K8S核心插件-ingress(服务暴露)控制器-traefik

1 K8S两种服务暴露方法

前面通过coredns在k8s集群内部做了serviceNAME和serviceIP之间的自动映射,使得不需要记录service的IP地址,只需要通过serviceNAME就能访问POD
但是在K8S集群外部,显然是不能通过serviceNAME或serviceIP来解析服务的
要在K8S集群外部来访问集群内部的资源,需要用到服务暴露功能

1.1 K8S常用的两种服务暴露方法

1. 使用NodePort型的Service
   nodeport型的service原理相当于端口映射，将容器内的端口映射到宿主机上的某个端口。
   K8S集群不能使用ipvs的方式调度,必须使用iptables,且只支持rr模式

2. 使用Ingress资源
   Ingress是K8S API标准资源之一,也是核心资源
   是一组基于域名和URL路径的规则,把用户的请求转发至指定的service资源
   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'

1.2 Ingress控制器是什么

可以理解为一个简化版本的nginx
Ingress控制器是能够为Ingress资源健康某套接字,然后根据ingress规则匹配机制路由调度流量的一个组件
只能工作在七层网络下，建议暴露http, https可以使用前端nginx来做证书方面的卸载

我们使用的ingress控制器为Traefik

traefik：GITHUB官方地址

2 部署traefik

同样的,现在7.200完成docker镜像拉取和配置清单创建,然后再到任意master节点执行配置清单

2.1 准备docker镜像

docker pull traefik:v1.7.2-alpine
docker tag  traefik:v1.7.2-alpine harbor.zq.com/public/traefik:v1.7.2
docker push harbor.zq.com/public/traefik:v1.7.2

2.2 创建资源清单

mkdir -p /data/k8s-yaml/traefik

2.2.1 rbac授权清单

cat >/data/k8s-yaml/traefik/rbac.yaml <<EOF
apiVersion: v1
kind: ServiceAccount
metadata:name: traefik-ingress-controllernamespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:name: traefik-ingress-controller
rules:- apiGroups:- ""resources:- services- endpoints- secretsverbs:- get- list- watch- apiGroups:- extensionsresources:- ingressesverbs:- get- list- watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:name: traefik-ingress-controller
roleRef:apiGroup: rbac.authorization.k8s.iokind: ClusterRolename: traefik-ingress-controller
subjects:
- kind: ServiceAccountname: traefik-ingress-controllernamespace: kube-system
EOF

2.2.2 delepoly资源清单

cat >/data/k8s-yaml/traefik/ds.yaml <<EOF
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:name: traefik-ingressnamespace: kube-systemlabels:k8s-app: traefik-ingress
spec:template:metadata:labels:k8s-app: traefik-ingressname: traefik-ingressspec:serviceAccountName: traefik-ingress-controllerterminationGracePeriodSeconds: 60containers:- image: harbor.zq.com/public/traefik:v1.7.2name: traefik-ingressports:- name: controllercontainerPort: 80hostPort: 81- name: admin-webcontainerPort: 8080securityContext:capabilities:drop:- ALLadd:- NET_BIND_SERVICEargs:- --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
EOF

2.2.3 service清单

cat >/data/k8s-yaml/traefik/svc.yaml <<EOF
kind: Service
apiVersion: v1
metadata:name: traefik-ingress-servicenamespace: kube-system
spec:selector:k8s-app: traefik-ingressports:- protocol: TCPport: 80name: controller- protocol: TCPport: 8080name: admin-web
EOF

2.2.4 ingress清单

cat >/data/k8s-yaml/traefik/ingress.yaml <<EOF
apiVersion: extensions/v1beta1
kind: Ingress
metadata:name: traefik-web-uinamespace: kube-systemannotations:kubernetes.io/ingress.class: traefik
spec:rules:- host: traefik.zq.comhttp:paths:- path: /backend:serviceName: traefik-ingress-serviceservicePort: 8080
EOF

2.3 创建资源

2.3.1 任意节点上创建资源

kubectl create -f http://k8s-yaml.zq.com/traefik/rbac.yaml
kubectl create -f http://k8s-yaml.zq.com/traefik/ds.yaml
kubectl create -f http://k8s-yaml.zq.com/traefik/svc.yaml
kubectl create -f http://k8s-yaml.zq.com/traefik/ingress.yaml

2.3.2 在前端nginx上做反向代理

在7.11和7.12上,都做反向代理,将泛域名的解析都转发到traefik上去

cat >/etc/nginx/conf.d/zq.com.conf <<'EOF'
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 *.zq.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;
}