Kubeadm安装K8s集群

一、硬件环境

• 准备3台Linux服务器，此处用Vmware虚拟机。

主机名	CPU	内存
k8smaster	2核	4G
k8snode1	2核	4G
k8snode2	2核	4G

二、系统前置准备

• 配置三台主机的hosts文件

cat << EOF > /etc/hosts
192.168.240.130 k8smaster
192.168.240.132 k8snode1
192.168.240.133 k8snode2
EOF

• 设置主机名

hostnamectl set-hostname k8smaster
hostnamectl set-hostname k8snode1
hostnamectl set-hostname k8snode2

• 关闭selinux、禁用swap分区

sed -i 's/enforcing/disabled/' /etc/selinux/config 
setenforce 0

swapoff -a
sed -ri 's/.*swap.*/#&/' /etc/fstab

• ipv4流量转发

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

#让配置文件生效
modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf

• 关闭防火墙

systemctl disable firewalld && systemctl stop firewalld

• 同步三台服务器的时间

yum install ntpdate -y
ntpdate time.windows.com

三、环境安装

Docker 安装

• Docker卸载

systemctl stop docker 
yum remove -y docker-ce docker-ce-cli containerd.io
rm -rf /var/lib/docker
rm -rf /var/lib/containerd

• Docker 安装

yum -y install gcc
yum -y install gcc-c++
yum install -y yum-utils
yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
yum makecache fast
yum -y install docker-ce docker-ce-cli containerd.io
systemctl enable docker && systemctl start docker
cat > /etc/docker/daemon.json << EOF
{
"registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
EOF
systemctl restart docker

k8s安装

1. 配置k8s安装镜像

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

2. 安装kubeadm 、kubectl、kubelet

yum remove -y kubelet kubeadm kubectl && yum install -y kubelet-1.16.2 kubectl-1.16.2 kubeadm-1.16.2 --disableexcludes=kubernetes

3. 设置kubelet开机自启动

systemctl enable kubelet

master节点配置

1. 创建一个k8s的工作目录，生成一个kubeadm配置文件

mkdir k8s-install && cd k8s-install
kubeadm config print init-defaults > kubeadm.yaml 

2. 修改配置文件

#修改生成好的配置文件镜像与版本
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: 192.169.240.130
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: k8smaster
  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: registry.aliyuncs.com/google_containers #修改镜像源
kind: ClusterConfiguration
kubernetesVersion: v1.16.2 #修改版本
networking:
  dnsDomain: cluster.local
  podSubnet: 10.244.0.0/16 #pod网络
  serviceSubnet: 10.96.0.0/12
scheduler: {}

3. 下载kubeadm所需要的镜像

kubeadm config images pull --config kubeadm.yaml

使用docker images 可查看下载的镜像信息

4. 使用kubeadm 初始化master节点

kubeadm init --config kubeadm.yaml

提示以下信息则表示初始化成功

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 192.168.240.130:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:1877573f37b7fd0bc9d8e38cf8d68f17f51e64a55606f7b657f3cdba79469f16 

5. 按照提示创建目录

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

查看集群节点状态

kubectl get nodes 

此时只有master节点是NotReady状态

6. 将两台node节点 加入到master节点中去（kubeadm join 是在master节点上初始化配置时生成的）

kubeadm join 192.168.240.130:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:1877573f37b7fd0bc9d8e38cf8d68f17f51e64a55606f7b657f3cdba79469f16 

再次查看master节点信息

7. 安装flannel网络插件

wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

编辑kube-flannel.yml

改成虚拟机的网卡名称

8. 下载flannel镜像

docker pull quay.io/coreos/flannel:v0.11.0-amd64
kubectl create -f kube-flannel.yml

9. 查看集群节点状态

kubectl get pods -A

• master节点的组件

1. api-server: api-server是主节点对外开发api的组件，同时提供restful方式,也可以用kubectl方式。
2. etcd： 数据存储组件，api-server会将收到的指令存储到etcd中。
3. sched ：负责接收指令，然后选举合适的node节点，通知节点进行容器的启停、负载均衡等。
4. cm ：主节点控制中心，controller-manager。

• node节点的组件

5. kubelet : 用于管理节点中的容器启停，挂载等等。
6. kube-proxy ： 用于节点间的网络通信、流量转发等。
7. pod : pod是k8s中的最小调度单位，一个pod中可以包含至少1个容器。多个容器组成了一个pod。