前期准备

安装 docker, kubeadm 等必要命令，过程可以参考文章：机器从零到 K8S 集群 Worker 节点的安装过程

kubeadm init

导出默认配置文件

kubeadm 可以使用参数配置，但如果参数较多，建议使用配置文件。

导出配置文件并命名为 kubeadm.yaml

kubeadm config print init-defaults > kubeadm.yaml

（可选）配置镜像仓库

根据网络环境，本人选择 registry.aliyuncs.com/google_containers
配置文件 kubeadm.yaml 中相关行修改为所选镜像：

...
imageRepository: registry.aliyuncs.com/google_containers
...

（可选）kube-proxy 配置 ipvs 模式

可参考官方文档：

• v1beta2 API reference
• KubeProxyConfiguration

在 kubeadm.yaml 末尾添加：

---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: ipvs
---

完整配置文件参考

完整配置文件参考：

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: hyper-sia
  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:
    imageRepository: ""
    dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.17.3
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
  podSubnet: 10.240.0.0/16
scheduler: {}
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: ipvs
---

执行 kubeadm init

sudo kubeadm init --config kubeadm.yaml

输出结果：

W0317 09:37:19.620034    7827 validation.go:28] Cannot validate kube-proxy config - no validator is available
W0317 09:37:19.620074    7827 validation.go:28] Cannot validate kubelet config - no validator is available
[init] Using Kubernetes version: v1.17.3
[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] Starting the kubelet
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [hyper-sia kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.3.200]
[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 "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [hyper-sia localhost] and IPs [192.168.3.200 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [hyper-sia localhost] and IPs [192.168.3.200 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-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"
W0317 09:37:22.004796    7827 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[control-plane] Creating static Pod manifest for "kube-scheduler"
W0317 09:37:22.005387    7827 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[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 34.001805 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.17" 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 hyper-sia as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node hyper-sia 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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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 192.168.3.200:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:9260f901a1702edbca5de31f8d19e4986a753827e12871a4529cc7ee6bb08c13 

到这里还没有结束，还需要执行以下命令：

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

验证状态：

kubectl get nodes

输出结果：

NAME        STATUS     ROLES    AGE     VERSION
hyper-sia   NotReady   master   2m45s   v1.17.3

配置网络（基于 flannel ）

由于缺少网络插件，目前集群状态为 NotReady

GitHub: https://github.com/coreos/flannel
按照官方提供的命令：

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

如果网络条件受限，可能会出错，需要修改镜像源。
先将文件下载到本地：

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

将所有 amd64 版本（根据系统决定）镜像地址由 quay.io 修改为 quay-mirror.qiniu.com：

quay.io/coreos/flannel:v0.12.0-amd64

修改后：

quay-mirror.qiniu.com/coreos/flannel:v0.12.0-amd64

然后执行kubectl apply -f kube-flannel.yml

最后执行可以看到 node 已经 ready， pod 都起来了：

NAME        STATUS   ROLES    AGE   VERSION
hyper-sia   Ready    master   22m   v1.17.3

NAMESPACE     NAME                                READY   STATUS    RESTARTS   AGE
kube-system   coredns-9d85f5447-4tdc2             1/1     Running   0          21m
kube-system   coredns-9d85f5447-gvtml             1/1     Running   0          21m
kube-system   etcd-hyper-sia                      1/1     Running   0          21m
kube-system   kube-apiserver-hyper-sia            1/1     Running   0          21m
kube-system   kube-controller-manager-hyper-sia   1/1     Running   0          21m
kube-system   kube-flannel-ds-amd64-bjnhn         1/1     Running   0          5m57s
kube-system   kube-proxy-l8r8j                    1/1     Running   0          21m
kube-system   kube-scheduler-hyper-sia            1/1     Running   0          21m

如果准备搭建单节点 K8S 或者需要将 master 节点也用于部署 pod， 可以执行命令：

kubectl taint nodes --all node-role.kubernetes.io/master-

此时，该 K8S 集群就可以部署应用了。

集群部署应用验证

部署一个 3 节点的 nginx 集群：

kubectl run my-nginx --image=nginx --port=80 --expose -r3

获取 nginx Service 的 IP：

kubectl get svc/my-nginx

输出结果：

NAME       TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
my-nginx   ClusterIP   10.102.31.20   <none>        80/TCP    81s

使用 curl 连接：

sia@hyper-sia:~$ curl 10.102.31.20
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

验证通过

（可选）添加 Worker 节点

如果要部署 Worker 节点加入到本集群中，可以参考文章：
机器从零到 K8S 集群 Worker 节点的安装过程