kubeadm搭建单master集群

版本：kubernetes v1.17.2
环境准备
3个节点，都是 Centos 7.6 系统，内核版本：3.10.0-957.12.2.el7.x86_64，在每个节点上添加 hosts 信息：
$ cat /etc/hosts

172.16.1.128 k8s-master
172.16.1.129 k8s-node01
172.16.1.130 k8s-node02

禁用防火墙：

$ systemctl stop firewalld
$ systemctl disable firewalld

禁用SELINUX：

$ setenforce 0
$ cat /etc/selinux/config
SELINUX=disabled

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 ipvs

$ cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
$ chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

上面脚本创建了的/etc/sysconfig/modules/ipvs.modules文件，保证在节点重启后能自动加载所需模块。使用lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已经正确加载所需的内核模块。
接下来还需要确保各个节点上已经安装了 ipset 软件包：

$ yum install ipset -y

为了便于查看 ipvs 的代理规则，最好安装一下管理工具 ipvsadm：

$ yum install ipvsadm -y

同步服务器时间

$ yum install chrony -y
$ systemctl enable chronyd
$ systemctl start chronyd
$ chronyc sources

关闭 swap 分区：

$ swapoff -a

修改/etc/fstab文件，注释掉 SWAP 的自动挂载，使用free -m确认 swap 已经关闭。swappiness 参数调整，修改/etc/sysctl.d/k8s.conf添加下面一行：

vm.swappiness=0

执行sysctl -p /etc/sysctl.d/k8s.conf使修改生效。
接下来可以安装 Docker

$ yum install -y yum-utils \
 device-mapper-persistent-data \
 lvm2
$ yum-config-manager \
 --add-repo \
 https://download.docker.com/linux/centos/docker-ce.repo
$ yum list docker-ce --showduplicates | sort -r

可以选择安装一个版本，比如我们这里安装最新版本：

$ yum install docker-ce-18.09.8-3.el7 -y

配置 Docker 镜像加速器
$ vi /etc/docker/daemon.json

{
 "exec-opts": ["native.cgroupdriver=systemd"],
 "registry-mirrors" : [
 "https://ot2k4d59.mirror.aliyuncs.com/"
 ]
}

启动 Docker

$ systemctl start docker
$ systemctl enable docker

在确保 Docker 安装完成后，上面的相关环境配置也完成了，现在我们就可以来安装 Kubeadm 了，我们这里是通过指定yum 源的方式来进行安装的：

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

当然了，上面的 yum 源是需要梯子的，如果没有梯子的话，我们可以使用阿里云的源进行安装：

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

然后安装 kubeadm、kubelet、kubectl（我安装的是最新版，有版本要求自己设定版本）：

$ yum install -y kubelet-1.17.2 kubeadm-1.17.2 kubectl-1.17.2 --disableexcludes=kubernetes

可以看到我们这里安装的是 v1.17.2 版本，然后将 kubelet 设置成开机启动：

$ systemctl enable kubelet.service

到这里为止上面所有的操作都需要在所有节点执行配置。

初始化集群
然后接下来在 master 节点配置 kubeadm 初始化文件，可以通过如下命令导出默认的初始化配置：

$ kubeadm config print init-defaults > kubeadm.yaml

然后根据我们自己的需求修改配置，比如修改 imageRepository 的值，kube-proxy 的模式为 ipvs，另外需要注意的是我们这里是准备安装 calico 网络插件的，需要将 networking.podSubnet 设置为192.168.0.0/16：

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: 172.16.1.128
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: k8s-master
  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.cn-hangzhou.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.17.2
networking:
  dnsDomain: cluster.local
  podSubnet: 192.168.0.0/16
  serviceSubnet: 10.96.0.0/12
scheduler: {}
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: ipvs

然后使用上面的配置文件进行初始化：

$ kubeadm init --config kubeadm.yaml

[init] Using Kubernetes version: v1.17.2
[preflight] Running pre-flight checks
 [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.1. Latest validated version: 18.09
[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 "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [ydzs-master localhost] and IPs [10.151.30.11 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [ydzs-master localhost] and IPs [10.151.30.11 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/healthcheck-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 [ydzs-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.151.30.11]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-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
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 42.012149 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node ydzs-master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node ydzs-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
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 172.16.1.128:6443 --token abcdef.0123456789abcdef \
 --discovery-token-ca-cert-hash sha256:deb5158b39948a4592ff48512047ea6e45b288c248872724a28f15008962178b

可以看到最新验证的 docker 版本是18.09，虽然是一个 warning，所以最好还是安装18.09版本的 docker。

拷贝 kubeconfig 文件

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

添加节点
记住初始化集群上面的配置和操作要提前做好，将 master 节点上面的 $HOME/.kube/config 文件拷贝到 node 节点对应的文件中，安装 kubeadm、kubelet、kubectl，然后执行上面初始化完成后提示的 join 命令即可：

kubeadm join 172.16.1.128:6443 --token abcdef.0123456789abcdef \
 --discovery-token-ca-cert-hash sha256:deb5158b39948a4592ff48512047ea6e45b288c248872724a28f15008962178b
        
        [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-1.15" 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.

如果忘记了上面的 join 命令可以使用命令kubeadm token create --print-join-command重新获取。

执行成功后运行 get nodes 命令：

# kubectl get nodes 
NAME         STATUS   ROLES    AGE     VERSION
k8s-master   Ready    master   3d18h   v1.17.2
k8s-node01   Ready    node01   3d18h   v1.17.2
k8s-node02   Ready    node02   3d17h   v1.17.2

可以看到是 NotReady 状态，这是因为还没有安装网络插件，接下来安装网络插件，可以在文档 https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/ 中选择我们自己的网络插件，这里我们安装 calio:

$ wget https://docs.projectcalico.org/v3.8/manifests/calico.yaml

因为有节点是多网卡，所以需要在资源清单文件中指定内网网卡
$ vi calico.yaml

......
spec:
 containers:
 - env:
 - name: DATASTORE_TYPE
 value: kubernetes
 - name: IP_AUTODETECTION_METHOD # DaemonSet中添加该环境变量
 value: interface=ens33 # 指定内网网卡
 - name: WAIT_FOR_DATASTORE
 value: "true"
......

$ kubectl apply -f calico.yaml # 安装calico网络插件


隔一会儿查看 Pod 运行状态：

# kubectl get pod -n kube-system 
NAME                                       READY   STATUS    RESTARTS   AGE
calico-kube-controllers-64d7686ff8-q4wwg   1/1     Running   0          10m
calico-node-92b29                          1/1     Running   0          3d17h
calico-node-f8shx                          1/1     Running   7          3d17h
calico-node-jsk9r                          1/1     Running   0          3d17h
coredns-6cd559f5d5-448x5                   1/1     Running   0          3d18h
coredns-6cd559f5d5-tprrj                   1/1     Running   0          3d18h
etcd-k8s-master                            1/1     Running   1          3d18h
kube-apiserver-k8s-master                  1/1     Running   4          3d18h
kube-controller-manager-k8s-master         1/1     Running   18         3d18h
kube-proxy-7hk2n                           1/1     Running   1          3d18h
kube-proxy-ffslj                           1/1     Running   1          3d17h
kube-proxy-txhcq                           1/1     Running   1          3d18h
kube-scheduler-k8s-master                  1/1     Running   17         3d18h

网络插件运行成功了，node 状态也正常了：

# kubectl get nodes 
NAME         STATUS   ROLES    AGE     VERSION
k8s-master   Ready    master   3d18h   v1.17.2
k8s-node01   Ready    node01   3d18h   v1.17.2
k8s-node02   Ready    node02   3d17h   v1.17.2

用同样的方法添加另外一个节点即可。


安装 Dashboard

$ wget https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml
$ vi kubernetes-dashboard.yaml

修改镜像名称

......
containers:
- args:
 - --auto-generate-certificates
 image: gcr.azk8s.cn/google_containers/kubernetes-dashboard-amd64:v1.10.1
 imagePullPolicy: IfNotPresent
......

修改Service为NodePort类型

......
selector:
 k8s-app: kubernetes-dashboard
type: NodePort
......

直接创建：

$ kubectl apply -f kubernetes-dashboard.yaml
$ kubectl get pods -n kube-system -l k8s-app=kubernetes-dashboard
NAME READY STATUS RESTARTS AGE
kubernetes-dashboard-fcfb4cbc-t462n 1/1 Running 0 50m
$ kubectl get svc -n kube-system -l k8s-app=kubernetes-dashboard
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes-dashboard NodePort 10.110.172.49 <none> 443:32497/TCP 55m

然后可以通过上面的 32497 端口去访问 Dashboard，要记住使用 https，Chrome不生效可以使用Firefox测试：

k8s dashboard login
然后创建一个具有全局所有权限的用户来登录Dashboard：(admin.yaml)

kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
 name: admin
 annotations:
 rbac.authorization.kubernetes.io/autoupdate: "true"
roleRef:
 kind: ClusterRole
 name: cluster-admin
 apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
 name: admin
 namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
 name: admin
 namespace: kube-system
 labels:
 kubernetes.io/cluster-service: "true"
 addonmanager.kubernetes.io/mode: Reconcile

直接创建：

$ kubectl apply -f admin.yaml
$ kubectl get secret -n kube-system|grep admin-token
admin-token-d5jsg kubernetes.io/service-account-token 3 1d
$ kubectl get secret admin-token-d5jsg -o jsonpath={.data.token} -n kube-system |base64 -d# 会生成一串很长的base64后的字符串

然后用上面的base64解码后的字符串作为token登录Dashboard即可：
最终我们就完成了使用 kubeadm 搭建 v1.17.2 版本的 kubernetes 集群、coredns、ipvs、calico。


配置命令自动补全

yum install -y bash-completion
source /usr/share/bash-completion/bash_completion
source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc