K8s深入了解

Ingress控制器介紹

1.沒有ingress之前，pod對外提供服務只能通過NodeIP:NodePort的形式，但是這種形式有缺點，一個節點上的PORT不能重復利用。比如某個服務占用了80，那么其他服務就不能在用這個端口了。
2.NodePort是4層代理，不能解析7層的http，不能通過域名區分流量
3.為了解決這個問題，我們需要用到資源控制器叫Ingress，作用就是提供一個統一的訪問入口。工作在7層
4.雖然我們可以使用nginx/haproxy來實現類似的效果，但是傳統部署不能動態的發現我們新創建的資源，必須手動修改配置文件並重啟。
5.適用於k8s的ingress控制器主流的有ingress-nginx和traefik
6.ingress-nginx == nginx + go --> deployment部署 
7.traefik有一個UI界面 

安裝部署traefik

1.traefik_dp.yaml
kind: Deployment
apiVersion: apps/v1
metadata:
  name: traefik-ingress-controller
  namespace: kube-system
  labels:
    k8s-app: traefik-ingress-lb
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: traefik-ingress-lb
  template:
    metadata:
      labels:
        k8s-app: traefik-ingress-lb
        name: traefik-ingress-lb
    spec:
      serviceAccountName: traefik-ingress-controller
      terminationGracePeriodSeconds: 60
      tolerations:
      - operator: "Exists"
      nodeSelector:
        kubernetes.io/hostname: node1 
      containers:
      - image: traefik:v1.7.17
        name: traefik-ingress-lb
        ports:
        - name: http
          containerPort: 80
          hostPort: 80
        - name: admin
          containerPort: 8080
        args:
        - --api
        - --kubernetes
        - --logLevel=INFO

2.traefik_rbac.yaml
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: traefik-ingress-controller
  namespace: kube-system
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: traefik-ingress-controller
rules:
  - apiGroups:
      - ""
    resources:
      - services
      - endpoints
      - secrets
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - extensions
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: traefik-ingress-controller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: traefik-ingress-controller
subjects:
- kind: ServiceAccount
  name: traefik-ingress-controller
  namespace: kube-system

3.traefik_svc.yaml
kind: Service
apiVersion: v1
metadata:
  name: traefik-ingress-service
  namespace: kube-system
spec:
  selector:
    k8s-app: traefik-ingress-lb
  ports:
    - protocol: TCP
      port: 80
      name: web
    - protocol: TCP
      port: 8080
      name: admin
  type: NodePort

4.應用資源配置
kubectl create -f ./

5.查看並訪問
kubectl -n kube-system get svc 

創建traefik的web-ui的ingress規則

1.類比nginx:
upstream traefik-ui {
    server traefik-ingress-service:8080;
}

server {
    location / { 
        proxy_pass http://traefik-ui;
        include proxy_params;
    }
}


2.ingress寫法:
apiVersion: extensions/v1beta1
kind: Ingress
metadata: 
  name: traefik-ui
  namespace: kube-system
spec:
  rules:
    - host: traefik.ui.com 
      http:
        paths:
          - path: /
            backend:
              serviceName: traefik-ingress-service 
              servicePort: 8080

3.訪問測試：
traefik.ui.com

ingress實驗

1.實驗目標
未使用ingress之前只能通過IP+端口訪問：
tomcat 8080
nginx  8090

使用ingress之后直接可以使用域名訪問：
traefik.nginx.com:80   -->  nginx  8090
traefik.tomcat.com:80  -->  tomcat 8080

2.創建2個pod和svc
mysql-dp.yaml  
mysql-svc.yaml 
tomcat-dp.yaml  
tomcat-svc.yaml

nginx-dp.yaml  
nginx-svc-clusterip.yaml  

3.創建ingress控制器資源配置清單並應用
cat >nginx-ingress.yaml <<EOF
apiVersion: extensions/v1beta1
kind: Ingress
metadata: 
  name: traefik-nginx
  namespace: default 
spec:
  rules:
    - host: traefik.nginx.com 
      http:
        paths:
          - path: /
            backend:
              serviceName: nginx-service 
              servicePort: 80
EOF

cat >tomcat-ingress.yaml<<EOF
apiVersion: extensions/v1beta1
kind: Ingress
metadata: 
  name: traefik-tomcat
  namespace: default 
spec:
  rules:
    - host: traefik.tomcat.com 
      http:
        paths:
          - path: /
            backend:
              serviceName: myweb
              servicePort: 8080
EOF

kubectl apply -f nginx-ingress.yaml 
kubectl apply -f tomcat-ingress.yaml 

4.查看創建的資源
kubectl get svc
kubectl get ingresses
kubectl describe ingresses traefik-nginx
kubectl describe ingresses traefik-tomcat

5.訪問測試
traefik.nginx.com
traefik.tomcat.com

數據持久化

Volume介紹

Volume是Pad中能夠被多個容器訪問的共享目錄
Kubernetes中的Volume不Pad生命周期相同，但不容器的生命周期丌相關
Kubernetes支持多種類型的Volume，並且一個Pod可以同時使用任意多個Volume
Volume類型包括:
- EmptyDir：Pod分配時創建， K8S自動分配，當Pod被移除數據被清空。用於臨時空間等。
- hostPath：為Pod上掛載宿主機目錄。用於持久化數據。
- nfs：掛載相應磁盤資源。

EmptyDir實驗

cat >emptyDir.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: busybox-empty
spec:
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/busybox/
      name: cache-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/busybox/index.html;sleep 3;done"]
  volumes:
  - name: cache-volume
    emptyDir: {}
EOF

hostPath實驗

1.發現的問題：
- 目錄必須存在才能創建
- POD不固定會創建在哪個Node上，數據不統一

2.type類型說明
https://kubernetes.io/docs/concepts/storage/volumes/#hostpath

DirectoryOrCreate  目錄不存在就自動創建
Directory	   目錄必須存在
FileOrCreate	   文件不存在則創建
File		   文件必須存在

3.根據Node標簽選擇POD創建在指定的Node上
方法1: 直接選擇Node節點名稱
apiVersion: v1
kind: Pod
metadata:
  name: busybox-nodename
spec:
  nodeName: node2
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/pod/
      name: hostpath-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/pod/index.html;sleep 3;done"]
  volumes:
  - name: hostpath-volume
    hostPath:
      path: /data/node/
      type: DirectoryOrCreate 


方法2: 根據Node標簽選擇Node節點
kubectl label nodes node3 disktype=SSD

apiVersion: v1
kind: Pod
metadata:
  name: busybox-nodename
spec:
  nodeSelector:
    disktype: SSD
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/pod/
      name: hostpath-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/pod/index.html;sleep 3;done"]
  volumes:
  - name: hostpath-volume
    hostPath:
      path: /data/node/
      type: DirectoryOrCreate 


4.實驗-編寫mysql的持久化deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-dp
  namespace: default
spec:
  selector:
    matchLabels:
      app: mysql 
  replicas: 1
  template: 
    metadata:
      name: mysql-pod
      namespace: default
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql-pod
        image: mysql:5.7 
        ports:
        - name: mysql-port
          containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456" 
        volumeMounts:
        - mountPath: /var/lib/mysql
          name: mysql-volume
      volumes:
      - name: mysql-volume
        hostPath:
          path: /data/mysql
          type: DirectoryOrCreate 
      nodeSelector:
        disktype: SSD

PV和PVC

1.master節點安裝nfs
yum install nfs-utils -y
mkdir /data/nfs-volume -p
vim /etc/exports
/data/nfs-volume 10.0.0.0/24(rw,async,no_root_squash,no_all_squash)
systemctl start rpcbind
systemctl start nfs
showmount -e 127.0.0.1

2.所有node節點安裝nfs
yum install nfs-utils.x86_64 -y
showmount -e 10.0.0.11

3.編寫並創建nfs-pv資源
cat >nfs-pv.yaml <<EOF
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv01
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: nfs
  nfs:
    path: /data/nfs-volume/mysql
    server: 10.0.0.11
EOF

kubectl create -f nfs-pv.yaml
kubectl get persistentvolume

3.創建mysql-pvc
cat >mysql-pvc.yaml <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pvc 
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: nfs
EOF
kubectl create -f mysql-pvc.yaml
kubectl get pvc

4.創建mysql-deployment
cat >mysql-dp.yaml <<EOF
apiVersion: apps/v1
kind: Deployment 
metadata:
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"
        volumeMounts:
        - name: mysql-pvc
          mountPath: /var/lib/mysql
        - name: mysql-log
          mountPath: /var/log/mysql
      volumes:
      - name: mysql-pvc
        persistentVolumeClaim:
          claimName: mysql-pvc
      - name: mysql-log
        hostPath:
          path: /var/log/mysql
      nodeSelector:
        disktype: SSD
EOF

kubectl create -f mysql-dp.yaml
kubectl get pod -o wide 

5.測試方法
1.創建nfs-pv
2.創建mysql-pvc
3.創建mysql-deployment並掛載mysq-pvc
4.登陸到mysql的pod里創建一個數據庫
5.將這個pod刪掉，因為deployment設置了副本數，所以會自動再創建一個新的pod
6.登錄這個新的pod，查看剛才創建的數據庫是否依然能看到
7.如果仍然能看到，則說明數據是持久化保存的

6.accessModes字段說明
ReadWriteOnce 單路讀寫
ReadOnlyMany  多路只讀
ReadWriteMany 多路讀寫
resources 資源的限制，比如至少5G

7.volumeName精確匹配
#capacity 限制存儲空間大小
#reclaim policy pv的回收策略
#retain  pv被解綁后上面的數據仍保留
#recycle pv上的數據被釋放
#delete  pvc和pv解綁后pv就被刪除
備注：用戶在創建pod所需要的存儲空間時，前提是必須要有pv存在
才可以，這樣就不符合自動滿足用戶的需求，而且之前在k8s 9.0
版本還可刪除pv，這樣造成數據不安全性

configMap資源

1.為什么要用configMap？
將配置文件和POD解耦

2.congiMap里的配置文件是如何存儲的？
鍵值對
key:value
文件名:配置文件的內容

3.configMap支持的配置類型
  直接定義的鍵值對 
  基於文件創建的鍵值對

4.configMap創建方式
  命令行
  資源配置清單 

5.configMap的配置文件如何傳遞到POD里
  變量傳遞
  數據卷掛載

6.命令行創建configMap
kubectl create configmap --help

kubectl create configmap nginx-config --from-literal=nginx_port=80 --from-literal=server_name=nginx.cookzhang.com

kubectl get cm
kubectl describe cm nginx-config 


7.POD環境變量形式引用configMap
kubectl explain pod.spec.containers.env.valueFrom.configMapKeyRef

cat >nginx-cm.yaml <<EOF
apiVersion: v1
kind: Pod
metadata: 
  name: nginx-cm
spec:
  containers:
  - name: nginx-pod
    image: nginx:1.14.0
    ports:
    - name: http 
      containerPort: 80
    env:
    - name: NGINX_PORT
      valueFrom:
        configMapKeyRef:
          name: nginx-config
          key: nginx_port
    - name: SERVER_NAME
      valueFrom:
        configMapKeyRef:
          name: nginx-config
          key: server_name 
EOF
kubectl create -f nginx-cm.yaml

8.查看pod是否引入了變量
[root@node1 ~/confimap]# kubectl exec -it nginx-cm /bin/bash
root@nginx-cm:~# echo ${NGINX_PORT}
80
root@nginx-cm:~# echo ${SERVER_NAME}
nginx.cookzhang.com
root@nginx-cm:~# printenv |egrep "NGINX_PORT|SERVER_NAME"
NGINX_PORT=80
SERVER_NAME=nginx.cookzhang.com

注意：
變量傳遞的形式，修改confMap的配置，POD內並不會生效
因為變量只有在創建POD的時候才會引用生效，POD一旦創建好，環境變量就不變了


8.文件形式創建configMap
創建配置文件：
cat >www.conf <<EOF
server {
        listen       80;
        server_name  www.cookzy.com;
        location / {
            root   /usr/share/nginx/html/www;
            index  index.html index.htm;
        }
    }
EOF

創建configMap資源：
kubectl create configmap nginx-www --from-file=www.conf=./www.conf 

查看cm資源
kubectl get cm
kubectl describe cm nginx-www

編寫pod並以存儲卷掛載模式引用configMap的配置
cat >nginx-cm-volume.yaml <<EOF
apiVersion: v1
kind: Pod
metadata: 
  name: nginx-cm
spec:
  containers:
  - name: nginx-pod
    image: nginx:1.14.0
    ports:
    - name: http 
      containerPort: 80

    volumeMounts:
    - name: nginx-www
      mountPath: /etc/nginx/conf.d/

  volumes:
  - name: nginx-www
    configMap:
     name: nginx-www
     items: 
     - key: www.conf
       path: www.conf
EOF

測試：
1.進到容器內查看文件
kubectl exec -it nginx-cm /bin/bash
cat /etc/nginx/conf.d/www.conf 
2.動態修改configMap
kubectl edit cm nginx-www

3.再次進入容器內觀察配置會不會自動更新
cat /etc/nginx/conf.d/www.conf 
nginx -T

安全認證和RBAC

API Server是訪問控制的唯一入口

在k8s平台上的操作對象都要經歷三種安全相關的操作
1.認證操作
  http協議 token 認證令牌 
  ssl認證  kubectl需要證書雙向認證
2.授權檢查
  RBAC  基於角色的訪問控制 
3.准入控制
  進一步補充授權機制，一般在創建，刪除，代理操作時作補充

k8s的api賬戶分為2類
  1.實實在在的用戶 人類用戶 userAccount
  2.POD客戶端 serviceAccount 默認每個POD都有認真信息

RBAC就要角色的訪問控制
  你這個賬號可以擁有什么權限
  
以traefik舉例：
1.創建了賬號 ServiceAccount:traefik-ingress-controller
2.創建角色   ClusterRole:   traefik-ingress-controller
  Role  POD相關的權限
  ClusterRole namespace級別操作 
3.將賬戶和權限角色進行綁定     traefik-ingress-controller
  RoleBinding
  ClusterRoleBinding
4.創建POD時引用ServiceAccount
  serviceAccountName: traefik-ingress-controller


注意！！！
kubeadm安裝的k8s集群，證書默認只有1年

k8s dashboard

1.官方項目地址
https://github.com/kubernetes/dashboard

2.下載配置文件
wget https://raw.githubusercontent.com/kubernetes/dashboard/v2.0.0-rc5/aio/deploy/recommended.yaml

3.修改配置文件
 39 spec:
 40   type: NodePort
 41   ports:
 42     - port: 443
 43       targetPort: 8443
 44       nodePort: 30000

4.應用資源配置
kubectl create -f recommended.yaml

5.創建管理員賬戶並應用
cat > dashboard-admin.yaml<<EOF
apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kubernetes-dashboard
EOF
kubectl create -f dashboard-admin.yaml

6.查看資源並獲取token
kubectl get pod -n kubernetes-dashboard -o wide
kubectl get svc -n kubernetes-dashboard
kubectl get secret  -n kubernetes-dashboard
kubectl -n kubernetes-dashboard describe secret $(kubectl -n kubernetes-dashboard get secret | grep admin-user | awk '{print $1}')

7.瀏覽器訪問
https://10.0.0.11:30000
google瀏覽器打不開就換火狐瀏覽器
黑科技 
this is unsafe

研究的方向

0.namespace
1.ServiceAccount
2.Service
3.Secret
4.configMap
5.RBAC
6.Deployment

重啟k8s二進制安裝(kubeadm)需要重啟組件

1.kube-apiserver
2.kube-proxy
3.kube-sechduler
4.kube-controller
5.etcd
6.coredns
7.flannel
8.traefik
9.docker
10.kubelet