一、事前準備

1、所有節點彼此網路互通，並且k8s-m1 SSH 登入其他節點為 passwdless，由於過程中很多會在某臺節點(k8s-m1)上以 SSH 複製與操作其他節點

2、確認所有防火牆與 SELinux 已關閉。如 CentOS：

systemctl stop firewalld && systemctl disable firewalld

setenforce 0

3、所有節點需要設定/etc/hosts解析到所有叢集主機。

4、所有節點需要設定以下系統引數。

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

$ sysctl -p /etc/sysctl.d/k8s.conf

5、關閉系統 Swap，請在所有節點利用以下指令關閉：

$ swapoff -a && sysctl -w vm.swappiness=0

# 不同檔案會有差異
$ sed '/swap.img/d' -i /etc/fstab

二、安裝docker

1、刪除已安裝的Docker

sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine
 

2、配置yum源

cd /etc/yum.repo.d/

yum clean

yum makecache

3、檢視Docker版本：

yum list docker-ce --showduplicates

4、安裝指定版本

yum install -y --setopt=obsoletes=0 \

docker-ce-17.03.2.ce-1.el7.centos.x86_64 \

docker-ce-selinux-17.03.2.ce-1.el7.centos.noarch

啟動docker

systemctl start docker

三、安裝k8s

使用kubeadm安裝：

1.首先配置各節點阿里K8S YUM源

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=0

EOF

yum -y install epel-release

yum clean all

yum makecache

2.在各節點安裝kubeadm和相關工具包（本文安裝的是1.10.0版本）

yum install -y kubelet-1.10.0 kubeadm-1.10.0 kubectl-1.10.0 --disableexcludes=kubernetes

3.啟動kubelet服務

systemctl enable kubelet && systemctl start kubelet

提示：此時kubelet的服務執行狀態是異常的，因為缺少主配置檔案kubelet.conf。但可以暫不處理，因為在完成Master節點的初始化後才會生成這個配置檔案。

修改kubelet配置，啟動kubelet(所有節點)

注意：時刻檢視/var/log/message的日誌輸出，會看到kubelet一直啟動失敗。

4、編輯10-kubeadm.conf的檔案，修改cgroup-driver配置：

1. [[email protected]]# cat /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

2. [Service]

3. Environment="KUBELET_KUBECONFIG_ARGS=--kubeconfig=/etc/kubernetes/kubelet.conf --require-kubeconfig=true"

4. Environment="KUBELET_SYSTEM_PODS_ARGS=--pod-manifest-path=/etc/kubernetes/manifests --allow-privileged=true"

5. Environment="KUBELET_NETWORK_ARGS=--network-plugin=cni --cni-conf-dir=/etc/cni/net.d --cni-bin-dir=/opt/cni/bin"

6. Environment="KUBELET_DNS_ARGS=--cluster-dns=10.96.0.10 --cluster-domain=cluster.local"

7. Environment="KUBELET_AUTHZ_ARGS=--authorization-mode=Webhook --client-ca-file=/etc/kubernetes/pki/ca.crt"

8. Environment="KUBELET_CADVISOR_ARGS=--cadvisor-port=0"

9. Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs"

10. ExecStart=

11. ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_SYSTEM_PODS_ARGS $KUBELET_NETWORK_ARGS $KUBELET_DNS_ARGS $KUBELET_AUTHZ_ARGS $KUBELET_CADVISOR_ARGS $KUBELET_CGROUP_ARGS $KUBELET_EXTRA_ARGS

將“--cgroup-driver=systems”修改成為“--cgroup-driver=cgroupfs”，重新啟動kubelet。

systemctl restart kubelet

4.下載K8S相關映象（Master節點操作）

因為無法直接訪問gcr.io下載映象，所以需要配置一個國內的容器映象加速器

配置一個阿里雲的加速器：

在頁面中找到並點選映象加速按鈕，即可看到屬於自己的專屬加速連結，選擇Centos版本後即可看到配置方法。

提示：在阿里雲上使用 Docker 並配置阿里雲映象加速器，可能會遇到 daemon.json 導致 docker daemon 無法啟動的問題，可以通過以下方法解決。

你需要的是編輯 

vim /etc/sysconfig/docker 

然後 

OPTIONS='--selinux-enabled --log-driver=journald --registry-mirror=http://xxxx.mirror.aliyuncs.com' 
registry-mirror 輸入你的映象地址 

最後 service docker restart 重啟 daemon 

然後 ps aux | grep docker 然後你就會發現帶有映象的啟動引數了。

5.下載K8S相關映象

#!/bin/bash
images=(kube-proxy-amd64:v1.10.0 kube-scheduler-amd64:v1.10.0 kube-controller-manager-amd64:v1.10.0 kube-apiserver-amd64:v1.10.0
etcd-amd64:3.1.12 pause-amd64:3.1 kubernetes-dashboard-amd64:v1.8.3 k8s-dns-sidecar-amd64:1.14.8 k8s-dns-kube-dns-amd64:1.14.8
k8s-dns-dnsmasq-nanny-amd64:1.14.8)
for imageName in ${images[@]} ; do
  docker pull keveon/$imageName
  docker tag keveon/$imageName k8s.gcr.io/$imageName
  docker rmi keveon/$imageName
done

上面的shell指令碼主要做了3件事，下載各種需要用到的容器映象、重新打標記為符合k8s命令規範的版本名稱、清除舊的容器映象。

提示：映象版本一定要和kubeadm安裝的版本一致，否則會出現time out問題。

6.初始化安裝K8S Master

執行上述shell指令碼，等待下載完成後，執行kubeadm init

[[email protected] ~]# kubeadm init --kubernetes-version=v1.10.0 --pod-network-cidr=10.244.0.0/16
[init] Using Kubernetes version: v1.10.0
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
	[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
	[WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[preflight] Starting the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [k8smaster kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.100.202]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [localhost] and IPs [127.0.0.1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [k8smaster] and IPs [10.0.100.202]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] Wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] Wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] Wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] Waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests".
[init] This might take a minute or longer if the control plane images have to be pulled.
[apiclient] All control plane components are healthy after 21.001790 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node k8smaster as master by adding a label and a taint
[markmaster] Master k8smaster tainted and labelled with key/value: node-role.kubernetes.io/master=""
[bootstraptoken] Using token: thczis.64adx0imeuhu23xv
[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: 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 10.0.100.202:6443 --token thczis.64adx0imeuhu23xv --discovery-token-ca-cert-hash sha256:fa7b11bb569493fd44554aab0afe55a4c051cccc492dbdfafae6efeb6ffa80e6

提示：選項--kubernetes-version=v1.10.0是必須的，否則會因為訪問google網站被牆而無法執行命令。這裡使用v1.10.0版本，剛才前面也說到了下載的容器映象版本必須與K8S版本一致否則會出現time out。

上面的命令大約需要1分鐘的過程，期間可以觀察下tail -f /var/log/message日誌檔案的輸出，掌握該配置過程和進度。上面最後一段的輸出資訊儲存一份，後續新增工作節點還要用到。

7.配置kubectl認證資訊（Master節點操作）

# 對於非root使用者
mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config

# 對於root使用者
export KUBECONFIG=/etc/kubernetes/admin.conf

也可以直接放到~/.bash_profile

echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> ~/.bash_profile

8.安裝flannel網路（Master節點操作）

mkdir -p /etc/cni/net.d/

cat <<EOF> /etc/cni/net.d/10-flannel.conf
{
“name”: “cbr0”,
“type”: “flannel”,
“delegate”: {
“isDefaultGateway”: true
}
}

EOF

mkdir /usr/share/oci-umount/oci-umount.d -p

mkdir /run/flannel/

cat <<EOF> /run/flannel/subnet.env
FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.1.0/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

EOF

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.9.1/Documentation/kube-flannel.yml

9.讓node1、node2加入叢集

在node1和node2節點上分別執行kubeadm join命令，加入叢集：

[[email protected] ~]# kubeadm join 10.0.100.202:6443 --token thczis.64adx0imeuhu23xv --discovery-token-ca-cert-hash sha256:fa7b11bb569493fd44554aab0afe55a4c051cccc492dbdfafae6efeb6ffa80e6
[preflight] Running pre-flight checks.
	[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
	[WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[discovery] Trying to connect to API Server "10.0.100.202:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://10.0.100.202:6443"
[discovery] Requesting info from "https://10.0.100.202:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "10.0.100.202:6443"
[discovery] Successfully established connection with API Server "10.0.100.202:6443"

This node has joined the cluster:
* Certificate signing request was sent to master and a response
  was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the master to see this node join the cluster.

提示：細心的童鞋應該會發現，這段命令其實就是前面K8S Matser安裝成功後我讓你們儲存的那段命令。

預設情況下，Master節點不參與工作負載，但如果希望安裝出一個All-In-One的k8s環境，則可以執行以下命令，讓Master節點也成為一個Node節點：

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

10.驗證K8S Master是否搭建成功（Master節點操作）

# 檢視節點狀態
kubectl get nodes

# 檢視pods狀態
kubectl get pods --all-namespaces

# 檢視K8S叢集狀態
kubectl get cs

常見錯誤解析

安裝時候最常見的就是time out，因為K8S映象在國外，所以我們在前面就說到了提前把他下載下來，可以用一個國外機器採用habor搭建一個私有倉庫把映象都download下來。

[[email protected] ~]# kubeadm init
[init] Using Kubernetes version: v1.10.0
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
	[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
	[WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[preflight] Starting the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [k8smaster kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.100.202]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [localhost] and IPs [127.0.0.1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [k8smaster] and IPs [10.0.100.202]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] Wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] Wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] Wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] Waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests".
[init] This might take a minute or longer if the control plane images have to be pulled.

Unfortunately, an error has occurred:
	timed out waiting for the condition

This error is likely caused by:
	- The kubelet is not running
	- The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)
	- Either there is no internet connection, or imagePullPolicy is set to "Never",
	  so the kubelet cannot pull or find the following control plane images:
		- k8s.gcr.io/kube-apiserver-amd64:v1.10.0
		- k8s.gcr.io/kube-controller-manager-amd64:v1.10.0
		- k8s.gcr.io/kube-scheduler-amd64:v1.10.0
		- k8s.gcr.io/etcd-amd64:3.1.12 (only if no external etcd endpoints are configured)

If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
	- 'systemctl status kubelet'
	- 'journalctl -xeu kubelet'
couldn't initialize a Kubernetes cluster

那出現這個問題大部分原因是因為安裝的K8S版本和依賴的K8S相關映象版本不符導致的，關於這部分排錯可以檢視/var/log/message我們在文章開始安裝的時候也提到了要多看日誌。

還有些童鞋可能會說，那我安裝失敗了，怎麼清理環境重新安裝啊？下面教大家一條命令：

kubeadm reset

好了，至此就完成了K8S三節點叢集的安裝部署。

參考文件：