使用kubeadm创建kubernets集群

1. 规划

IP	节点角色	工作职责
172.10.30.100	master	对外暴露API,对内提供工作流的调度和配置
172.10.30.101	node1	承载着k8s运行的实际任务
172.10.30.102	node2	同node1相同

2. 部署前提

主机名称解析，（在/etc/hosts文件编辑相关信息即可）

172.10.30.100 master

172.10.30.101 node1

172.10.30.102 node2

将上述配置文件拷贝到集群中的所有节点，包括master节点和node节点。

时间同步(使用chrony服务实现)

yum -y install chrony 

vim /etc/chrony.conf

~~~
server master
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
~~~~
#注释掉原有的server内容,把原有的时钟同步服务设置为master结点上的时钟同步。

关闭所有节点的iptables和firewalld以及selinux

iptables -F
systemctl stop firewalld
systemctl disable firewalld

sed -i '/^SELINUX=/s/SELINUX=.*/SELINUX=disabled/g' /etc/selinux/config
setenforce 0

禁止iptables对bridge数据进行处理

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

EOF
sysctl -p /etc/sysctl.conf # 不起作用

sysctl -p  /etc/sysctl.d/k8s.conf #这样可以

关闭swap

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

3. docker 安装

参考： https://docs.docker.com/install/linux/docker-ce/centos/#uninstall-old-versions

这里安装特定的版本 docker-ce-18.06。

需要注意的是，Kubernetes 1.13已经针对Docker的1.11.1, 1.12.1, 1.13.1, 17.03, 17.06, 17.09, 18.06等版本做了验证，最低支持的Docker版本是1.11.1，最高支持是18.06，而Docker最新版本已经是18.09了，故我们安装时需要指定版本为18.06.1-ce：

#移除旧版docker
yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine





#依赖

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


#docke-ce 官方yum 源
yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

#阿里的docke-ce yum源 二者用其一
wget -P /etc/yum.repos.d/ https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo #从阿里云获取docker-ce的镜像文件，-P指定下载文件存放的目录

#查看docker版本
yum list docker-ce --showduplicates | sort -r

#安装
yum install docker-ce-18.06.1.ce-3.el7 -y

systemctl start docker

systemctl enable docker

4. kubectl、kubelete、kubeadm安装

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
setenforce 0

yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet

5. 使用kubeadm创建一个单Master集群

5.1初始化Master节点

K8s的控制面板组件运行在Master节点上，包括etcd和API server（Kubectl便是通过API server与k8s通信）。

在执行初始化之前，我们还有一下3点需要注意：

1.选择一个网络插件，并检查它是否需要在初始化Master时指定一些参数，比如我们可能需要根据选择的插件来设置--pod-network-cidr参数。参考：Installing a pod network add-on。

2.kubeadm使用eth0的默认网络接口（通常是内网IP）做为Master节点的advertise address，如果我们想使用不同的网络接口，可以使用--apiserver-advertise-address=<ip-address>参数来设置。如果适应IPv6，则必须使用IPv6d的地址，如：--apiserver-advertise-address=fd00::101。

3.使用kubeadm config images pull来预先拉取初始化需要用到的镜像，用来检查是否能连接到Kubenetes的Registries。

Kubenetes默认Registries地址是k8s.gcr.io，很明显，在国内并不能访问gcr.io，因此在kubeadm v1.13之前的版本，安装起来非常麻烦，但是在1.13版本中终于解决了国内的痛点，其增加了一个--image-repository参数，默认值是k8s.gcr.io，我们将其指定为国内镜像地址：registry.aliyuncs.com/google_containers，其它的就可以完全按照官方文档来愉快的玩耍了。

其次，我们还需要指定--kubernetes-version参数，因为它的默认值是stable-1，会导致从https://dl.k8s.io/release/stable-1.txt下载最新的版本号，我们可以将其指定为固定版本（最新版：v1.13.0）来跳过网络请求。

现在，我们就来试一下：

# 使用calico网络 --pod-network-cidr=192.168.0.0/16
sudo kubeadm init --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.13.0 --pod-network-cidr=192.168.0.0/16

输出

[init] Using Kubernetes version: v1.13.0
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [master localhost] and IPs [172.10.30.100 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [172.10.30.100 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 172.10.30.100]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 26.004391 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.13" in namespace kube-system with the configuration for the kubelets in the cluster
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "master" as an annotation
[mark-control-plane] Marking the node master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 485yy9.azkhnftmz2mf9me5
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[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 172.10.30.100:6443 --token 485yy9.azkhnftmz2mf9me5 --discovery-token-ca-cert-hash sha256:165d19adeaac9bd84837367b414a45b01879dbb8f36092a32b957223904e9c30

输出