K8S
kubernetes（K8S）是什麼
Kubernetes（常簡稱為K8S）是用於自動部署、擴展和管理容器化（containerized）應用程序的開源系統。系統由Google設計並捐贈給Cloud Native Computing Foundation（今屬Linux基金會）來使用。
它旨在提供“跨主機集群的自動部署、擴展以及運行應用程序容器的平臺”。它支持一系列容器工具, 包括Docker等。我們可以將Docker看成Kubernetes內部使用的低級別組件。
為什麼要使用kubernetes
Docker這個新興的容器化技術當前應用越來越廣，並且其從單機走向集群也稱為必然，而云計算的蓬勃發展正在加速這一進程。kubernetes作為當前普遍被業界廣泛認可和看好的docker分佈式系統解決方案，前景非常可觀。
使用Kubernetes可以做什麼：
- 自動化容器的部署和複製
- 隨時擴展或收縮容器規模
- 將容器組織成組，並且提供容器間的負載均衡
- 很容易地升級應用程序容器的新版本
- 提供容器彈性，如果容器失效就替換它
部署環境準備
機器信息
機器信息
關閉防火牆及selinux
# systemctl stop firewalld
# systemctl disable firewalld
# setenforce 0
修改hosts
172.17.0.218 k8sm-218
172.17.0.219 k8s-219
172.17.0.220 k8s-220
增加網絡轉發
# cat </etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
# sysctl --system //使配置生效
安裝組件
安裝指定版本Docker
# wget -O /etc/yum.repos.d/docker-ce.repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
# yum install docker-ce-18.06.1.ce-3.el7 -y
# systemctl start docker
# systemctl enable docker
安裝指定版本kubelet，kubeadm，kubectl
# cat </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
# yum install kubelet-1.13.3 -y
# yum install kubeadm-1.13.3 -y
# yum install kubectl-1.13.3 -y
# systemctl enable kubelet
初始化master
# kubeadm init --kubernetes-version=v1.13.3 --apiserver-advertise-address=172.17.0.218 --image-repository registry.aliyuncs.com/google_containers --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12
參數含義：
--kubernetes-version：指定kubeadm版本；
--pod-network-cidr：指定pod所屬網絡
--image-repository 指定下載源
--service-cidr：指定service網段,負載均衡ip
--ignore-preflight-errors=Swap/all：忽略 swap/所有 報錯
初始化成功結果
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 172.17.0.218:6443 --token ai3bxc.zgq33i1sbdybhnci --discovery-token-ca-cert-hash sha256:20cb9ccc07e2612bc3b31bd7b5e8909bdbd3d293e7c7f4c18dbee6f62ea94788
增加kubectl權限訪問
此處為初始化成功輸出的內容，複製即可
# mkdir -p $HOME/.kube
# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
# sudo chown $(id -u):$(id -g) $HOME/.kube/config
安裝pod網絡組件
# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
增加node到集群裡
// master初始化後的命令
# kubeadm join 172.17.0.218:6443 --token ai3bxc.zgq33i1sbdybhnci --discovery-token-ca-cert-hash sha256:20cb9ccc07e2612bc3b31bd7b5e8909bdbd3d293e7c7f4c18dbee6f62ea94788
master節點查看node狀態
# kubectl get node
NAME STATUS ROLES AGE VERSION
k8s-219 Ready <none> 112m v1.13.3
k8s-220 Ready <none> 113m v1.13.3
k8sm-218 Ready master 162m v1.13.3/<none>/<none>
部署webui dashboard
下載官方的yaml文件:
# wget https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml
修改兩個地方
第一個是修改鏡像,kubernetes-dashboard.yaml配置文件112行
90 # ------------------- Dashboard Deployment ------------------- #
91
92 kind: Deployment
93 apiVersion: apps/v1
94 metadata:
95 labels:
96 k8s-app: kubernetes-dashboard
97 name: kubernetes-dashboard
98 namespace: kube-system
99 spec:
100 replicas: 1
101 revisionHistoryLimit: 10
102 selector:
103 matchLabels:
104 k8s-app: kubernetes-dashboard
105 template:
106 metadata:
107 labels:
108 k8s-app: kubernetes-dashboard
109 spec:
110 containers:
111 - name: kubernetes-dashboard
112 #image: k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1
113 image: mirrorgooglecontainers/kubernetes-dashboard-amd64:v1.10.0
114 ports:
115 - containerPort: 8443
116 protocol: TCP
第二個是添加一個type,指定端口類型為 NodePort，這樣外界可以通過地址 nodeIP:nodePort 訪問 dashboard,kubernetes-dashboard.yaml配置文件158行:
148 # ------------------- Dashboard Service ------------------- #
149
150 kind: Service
151 apiVersion: v1
152 metadata:
153 labels:
154 k8s-app: kubernetes-dashboard
155 name: kubernetes-dashboard
156 namespace: kube-system
157 spec:
158 type: NodePort
159 ports:
160 - port: 443
161 targetPort: 8443
162 selector:
163 k8s-app: kubernetes-dashboard
部署到k8s集群
# kubectl apply -f kubernetes-dashboard.yaml
# kubectl get pods -n kube-system |grep dashboard
kubernetes-dashboard-6685cb584f-xlk2h 1/1 Running 0 98s
# kubectl get pods,svc -n kube-system
NAME READY STATUS RESTARTS AGE
pod/coredns-78d4cf999f-5hcjm 1/1 Running 0 3h21m
pod/coredns-78d4cf999f-6mlql 1/1 Running 0 3h21m
pod/etcd-k8sm-218 1/1 Running 0 3h20m
pod/kube-apiserver-k8sm-218 1/1 Running 0 3h19m
pod/kube-controller-manager-k8sm-218 1/1 Running 0 3h20m
pod/kube-flannel-ds-amd64-6kfhg 1/1 Running 0 3h13m
pod/kube-flannel-ds-amd64-c4fr4 1/1 Running 0 152m
pod/kube-flannel-ds-amd64-qhc2w 1/1 Running 0 151m
pod/kube-proxy-7hntq 1/1 Running 0 151m
pod/kube-proxy-b4txb 1/1 Running 0 3h21m
pod/kube-proxy-bz529 1/1 Running 0 152m
pod/kube-scheduler-k8sm-218 1/1 Running 0 3h20m
pod/kubernetes-dashboard-6685cb584f-xlk2h 1/1 Running 0 3m5s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP 3h21m
service/kubernetes-dashboard NodePort 10.104.4.26 <none> 443:31667/TCP 3m5s/<none>/<none>
通過https訪問ui
登錄頁
Token （令牌） 認證方式登錄
1）授權 (所有 namespace )
// 創建serviceaccount
# kubectl create serviceaccount dashboard-serviceaccount -n kube-system
// 創建clusterrolebinding
# kubectl create clusterrolebinding dashboard-cluster-admin --clusterrole=cluster-admin --serviceaccount=kube-system:dashboard-serviceaccount
2）獲取令牌（用於網頁登錄）
// 查看口令列表
# kubectl get secret -n kube-system |grep dashboard-serviceaccount-token
dashboard-serviceaccount-token-f45wg kubernetes.io/service-account-token 3 22s
// 獲取口令
# kubectl describe secret dashboard-serviceaccount-token-f45wg -n kube-system
3）將獲取到的token放在令牌裡
輸入token
4）登錄成功
K8S UI
至此，K8S集群+Dashboard搭建成功！
後記
此篇不涉及理論，面向對象是剛接觸K8S的朋友，最小成本來搭建一套K8S集群，以最快時間來看到效果，增加學習的信心^_^
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