k8s中的dns应用

1. 先看下dns 和 ingress相关的

[root@k8s-shanghai-master-1 k8s-cluster]# kubectl get ingress -A -o wide  | grep traefik-ingress-controller
dev-ydata   flink-reactive-jobmanager       traefik-ingress-controller   flink-reactive-web.dev.eu-central-1.yealinkops.com                                                        80        15h
dev-ydata   kafka-manager                   traefik-ingress-controller   kafka-manager-ydata.dev.eu-central-1.yealinkops.com                                                       80        15h
dev-ydata   ydata-web                       traefik-ingress-controller   ydata-web.dev.eu-central-1.yealinkops.com                                                                 80        15h
pts-core    common-kibana                   traefik-ingress-controller   pts-kibana.ylops.com                                                                                      80        26m
pts-core    pts-foundation                  traefik-ingress-controller   pts-foundation.ylops.com                                                                                  80        15m
pts-core    pts-processor                   traefik-ingress-controller   pts-processor.ylops.com                                                                                   80        14m
pts-core    pts-web                         traefik-ingress-controller   worklink.ylops.com                                                                                        80        14m
pts-core    rocketmq-console                traefik-ingress-controller   pts-mqconsole.ylops.com                                                                                   80        32m
ydocs-qa    rocketmq-console                traefik-ingress-controller   ydocs-mqconsole-qa.ylops.com                                                                              80        15h
ydocs-qa    yl-cooperation-document         traefik-ingress-controller   ydocs-qa.ylops.com                                                                                        80        13h


[root@k8s-shanghai-master-1 k8s-cluster]# kubectl get svc -A -o wide | grep traefik-ingress
kube-system            traefik-ingress-service                   LoadBalancer   172.27.38.38     172.17.99.15     80:31599/TCP,8080:30196/TCP,443:31646/TCP                 4d16h   app=traefik-ingress-lb

所有通过ingress来负载均衡的服务的域名解析都是基于ingress的svc external ip来访问的

集群内部可以基于ingress 查到域名和traefik-ingress-controller的关联。
但是 域名和external ip（fip）的解析记录是在集群外部统一维护的，一般每个办公区域都有一个统一的dns服务。
比如 coredns，dnsmasq，每个模拟的可用区的dns记录，都统一在外部的dns服务内解析。