centos7使用kubeadm初始化k8s集群（主节点）

1、安装docker，参考 https://docs.docker.com/install/linux/docker-ee/centos/

配置：编辑或创建 /etc/docker/daemon.json

添加 "registry-mirrors": ["https://dockerhub.azk8s.cn","https://reg-mirror.qiniu.com"]

systemctl start docker #启动

systemctl enable docker #开机自启

2、防火墙关闭

systemctl status firewalld.service

systemctl stop firewalld.service #停止firewall

systemctl disable firewalld.service #禁止firewall开机启动

3、swap 关闭

swapoff -a 临时关闭

用vi修改/etc/fstab文件，在swap分区这行前加 # 禁用掉，保存退出

4、配置k8s使用repo，使用阿里云镜像仓库

    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

SELinux是一种基于 域-类型 模型（domain-type）的强制访问控制（MAC）安全系统，需修改器配置

    setenforce 0  关闭selinux

    sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

5、配置k8s操作网络许可配置

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

如果是测试机器的，这里可以重启一下机器

6、安装组件（注版本需要配套使用，高版本可能拉取不到相关容器镜像）

    yum clean all
    yum makecache
    yum install kubernetes-cni-0.6.0 kubelet-1.13.4 kubeadm-1.13.4 kubectl-1.13.4

7、查看所需的镜像

    kubeadm config images list

        k8s.gcr.io/kube-apiserver:v1.13.4
    k8s.gcr.io/kube-controller-manager:v1.13.4
    k8s.gcr.io/kube-scheduler:v1.13.4
    k8s.gcr.io/kube-proxy:v1.13.4
    k8s.gcr.io/pause:3.1
    k8s.gcr.io/etcd:3.2.24
    k8s.gcr.io/coredns:1.2.6

除了这些还有一个 quay.io/coreos/flannel:v0.11.0-amd64，kubernetes-cni网络插件所需要的一个容器镜像

文档：https://github.com/coreos/flannel/tree/master/Documentation

不然会报错误 Unable to update cni config: No networks found in /etc/cni/net.d

Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized

8、拉取相关容器镜像，

        docker pull mirrorgooglecontainers/kube-apiserver:v1.13.4
    docker pull mirrorgooglecontainers/kube-controller-manager:v1.13.4
    docker pull mirrorgooglecontainers/kube-scheduler:v1.13.4
    docker pull mirrorgooglecontainers/kube-proxy:v1.13.4
    docker pull mirrorgooglecontainers/pause:3.1
    docker pull mirrorgooglecontainers/etcd:3.2.24
    docker pull coredns/coredns:1.2.6
    docker pull jmgao1983/flannel:v0.11.0-amd64


    docker tag mirrorgooglecontainers/kube-apiserver:v1.13.4 k8s.gcr.io/kube-apiserver:v1.13.4 

    docker tag mirrorgooglecontainers/kube-controller-manager:v1.13.4 k8s.gcr.io/kube-controller-manager:v1.13.4

    docker tag mirrorgooglecontainers/kube-scheduler:v1.13.4 k8s.gcr.io/kube-scheduler:v1.13.4

    docker tag mirrorgooglecontainers/kube-proxy:v1.13.4 k8s.gcr.io/kube-proxy:v1.13.4

    docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1

    docker tag mirrorgooglecontainers/etcd:3.2.24 k8s.gcr.io/etcd:3.2.24

    docker tag coredns/coredns:1.2.6 k8s.gcr.io/coredns:1.2.6

    docker tag jmgao1983/flannel:v0.11.0-amd64 quay.io/coreos/flannel:v0.11.0-amd64

9、kubeadm初始化

kubeadm init kubernetes-version=v1.13.4 --pod-network-cidr=10.244.0.0/16

   # kubectl get pods --all-namespaces

NAMESPACE     NAME                                 READY   STATUS    RESTARTS   AGE

kube-system   coredns-86c58d9df4-p7clm             1/1     Running   0          3h39m

kube-system   coredns-86c58d9df4-qdwvk             1/1     Running   0          3h39m

kube-system   etcd-master.k8s                      1/1     Running   0          3h39m

kube-system   kube-apiserver-master.k8s            1/1     Running   0          3h39m

kube-system   kube-controller-manager-master.k8s   1/1     Running   0          3h39m

kube-system   kube-flannel-ds-amd64-rtrrq          1/1     Running   0          152m

kube-system   kube-proxy-dcxz2                     1/1     Running   0          3h39m

kube-system   kube-scheduler-master.k8s            1/1     Running   0          3h39m

10、