0. 概要

使用kubeadm搭建一個單節點kubernets例項,僅供學習. 執行環境和軟體概要如下:

以上系統和軟體基本是2018最新的狀態, 其中docker需要注意必須安裝k8s支援到的版本.

1. 安裝步驟

• 關閉防火牆

swapoff -a

• 安裝執行時, 預設使用docker, 安裝docker即可

apt-get install docker-ce=18.06.1~ce~3-0~ubuntu

• 安裝kubeadm 一下命令和官網的命令一致, 但是是包源改為阿里雲

apt-get update && apt-get install -y apt-transport-https

curl -s https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | apt-key add -

cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
EOF

apt-get update

apt-get install -y kubelet kubeadm kubectl

apt-mark hold kubelet kubeadm kubectl
 

2. 使用kubeadm建立叢集

2.1 準備映象

因為國內是訪問不到k8s.gcr.io所以需要將需要的映象提前下載, 這次採用從阿里雲映象倉庫下載, 並修改下載後的映象tag為k8s.gcr.io

# a. 檢視都需要哪些映象需要下載
kubeadm config images list --kubernetes-version=v1.12.3

k8s.gcr.io/kube-apiserver:v1.12.3
k8s.gcr.io/kube-controller-manager:v1.12.3
k8s.gcr.io/kube-scheduler:v1.12.3
k8s.gcr.io/kube-proxy:v1.12.3
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.2.24
k8s.gcr.io/coredns:1.2

# b. 建立一個自動處理指令碼下載映象->重新tag->刪除老tag
vim ./load_images.sh

#!/bin/bash
### config the image map
declare -A images map=()
images["k8s.gcr.io/kube-apiserver:v1.12.3"]="registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.12.3"
images["k8s.gcr.io/kube-controller-manager:v1.12.3"]="registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.12.3"
images["k8s.gcr.io/kube-scheduler:v1.12.3"]="registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.12.3"
images["k8s.gcr.io/kube-proxy:v1.12.3"]="registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.12.3"
images["k8s.gcr.io/pause:3.1"]="registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.1"
images["k8s.gcr.io/etcd:3.2.24"]="registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.2.24"
images["k8s.gcr.io/coredns:1.2.2"]="registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.2.2"
### re-tag foreach
for key in ${!images[@]}
do
	docker pull ${images[$key]}
	docker tag ${images[$key]} $key
	docker rmi ${images[$key]}
done
### check
docker images

# c. 執行指令碼準映象
sudo chmod +x load_images.sh
./load_images.sh
 

2.2 初始化叢集(master)

初始化需要指定至少兩個引數:

• kubernetes-version: 方式kubeadm訪問外網獲取版本
• pod-network-cidr: flannel網路外掛配置需要

### 執行初始化命令
sudo kubeadm init --kubernetes-version=v1.12.3 --pod-network-cidr=10.244.0.0/16

### 最後的結果如下
... ...
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 192.168.132.152:6443 --token ymny55.4jlbbkxiggmn9ezh --discovery-token-ca-cert-hash sha256:70265fafdb22d524c15616543d0b76527c686329221340b3b8da3652abed46b9

2.3 根據成功資訊配置非管理員賬號使用kubectl

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

使用非root賬號檢視節點情況:

kubectl get nodes

NAME           STATUS     ROLES    AGE   VERSION
servermaster   NotReady   master   28m   v1.12.3

發現有一個master節點, 但是狀態是NotReady, 這裡需要做一個決定:

如果希望是單機則執行如下

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

如果希望搭建繼續, 則繼續後續步驟, 此時主節點狀態可以忽略.

2.4 應用網路外掛

檢視kube-flannel.yml檔案內容, 複製到本地檔案避免terminal無法遠端獲取

kubectl apply -f kube-flannel.yml

clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

2.5 新建worker節點

worker節點新建參考[1. 安裝步驟]在另外一臺伺服器上新建即可, worker節點不用準備2.1~2.3及之後的所有步驟, 僅需完成基本安裝, 安裝完畢進入新的worker節點, 執行上一步最後得到join命令:

kubeadm join 192.168.132.152:6443 --token ymny55.4jlbbkxiggmn9ezh --discovery-token-ca-cert-hash sha256:70265fafdb22d524c15616543d0b76527c686329221340b3b8da3652abed46b9

... ...
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 master to see this node join the cluster.

2.6 檢查叢集(1 master, 1 worker)

kubectl get nodes

NAME           STATUS   ROLES    AGE   VERSION
servermaster   Ready    master   94m   v1.12.3
worker01       Ready    <none>   54m   v1.12.3

2.5 建立dashboard

複製kubernetes-dashboard.yaml內容到本地檔案

kubectl create -f kubernetes-dashboard.yaml 

secret/kubernetes-dashboard-certs created
serviceaccount/kubernetes-dashboard created
role.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
deployment.apps/kubernetes-dashboard created
service/kubernetes-dashboard created

瀏覽器輸入worker節點ip和埠使用https訪問如下:https://my.worker01.local:30000/#!/login 即可以驗證dashboard是否安裝成功.

3. 遇到問題

• master搭建好了, worker也join了get nodes發現還是NotReady狀態

  原因: 太複雜說不清楚任然是一個k8s issue, 檢視issue基本可以確定是cni(Container Network Interface)問題,而flannel覆蓋修改了這個問題

  解決方法: 安裝flannel外掛(kubectl apply -f kube-flannel.yml)

• 配置錯誤重新開始搭建叢集

  解決方案: kubeadm reset

• 不能訪問dashboard

  原因: Back-off pulling image "k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.0

  解決方案:

  1. 修改 kubernetes-dashboard-ce.yaml 檔案中的 k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.0 為 registry.cn-hangzhou.aliyuncs.com/google_containers/kubernetes-dashboard-amd64:v1.10.0

  2. 提前下載好映象並配置好tag, 注意下載的位置worker節點, 可以通過: kubectl describe pod kubernetes-dashboard-85477d54d7-wzt7 -n kube-system 檢視比較具體的資訊

4. 參考資料

安裝kuadmin相關:

• Installing kubeadm
• kubernetes-for-china

建立叢集相關:

• Creating a single master cluster with kubeadm
• 基於Ubuntu16.04和kubeadm部署kuernetes