4.kubernetes的服务暴露插件-Traefik

1.kubernetes的服务暴露插件-Traefik

K8S的DNS实现了服务在集群"内"被自动发现，如何使得服务在Kuberneters集群"外"被使用和访问呢，有二种方法

1)使用NodePort型的Service

​ 注意：无法使用kube-proxy的ipvs模型，只能使用iptables模型

2)使用Ingress资源

注意：Ingress只能调度并暴露7层应用，特指http和https协议，一般建议用在http协议上

Ingress是K8S API的标准资源类型之一，也是一种核心资源。它其实就是一组基于域名和URL路径，把用户的请求转发至指定Service资源的规则

可以将集群外部的请求流量，转发至集群内部，从而实现 “服务暴露”

Ingress控制器是能够为Ingress资源监听某套接字，然后根据Ingress规则匹配机制路由调度流量的一个组件

说白了，Ingress就是一个简化版的Nginx+ 一段go脚本而已

常用的Ingress控制器的实现软件：

Ingress-nginx

HAProxy

Traefik

同nginx相比，traefik能够自动感知后端容器变化，从而实现自动服务发现。

traefik部署在k8s上分为daemonset和deployment两种方式

daemonset能确定有哪些node在运行tracfik，所以可以确定的知道后端IP，但是不能方便的伸缩

deployment可以更方便的伸缩，但是不能确定有哪些node在运行traefik，所以不能确定的知道后端IP

一般部署两种不同类型的tracfik：

​ 面向内部(internal)服务的traefik，建议可以使用deployment的方式

​ 面向外部(external)服务的traefik，建议可以使用daemonset的方式

建议使用traffic-type标签

​ traffic-type: external

​ traffic-type: inernal

traefik相应地使用lableSelector

​ traffic-type=internal

​ traffic-type=external

1.1 部署traefik

在hdss7-200.host.com上下载traefik镜像

[root@hdss7-200 ~]# docker pull traefik:v1.7.2-alpine
[root@hdss7-200 ~]# docker images|grep traefik
[root@hdss7-200 ~]# docker tag add5fac61ae5 harbor.od.com/public/traefik:v1.7.2
[root@hdss7-200 ~]# docker push  harbor.od.com/public/traefik:v1.7.2

1.2 在hdss7-200.host.com上准备资源配置清单

[root@hdss7-200 k8s-yaml]# pwd
/data/k8s-yaml
[root@hdss7-200 k8s-yaml]# mkdir traefik
[root@hdss7-200 k8s-yaml]# cd traefik/

rbac.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: traefik-ingress-controller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
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

ds.ymal

apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: traefik-ingress
  namespace: kube-system
  labels:
    k8s-app: traefik-ingress
spec:
  template:
    metadata:
      labels:
        k8s-app: traefik-ingress
        name: traefik-ingress
    spec:
      serviceAccountName: traefik-ingress-controller
      terminationGracePeriodSeconds: 60
      containers:
      - image: harbor.od.com/public/traefik:v1.7.2
        name: traefik-ingress
        ports:
        - name: controller
          containerPort: 80
          hostPort: 81
        - name: admin-web
          containerPort: 8080
        securityContext:
          capabilities:
            drop:
            - ALL
            add:
            - NET_BIND_SERVICE
        args:
        - --api
        - --kubernetes
        - --logLevel=INFO
        - --insecureskipverify=true
        - --kubernetes.endpoint=https://10.4.7.10:7443
        - --accesslog
        - --accesslog.filepath=/var/log/traefik_access.log
        - --traefiklog
        - --traefiklog.filepath=/var/log/traefik.log
        - --metrics.prometheus

svc.yaml

kind: Service
apiVersion: v1
metadata:
  name: traefik-ingress-service
  namespace: kube-system
spec:
  selector:
    k8s-app: traefik-ingress
  ports:
    - protocol: TCP
      port: 80
      name: controller
    - protocol: TCP
      port: 8080
      name: admin-web

ingress.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: traefik-web-ui
  namespace: kube-system
  annotations:
    kubernetes.io/ingress.class: traefik
spec:
  rules:
  - host: traefik.od.com
    http:
      paths:
      - path: /
        backend:
          serviceName: traefik-ingress-service
          servicePort: 8080

1.4 应用yaml资源配置清单创建traefik

在master主机(21、22)任意一台执行

[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.od.com/traefik/rbac.yaml
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.od.com/traefik/ds.yaml
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.od.com/traefik/svc.yaml
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.od.com/traefik/ingress.yaml

1.5 检查创建资源

[root@hdss7-21 ~]# kubectl get pods -n kube-system

1.6 解析域名

[root@hdss7-11 ~]# cat /var/named/od.com.zone
$ORIGIN od.com.
$TTL 600	; 10 minutes
@   		IN SOA	dns.od.com. dnsadmin.od.com. (
				2021123104 ; serial
				10800      ; refresh (3 hours)
				900        ; retry (15 minutes)
				604800     ; expire (1 week)
				86400      ; minimum (1 day)
				)
				NS   dns.od.com.
$TTL 60	; 1 minute
dns                A    10.4.7.11
harbor             A    10.4.7.200
k8s-yaml           A    10.4.7.200
traefik            A    10.4.7.10

1.7 配置反向代理

[root@hdss7-11 ~]# vi /etc/nginx/conf.d/od.com.conf
upstream default_backend_traefik {
    server 10.4.7.21:81    max_fails=3 fail_timeout=10s;
    server 10.4.7.22:81    max_fails=3 fail_timeout=10s;
}
server {
    server_name *.od.com;
  
    location / {
        proxy_pass http://default_backend_traefik;
        proxy_set_header Host       $http_host;
        proxy_set_header x-forwarded-for $proxy_add_x_forwarded_for;
    }
}
[root@hdss7-11 ~]# nginx -t
[root@hdss7-11 ~]# nginx -s reload

1.8 浏览器访问

http://traefik.od.com/