K8s深入了解

Ingress控制器介绍

1.没有ingress之前，pod对外提供服务只能通过NodeIP:NodePort的形式，但是这种形式有缺点，一个节点上的PORT不能重复利用。比如某个服务占用了80，那么其他服务就不能在用这个端口了。
2.NodePort是4层代理，不能解析7层的http，不能通过域名区分流量
3.为了解决这个问题，我们需要用到资源控制器叫Ingress，作用就是提供一个统一的访问入口。工作在7层
4.虽然我们可以使用nginx/haproxy来实现类似的效果，但是传统部署不能动态的发现我们新创建的资源，必须手动修改配置文件并重启。
5.适用于k8s的ingress控制器主流的有ingress-nginx和traefik
6.ingress-nginx == nginx + go --> deployment部署 
7.traefik有一个UI界面 

安装部署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.应用资源配置
kubectl create -f ./

5.查看并访问
kubectl -n kube-system get svc 

创建traefik的web-ui的ingress规则

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

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


2.ingress写法:
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.访问测试：
traefik.ui.com

ingress实验

1.实验目标
未使用ingress之前只能通过IP+端口访问：
tomcat 8080
nginx  8090

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

2.创建2个pod和svc
mysql-dp.yaml  
mysql-svc.yaml 
tomcat-dp.yaml  
tomcat-svc.yaml

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

3.创建ingress控制器资源配置清单并应用
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.查看创建的资源
kubectl get svc
kubectl get ingresses
kubectl describe ingresses traefik-nginx
kubectl describe ingresses traefik-tomcat

5.访问测试
traefik.nginx.com
traefik.tomcat.com

数据持久化

Volume介绍

Volume是Pad中能够被多个容器访问的共享目录
Kubernetes中的Volume不Pad生命周期相同，但不容器的生命周期丌相关
Kubernetes支持多种类型的Volume，并且一个Pod可以同时使用任意多个Volume
Volume类型包括:
- EmptyDir：Pod分配时创建， K8S自动分配，当Pod被移除数据被清空。用于临时空间等。
- hostPath：为Pod上挂载宿主机目录。用于持久化数据。
- nfs：挂载相应磁盘资源。

EmptyDir实验

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实验

1.发现的问题：
- 目录必须存在才能创建
- POD不固定会创建在哪个Node上，数据不统一

2.type类型说明
https://kubernetes.io/docs/concepts/storage/volumes/#hostpath

DirectoryOrCreate  目录不存在就自动创建
Directory      目录必须存在
FileOrCreate       文件不存在则创建
File           文件必须存在

3.根据Node标签选择POD创建在指定的Node上
方法1: 直接选择Node节点名称
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: 根据Node标签选择Node节点
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.实验-编写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节点安装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节点安装nfs
yum install nfs-utils.x86_64 -y
showmount -e 10.0.0.11

3.编写并创建nfs-pv资源
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.创建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.创建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.测试方法
1.创建nfs-pv
2.创建mysql-pvc
3.创建mysql-deployment并挂载mysq-pvc
4.登陆到mysql的pod里创建一个数据库
5.将这个pod删掉，因为deployment设置了副本数，所以会自动再创建一个新的pod
6.登录这个新的pod，查看刚才创建的数据库是否依然能看到
7.如果仍然能看到，则说明数据是持久化保存的

6.accessModes字段说明
ReadWriteOnce 单路读写
ReadOnlyMany  多路只读
ReadWriteMany 多路读写
resources 资源的限制，比如至少5G

7.volumeName精确匹配
#capacity 限制存储空间大小
#reclaim policy pv的回收策略
#retain  pv被解绑后上面的数据仍保留
#recycle pv上的数据被释放
#delete  pvc和pv解绑后pv就被删除
备注：用户在创建pod所需要的存储空间时，前提是必须要有pv存在
才可以，这样就不符合自动满足用户的需求，而且之前在k8s 9.0
版本还可删除pv，这样造成数据不安全性

configMap资源

1.为什么要用configMap？
将配置文件和POD解耦

2.congiMap里的配置文件是如何存储的？
键值对
key:value
文件名:配置文件的内容

3.configMap支持的配置类型
  直接定义的键值对 
  基于文件创建的键值对

4.configMap创建方式
  命令行
  资源配置清单 

5.configMap的配置文件如何传递到POD里
  变量传递
  数据卷挂载

6.命令行创建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环境变量形式引用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是否引入了变量
[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：
变量传递的形式，修改confMap的配置，POD内并不会生效
因为变量只有在创建POD的时候才会引用生效，POD一旦创建好，环境变量就不变了


8.文件形式创建configMap
创建配置文件：
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

创建configMap资源：
kubectl create configmap nginx-www --from-file=www.conf=./www.conf 

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

编写pod并以存储卷挂载模式引用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

测试：
1.进到容器内查看文件
kubectl exec -it nginx-cm /bin/bash
cat /etc/nginx/conf.d/www.conf 
2.动态修改configMap
kubectl edit cm nginx-www

3.再次进入容器内观察配置会不会自动更新
cat /etc/nginx/conf.d/www.conf 
nginx -T

安全认证和RBAC

API Server是访问控制的唯一入口

在k8s平台上的操作对象都要经历三种安全相关的操作
1.认证操作
  http协议 token 认证令牌 
  ssl认证  kubectl需要证书双向认证
2.授权检查
  RBAC  基于角色的访问控制 
3.准入控制
  进一步补充授权机制，一般在创建，删除，代理操作时作补充

k8s的api账户分为2类
  1.实实在在的用户 人类用户 userAccount
  2.POD客户端 serviceAccount 默认每个POD都有认真信息

RBAC就要角色的访问控制
  你这个账号可以拥有什么权限
  
以traefik举例：
1.创建了账号 ServiceAccount:traefik-ingress-controller
2.创建角色   ClusterRole:   traefik-ingress-controller
  Role  POD相关的权限
  ClusterRole namespace级别操作 
3.将账户和权限角色进行绑定     traefik-ingress-controller
  RoleBinding
  ClusterRoleBinding
4.创建POD时引用ServiceAccount
  serviceAccountName: traefik-ingress-controller


注意！！！
kubeadm安装的k8s集群，证书默认只有1年

k8s dashboard

1.官方项目地址
https://github.com/kubernetes/dashboard

2.下载配置文件
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.应用资源配置
kubectl create -f recommended.yaml

5.创建管理员账户并应用
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.查看资源并获取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.浏览器访问
https://10.0.0.11:30000
google浏览器打不开就换火狐浏览器
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

重启k8s二进制安装(kubeadm)需要重启组件

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

原文链接:https://www.cnblogs.com/1naonao/p/12443951.html
如有疑问请与原作者联系

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