手记

Centos 安装K8s

溯水心生
2019-12-01 23:09:16浏览 1744

[TOC]

一、安装先决条件和集群规划

1.1 环境配置

以下操作在所有节点执行

  • 关闭防火墙：
 systemctl stop firewalld
 systemctl disable firewalld
  • 禁用SELinux ，让容器可以读取主机文件系统：

 setenforce 0
 sed -i 's/enforcing/disabled/' /etc/selinux/config
  • 校正时间：
 date
  • 安装ntp
yum install -y ntp
  • 同步时间
ntpdate cn.pool.ntp.org
  • 关闭swap K8S中不支持swap分区
swapoff -a

vim /etc/fstab
#/dev/mapper/centos-swap swap                    swap    defaults        0 0

1.2 集群规划

  • docker 版本： 19.03.5
  • kubelet 版本： V1.16.3
  • kubeadm 版本： v1.16.3
角色 主机名 IP 地址 配置信息
Master k8s-master 192.168.92.10 2核4G内存
Node k8s-slave01 192.168.92.11 2核4G内存
Node k8s-slave02 192.168.92.12 2核4G内存

以下操作在所有节点执行
更改hosts文件添加主机名与IP映射关系

vim /etc/hosts

192.168.92.10 k8s-master
192.169.92.11 k8s-slave01
192.168.92.12 k8s-slave02

将桥接的IPV4流量传递到iptables的链

cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
vm.swappiness = 0
net.ipv4.ip_forward= 1
EOF

载入配置：

sysctl --system

允许自动登录：

sed -i "s/PasswordAuthentication no/PasswordAuthentication yes/g" /etc/ssh/sshd_config

二、安装Docker

以下操作在所有节点执行

1.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

2.安装并运行Docker[使用存储库进行安装]

sudo yum install -y yum-utils \
  device-mapper-persistent-data \
  lvm2

3.设置稳定的存储库。

sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

4. 安装docker

sudo yum install docker-ce
sudo systemctl start docker
sudo systemctl enable docker

5.检查安装结果

# docker info

出现如下信息，则docker安装成功

Kernel Version: 3.10.0-693.17.1.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
Number of Docker Hooks: 3
CPUs: 1
Total Memory: 1.359 GiB
Name: localhost.localdomain
ID: KE6P:FAHI:ZYWT:AUWU:NVFG:6JRF:33ZS:AT4X:63QZ:ICYW:PUTO:V4ZB
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false
Registries: docker.io (secure)

三、安装kubeadm工具

以下操作所有节点进行

1.添加kerbernets镜像文件信息

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

2.安装kubeadm工具

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

2.设置开机自启动

systemctl enable kubelet && systemctl start kubelet

3.查看kubeadm、kubelet版本

 kubelet --version

 kubeadm version

三、安装master节点

以下步骤在主节点进行

1.初始化配置安装参数

kubeadm config print init-defaults > init.default.yaml

初始化结果如下：

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 1.2.3.4
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: localhost.localdomain
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: v1.16.0
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
scheduler: {}

2.下载kubernetes相关镜像

添加docker镜像仓库信息：


 echo '{"registry-mirrors":["https://registry.docker-cn.com"]}' > /etc/docker/daemon.json
 
 cat /etc/docker/daemon.json

重启docker容器

systemctl restart docker

修改初始化打印文件名为：init-config.yaml

mv init-default.yaml intit-config.yaml

修改init-config.yaml 文件，修改镜像地址信息：

imageRepository: registry.aliyuncs.com/google_containers

删除无用信息，最终配置文件如下，如多配置，会导致Master节点安装失败：


apiVersion: kubeadm.k8s.io/v1beta2
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.16.0
networking:
  serviceSubnet: 10.96.0.0/12
  podSubnet: 10.244.0.0/16

根据初始化的参数文件进行相关镜像下载：

kubeadm config images pull --config=init-config.yaml

根据下载的镜像安装Master

kubeeadm init --config=init-config.yaml

安装成功后会有如下类似提示：

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 192.168.92.10:6443 --token 4nmcwj.ebrnxqyks0rmkgki \
    --discovery-token-ca-cert-hash sha256:3d246361bc34b33cd7c60eb6a19e74a13842a4a810128b890c0f06c23065a28a

按提示操作：

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

此时查看雁阵kubeadm-config 的ConfigMap对象：

kubectl get -n kube-system configmap

查看安装状态：


[root@k8s-master k8s]# kubectl get nodes
NAME         STATUS     ROLES    AGE   VERSION
k8s-master   NotReady   master   17m   v1.16.3

四、安装CNI网络通信插件

1.安装CNI插件

此处采用kube-flannel

mkdir flannel && cd flannel
wget  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubekubectl apply -f kube-flannel.yml

flannel支持的模式：

flannel支持多种模型
     VxLAN  #vxLAN有以下两种模式
          (1) vxlan  #叠加网络或者隧道网络，通过封装网络报文的方式使不同网段的pod之间可以通讯
          (2) Directrouting #直接使用主机的IP地作为网关，通过主机路由的方式与目标pod进行通讯，当目标pod与当前pod不在同一三层网络内，会自动降级为VxLAN模式
    host-gw: Host GateWay #与VxLAN的Directrouting模式相同，当目标pod与当前pod不在同一三层网络内时，pod之间无法通讯
    UDP: #早期由于Linux内核不支持VxLAN，host-gw又有非常高的入门门槛，udp是flannel最早期使用的模式，由于使用普通的udp报文通讯，性能非常差，在可以使用前面两种模式的情况下请勿使用该模式

查看集群状态：


[root@k8s-master flannel]# kubectl get nodes
NAME         STATUS   ROLES    AGE     VERSION
k8s-master   Ready    master   5m43s   v1.16.3

TIPS:

  • 如果master安装失败,执行
kubeadm reset   #重置主机，之后重新执行kubeadm init再次安装
  • 如果 Pod 错误，需要执行
kubectl --namespace=kube-system describe pod <pod_name>

五、node节点加入集群

先决条件： 已经安装kubelet kubeadm

1.创建节点加入配置文件 join-config.yaml

vim /home/k8s/join-config.yaml

apiVersion: kubeadm.k8s.io/v1beta2
kind: JoinConfiguration
discovery:
  bootstrapToken:
    apiServerEndpoint: 192.168.92.10:6443
    token: 4nmcwj.ebrnxqyks0rmkgki
    unsafeSkipCAVerification: true
  tlsBootstrapToken: 4nmcwj.ebrnxqyks0rmkgki

其中 token 和 tlsBootstrapToken 来自Master安装后的提示末尾信息, 如果忘记了token信息和证书信息可使用以下命令查询：

  • 查询token信息
kubeadm token list

token 24小时失效
可使用如下命令重新创建

kubeadm token create
  • 查询ca证书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/^.* //'

2.node节点加入集群

以下操作适用于node1和node2

kubeadm join --config=join-config.yaml

节点加入成功会有如下信息：


[preflight] Running pre-flight checks
        [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
        [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.5. Latest validated version: 18.09
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.16" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Activating the kubelet service
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

如果节点加入超时，请执行如下命令：

swapoff -a
kubeadm reset
systemctl daemon-reload
systemctl restart kubelet

节点剔除：

kubectl drain k8s-slave2 --delete-local-data --ignore-daemonsets

kubectl delete node k8s-slave2

六、常用命令：

1.查看所加入节点


[root@k8s-master kubernetes]# kubectl get nodes
NAME         STATUS   ROLES    AGE    VERSION
k8s-master   Ready    master   101m   v1.16.3
k8s-slave1   Ready    <none>   41s    v1.16.3
k8s-slave2   Ready    <none>   11m    v1.16.3

2.查看所有Pod命令

kubectl get pod --all-namespaces

本文由博客一文多发平台 OpenWrite 发布！

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Docker
Kubernetes
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