使用Kubeadm安装K8S

环境准备

• 机器信息

  # 实验机器均为centos7.9系统，1主3从。
  # 每个机器均为4核CPU 4G内存
  # 注意：cpu和内存太低k8s会起不来。最低好像是2核CPU 2G内存。
  master	10.0.0.170
  node01	10.0.0.171
  node02	10.0.0.172
  node03	10.0.0.173
  

• ssh key验证（非必须，为了方便）

  # 使用下面的脚本实现
  
  #!/bin/bash
  #
  #********************************************************************
  #Author:            Wuvikr
  #QQ:                744123155
  #Date:              2020-10-29
  #FileName           ssh_auth_each_other.sh
  #URL:               http://www.wuvikr.com
  #Description        The test script
  #Copyright (C):     2020 All rights reserved
  #********************************************************************
  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
  export PATH
  
  IPLIST="
  10.0.0.171
  10.0.0.172
  10.0.0.173
  "
  
  export SSHPASS=744123
  
  PASS=744123
  
  rpm -q sshpass &> /dev/null || yum -y install sshpass &> /dev/null
  rpm -q expect &> /dev/null || yum -y install expect &> /dev/null
  
  [ -f /root/.ssh/id_rsa ] || ssh-keygen -t rsa -P '' -f /root/.ssh/id_rsa &> /dev/null
  
  sshpass -e ssh-copy-id -o StrictHostKeyChecking=no 127.0.0.1 > /dev/null
  
  for IP in $IPLIST
  do
  expect &> /dev/null <<EOF
  set timeout 20
  spawn scp -rp /root/.ssh/ ${IP}:/root/
  expect {
        "yes/no" { send "yes
  ";exp_continue }
        "password" { send "${PASS}
  " }
  }
  expect eof
  EOF
  echo -e "\e[1;32m${IP}:免密登录设置成功！\e[0m"
  done
  

• 修改hosts文件

  # 在主节点修改hosts文件
  # 将主和从的信息都加入进去
  127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
  ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
  10.0.0.170  master.k8s master kubeapi.k8s
  10.0.0.171  node01.k8s node01
  10.0.0.172  node02.k8s node02
  10.0.0.173  node03.k8s node03 
  
  # 拷贝到其他从节点上去
  scp /etc/hosts node01:/etc/hosts
  scp /etc/hosts node02:/etc/hosts
  scp /etc/hosts node03:/etc/hosts
  

• 禁用防火墙和SELINUX

  systemctl disable --now firewalld
  
  sed -i.bak 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
  

• 关闭swap

  swapoff -a
  
  sed -ri 's/(.*swap.*)/#1/' /etc/fstab
  

• 时间同步

  yum install -y chrony
  
  systemctl enable --now chronyd
  
  # 这里使用了阿里和腾讯的时间服务器
  ntp1.aliyun.com
  ntp2.aliyun.com
  time1.cloud.tencent.com
  time2.cloud.tencent.com
  
  [root@master ~]#chronyc sources
  210 Number of sources = 4
  MS Name/IP address         Stratum Poll Reach LastRx Last sample               
  ===============================================================================
  ^* 120.25.115.20                 2   7   377   145    +17ms[+9805us] +/-   36ms
  ^+ 203.107.6.88                  2   6   377   406    +15ms[  -11ms] +/-   32ms
  ^+ 139.199.215.251               2   7   367   143    +14ms[  +14ms] +/-   52ms
  ^+ 111.230.189.174               2   7   377   146    +16ms[+9570us] +/-   56ms
  
  

安装Docker

# Centos7安装Docker脚本

#!/bin/bash
#
#********************************************************************
#Author:            Wuvikr
#QQ:                744123155
#Date:              2020-12-01
#FileName           docker_install_for_centos7.sh
#URL:               http://www.wuvikr.top
#Description        The test script
#Copyright (C):     2020 All rights reserved
#********************************************************************
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

Version="19.03.13-3.el7"

# 下载docker安装源
wget -P /etc/yum.repos.d/ https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

# 安装docker
yum -y install docker-ce-$Version docker-ce-cli-$Version || echo -e '33[1;31m安装失败，请检查网络和yum源配置！33[0m'

# 使用国内镜像加速
# 阿里云（需要登录账号分配地址）
# 网易云 https://vgunv6qp.mirror.aliyuncs.com
# 腾讯云 https://mirror.ccs.tencentyun.com
# 中科大 https://docker.mirrors.ustc.edu.cn
# docker中国 https://registry.docker-cn.com
# 这里顺便修改下CGROUP驱动
mkdir -p /etc/docker
tee /etc/docker/daemon.json <<-'EOF'
{
	"exec-opts": ["native.cgroupdriver=systemd"],
    "registry-mirrors": [
        "https://mirror.ccs.tencentyun.com",
        "https://docker.mirrors.ustc.edu.cn",
        "https://registry.docker-cn.com"
    ]
}
EOF

# 重新加载配置并启动docker
systemctl daemon-reload
systemctl enable --now docker

docker version && echo -e "33[1;32m${Version}安装成功！33[0m" || echo -e '33[1;31m安装失败！33[0m'

安装k8s

• centos

# 使用阿里云的yum源
cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[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
EOF

# 有梯子的朋友可以试试google官网源
cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
        https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF

# 安装kubuadm并启动
yum install -y kubelet kubeadm kubectl
systemctl enable --now kubelet

• ubuntu

apt update
curl -s https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | sudo apt-key add -

tee /etc/apt/sources.list.d/kubernetes.list <<EOF 
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
EOF

apt update
apt install -y kubelet kubeadm kubectl
systemctl enable kubelet

初始化集群

只需要在主节点上执行此步骤

1. 方法一：使用命令行配置初始化（较简单，未指定的使用默认设定）

# 初始化命令
kubeadm init --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.19.4 --control-plane-endpoint kubeapi.k8s --apiserver-advertise-address 10.0.0.170 --pod-network-cidr 10.244.0.0/16


# 说明
--image-repository ：			指定镜像源
--kubernetes-version：			指定K8S版本，最好和安装的kubeadm保持一致
--control-plane-endpoint：		指定control-plane的IP或DNS名称
--apiserver-advertise-address：	指定API服务器的IP地址
--pod-network-cidr：				指定Pod网络的IP网段

2. 方法二：使用配置文件初始化（可以具体的设置想要修改的参数）

# 生成默认初始化配置文件
kubeadm config print init-defaults > kubeadm.yaml

# 生成默认初始化配置文件后可以按需进行修改
cat kubeadm.yaml

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s	# token令牌的过期时间
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 10.0.0.170  # apiserver节点IP
  bindPort: 6443	# 默认端口
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: master.k8s  # 默认使用当前master节点的hostname
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki  # 各种证书路径
clusterName: kubernetes		# 集群名称
controllerManager: {}
dns:
  type: CoreDNS	# 默认使用CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd # etcd目录
imageRepository: registry.aliyuncs.com/google_containers  # 改为阿里云镜像源
kind: ClusterConfiguration
kubernetesVersion: v1.19.4		# K8S版本
networking:
  dnsDomain: cluster.local
  podSubnet: 10.244.0.0/16  # Pod网络的IP网段，这里使用flannel插件的网段
  serviceSubnet: 10.96.0.0/12 # service网络的网段地址
scheduler: {}

# 使用预先配置好的文件进行初始化
kubeadm init --config kubeadm.yaml

出现以下内容即表示初始化成功，然后按照提示进行操作

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/

You can now join any number of control-plane nodes by copying certificate authorities
and service account keys on each node and then running the following as root:

  kubeadm join kubeapi.k8s:6443 --token onlo0f.5mio4k9d2o5xs0tt 
    --discovery-token-ca-cert-hash sha256:1d58267976a4f9e61858d217599e70305796ef129708b02c07c6eb38763a9885 
    --control-plane 

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

kubeadm join kubeapi.k8s:6443 --token onlo0f.5mio4k9d2o5xs0tt 
    --discovery-token-ca-cert-hash sha256:1d58267976a4f9e61858d217599e70305796ef129708b02c07c6eb38763a9885 
    
    
# 拷贝kubeconfig文件到当前用户的家目录下
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# 配置网络插件，这里是用flannel，如果修改了pod网段，需要在flannel配置文件中也做相应修改。
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f kube-flannel.yml

# 添加子节点到集群
# 在子节点上执行如下命令
kubeadm join kubeapi.k8s:6443 --token onlo0f.5mio4k9d2o5xs0tt 
    --discovery-token-ca-cert-hash sha256:1d58267976a4f9e61858d217599e70305796ef129708b02c07c6eb38763a9885 
    
# 注意：令牌有时间限制，经过一段时间会过期
## 可以在初始化的时候使用 --token-ttl duration 参数指定令牌过期时间，默认为24h。
## 令牌过期后可以使用命令 kubeadm token create --print-join-command 重新获取。

# 使用kubectl get nodes 查看节点状况

相关报错解决

# 初始化预检测阶段可能会出现以下错误
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR FileContent--proc-sys-net-bridge-bridge-nf-call-iptables]: /proc/sys/net/bridge/bridge-nf-call-iptables contents are not set to 1
	[ERROR FileContent--proc-sys-net-ipv4-ip_forward]: /proc/sys/net/ipv4/ip_forward contents are not set to 1

# 解决方法
cat > /etc/sysctl.d/k8s.conf <<EOF
> net.bridge.bridge-nf-call-iptables = 1
> net.bridge.bridge-nf-call-ip6tables = 1
> net.ipv4.ip_forward = 1
> EOF

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

查看集群状况

# 查看Pod运行状态
[root@master ~]#kubectl get pods -n kube-system
NAME                                 READY   STATUS    RESTARTS   AGE
coredns-6d56c8448f-nv28f             1/1     Running   0          4m59s
coredns-6d56c8448f-qwkhr             1/1     Running   0          4m59s
etcd-master.k8s                      1/1     Running   0          5m17s
kube-apiserver-master.k8s            1/1     Running   0          5m17s
kube-controller-manager-master.k8s   1/1     Running   0          5m17s
kube-flannel-ds-cts45                1/1     Running   0          2m25s
kube-flannel-ds-jql5t                1/1     Running   0          88s
kube-flannel-ds-m522q                1/1     Running   0          4m
kube-flannel-ds-vwcp8                1/1     Running   0          91s
kube-proxy-dw5fq                     1/1     Running   0          91s
kube-proxy-fnxch                     1/1     Running   0          2m25s
kube-proxy-g9c77                     1/1     Running   0          88s
kube-proxy-gdb25                     1/1     Running   0          5m
kube-scheduler-master.k8s            1/1     Running   0          5m17s

# 查看节点状况
[root@master ~]#kubectl get nodes
NAME         STATUS   ROLES    AGE     VERSION
master.k8s   Ready    master   5m25s   v1.19.4
node01.k8s   Ready    <none>   2m31s   v1.19.4
node02.k8s   Ready    <none>   98s     v1.19.4
node03.k8s   Ready    <none>   94s     v1.19.4

## 可能有些pod是Init状态，node是NotReady状态，不要着急，多等待一会即可。
## 到这里k8s的安装就算是初步完成了