Centos 使用 kubeadm 部署 kubernetes


使用 kubeadm 部署 kubernetes

集群介绍:

  • master:CentOS7、10.69.12.136
  • node1:CentOS7、10.69.12.235
  • node2:CentOS7、10.70.147.141

本教程使用的用户均为 root

安装 Docker

此部分需要在 master 和 node 上都执行。

卸载旧版本:

$ sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine

添加 yum 软件源:

$ sudo yum-config-manager \
    --add-repo \
    https://mirrors.ustc.edu.cn/docker-ce/linux/centos/docker-ce.repo

$ sudo sed -i 's/download.docker.com/mirrors.ustc.edu.cn\/docker-ce/g' /etc/yum.repos.d/docker-ce.repo

安装 Docker CE

$ sudo yum makecache fast
$ sudo yum install docker-ce

启动 Docker CE

$ sudo systemctl enable docker
$ sudo systemctl start docker

安装 kubelet kubeadm kubectl

此部分需要在 master 和 node 上都执行。

$ cat <<EOF | sudo tee /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

$ sudo yum install -y kubelet kubeadm kubectl

修改内核的运行参数:

$ cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

# 应用配置
$ sysctl --system

配置 kubelet:

# /etc/systemd/system/kubelet.service.d/文件夹不存在则自行创建
$ vi /etc/systemd/system/kubelet.service.d/10-proxy-ipvs.conf

写如如下内容:

[Service]
ExecStartPre=-modprobe ip_vs
ExecStartPre=-modprobe ip_vs_rr
ExecStartPre=-modprobe ip_vs_wrr
ExecStartPre=-modprobe ip_vs_sh

执行以下命令应用配置。

$ sudo systemctl daemon-reload

查看 Kubernetes 运行状态:

$ systemctl status kubelet

假如出现如下的信息表示并没有正常运行:

● kubelet.service - kubelet: The Kubernetes Node Agent
   Loaded: loaded (/usr/lib/systemd/system/kubelet.service; disabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/kubelet.service.d
           └─10-kubeadm.conf
        /etc/systemd/system/kubelet.service.d
           └─10-proxy-ipvs.conf
   Active: activating (auto-restart) (Result: exit-code) since 日 2020-06-14 07:50:25 EDT; 1s ago
     Docs: https://kubernetes.io/docs/
  Process: 61400 ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS (code=exited, status=255)
 Main PID: 61400 (code=exited, status=255)

可以执行如下的命令查看具体的错误信息:

$ journalctl -xefu kubelet

查看systemd日志发现真正的错误原因是:

failed to run Kubelet: Running with swap on is not supported, please disable swap! or set --fail-swap-on flag to false

运行如下的命令检查 Swap 有没有被关闭

$ cat /proc/swaps

禁用Swap命令如下:

# 关闭Swap,机器重启后不生效
$ swapoff -a

# 修改/etc/fstab永久关闭Swap
$ cp -p /etc/fstab /etc/fstab.bak$(date '+%Y%m%d%H%M%S')
# CentOS
$ sed -i "s/\/dev\/mapper\/centos-swap/\#\/dev\/mapper\/centos-swap/g" /etc/fstab
# 修改后重新挂载全部挂载点
$ mount -a

# 查看Swap
$ free -m
$ cat /proc/swaps

运行下面命令重启Kubelet:

$ systemctl daemon-reload
$ systemctl restart kubelet

再次查看 Kubernetes 运行状态:

$ systemctl status kubelet

正常启动则可以执行后续的操作:

● kubelet.service - kubelet: The Kubernetes Node Agent
   Loaded: loaded (/usr/lib/systemd/system/kubelet.service; disabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/kubelet.service.d
           └─10-kubeadm.conf
        /etc/systemd/system/kubelet.service.d
           └─10-proxy-ipvs.conf
   Active: active (running) since 日 2020-06-14 07:57:54 EDT; 146ms ago
     Docs: https://kubernetes.io/docs/
 Main PID: 64249 (kubelet)
    Tasks: 9
   Memory: 15.3M
   CGroup: /system.slice/kubelet.service
           └─64249 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/con...

集群部署

master部署

在 master 节点执行如下的命令:

$ sudo kubeadm init --image-repository registry.cn-hangzhou.aliyuncs.com/google_containers \
      --pod-network-cidr 10.244.0.0/16 \
      --v 5 \
      --ignore-preflight-errors=all
  • –pod-network-cidr 10.244.0.0/16 参数与后续 CNI 插件有关,这里以 flannel 为例,若后续部署其他类型的网络插件请更改此参数。

正常执行会输出:

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 10.69.12.136:6443 --token agu552.wz67ri0qqrwos1hm \
    --discovery-token-ca-cert-hash sha256:c7e9a4e221d1a1ca27b7ccfab09ada62eb6a55d78bd6b737f339c63e7ecb1724 

保留上面加入集群的命令,在后续 node 节点中要使用.

配置 flannel:

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.11.0/Documentation/kube-flannel.yml

关闭防火墙:

# 查看防火墙状态
$ firewall-cmd --state

# 停止firewall
$ systemctl stop firewalld.service

# 禁止firewall开机启动
$ systemctl disable firewalld.service 

node部署

在 node 节点中执行刚才 mater 中提示的加入集群的命令:

kubeadm join 10.69.12.136:6443 --token agu552.wz67ri0qqrwos1hm \
    --discovery-token-ca-cert-hash sha256:c7e9a4e221d1a1ca27b7ccfab09ada62eb6a55d78bd6b737f339c63e7ecb1724 

使用

将 /etc/kubernetes/admin.conf 复制到 ~/.kube/config

# ~/.kube/文件夹不存在则创建
$ cp /etc/kubernetes/admin.conf ~/.kube/config

查看启动的服务

$ kubectl get all -A 

查看集群中的节点

$ kubectl get node

参考文献