4889e9fb4eb0aafb1c5

然后我们回到master节点看一下node添加成没成功

# kubectl get nodes

可以看到node已经成功添加

NAME         STATUS     ROLES    AGE   VERSION
k8s-master   Ready      master   35m   v1.14.2
k8s1         NotReady   <none>   12s   v1.14.1

以上为阿里云在线安装

网上找的离线安装：https://blog.51cto.com/daisywei/2105877