环境
三台 CentOS 7.4 服务器：kube1 、kube2 、kube3 ，配置：2 核 16G
关闭、禁用防火墙：
systemctl stop firewalld
systemctl disable firewalld
禁用SELINUX：
setenforce 0
创建 /etc/sysctl.d/k8s.conf 文件，添加如下内容：
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
执行如下命令使修改生效：
modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf
安装 Docker
# step 1: 安装必要的一些系统工具
sudo yum install -y yum-utils device-mapper-persistent-data lvm2
# Step 2: 添加软件源信息
sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
# Step 3: 更新并安装 Docker-CE
sudo yum makecache fast
sudo yum -y install docker-ce
# Step 4: 开启Docker服务
sudo service docker start
# Step 5: 设置开机启动
sudo systemctl enable docker
配置阿里云镜像加速器：
mkdir -p /etc/docker
tee /etc/docker/daemon.json <<-'EOF'
{
"registry-mirrors": ["https://obww7jh1.mirror.aliyuncs.com"]
}
EOF
systemctl daemon-reload
systemctl restart docker
安装 kubelet kubeadm kubectl
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
yum install -y kubelet kubeadm kubectl
systemctl enable --now kubelet
构建 Kubernetes 集群
1、初始化 Master 节点 kube1
kubeadm init --pod-network-cidr=10.244.0.0/16 --image-repository=registry.aliyuncs.com/google_containers
- --pod-network-cidr ：后续安装
flannel的前提条件，且值为10.244.0.0/16， 参考资料 - --image-repository ：指定镜像仓库
输出日志：
.....
[addons] Applied essential addon: kube-dns
[addons] Applied essential addon: kube-proxy
Your Kubernetes master 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 machines by running the following on each node
as root:
kubeadm join 172.17.58.201:6443 --token 831rfg.dw0vyb1h3beab5as --discovery-token-ca-cert-hash sha256:623681fde5b2bf564a8631942f31797f9bef75f40b14a86ef75e1d31b43709f1
从日志中，可以看出，要使用集群，需要执行如下命令：
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
还需要部署一个 Pod Network 到集群中，此处选择 flannel ：
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml
至此，Master 节点初始化完毕，查看集群相关信息：
# 查看集群信息
$ kubectl cluster-info
Kubernetes master is running at https://172.17.58.201:6443
KubeDNS is running at https://172.17.58.201:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
# 查看节点信息
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
lab-backend1 Ready master 1m v1.15.0
# 查看 Pods 信息
$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-bccdc95cf-qp4wl 1/1 Running 0 14m
kube-system coredns-bccdc95cf-z9nwp 1/1 Running 0 14m
kube-system etcd-k8s-1 1/1 Running 0 13m
kube-system kube-apiserver-k8s-1 1/1 Running 0 14m
kube-system kube-controller-manager-k8s-1 1/1 Running 0 13m
kube-system kube-scheduler-k8s-1 1/1 Running 0 13m
如果初始化过程出现问题，使用如下命令重置：
kubeadm reset
rm -rf /var/lib/cni/
rm -f $HOME/.kube/config
2、添加 Worker 节点
方式 ① 使用 kubeadm init 时返回的信息加入集群 kube2 / kube3
kubeadm join 172.17.58.201:6443 --token 831rfg.dw0vyb1h3beab5as --discovery-token-ca-cert-hash sha256:623681fde5b2bf564a8631942f31797f9bef75f40b14a86ef75e1d31b43709f1
方式 ② 重新生成 token kube1
kubeadm token generate
kubeadm token create <generated-token> --print-join-command --ttl=24h
- --ttl=24h 代表这个Token 的有效期为 24 小时，初始化默认生成的 token 有效期也为 24 小时
加入集群 kube2 / kube3
kubeadm join 172.17.58.201:6443 --token 41ts3r.n2vw06xbniouo6u5 --discovery-token-ca-cert-hash sha256:f958e234e8554c2352127f356a7eb7dad422c10df9a749156df36e5972cba38b
再次查看集群节点 kube1
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
lab-backend1 Ready master 6m v1.15.0
lab-backend2 Ready <none> 56s v1.15.0
lab-backend3 Ready <none> 14s v1.15.0
至此，1 Master + 2 Worker 的 kubernetes 集群就创建成功了。
