我正在运行一个具有主节点和2个工作节点的kubernetes集群。

root@kube-master:~# kubectl get nodes
NAME           STATUS   ROLES    AGE     VERSION
kube-master    Ready    master   4d19h   v1.14.3
kube-node-01   Ready    <none>   4d18h   v1.14.3
kube-node-02   Ready    <none>   6h3m    v1.14.3

现在,我的traefik入口 Controller 无法解析dns查询。
/ # nslookup acme-v02.api.letsencrypt.org
nslookup: can't resolve '(null)': Name does not resolve

Name:      acme-v02.api.letsencrypt.org
Address 1: <my.public.ip> mail.xxx.xxx

现在,在opnsense框上带有tcpdump,我收到的查询都带有内部搜索域,该域附加解析为我的公共(public)IP,这是错误的。

但是由于某些原因...将忙碌的测试箱旋转起来是可行的...
/ # nslookup acme-v02.api.letsencrypt.org
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      acme-v02.api.letsencrypt.org
Address 1: 2a02:26f0:ef:197::3a8e g2a02-26f0-00ef-0197-0000-0000-0000-3a8e.deploy.static.akamaitechnologies.com
Address 2: 2a02:26f0:ef:181::3a8e g2a02-26f0-00ef-0181-0000-0000-0000-3a8e.deploy.static.akamaitechnologies.com
Address 3: 104.74.120.43 a104-74-120-43.deploy.static.akamaitechnologies.com

/etc/resolve.conf文件都相同,但namespace
由于kubernetes 1.11 coredns成为默认的DNS解析系统。在this页面上,用coredns调试dns系统说我应该使用
root@kube-master:~# kubectl get pods --namespace=kube-system -l k8s-app=coredns
No resources found.

但这不返回任何东西!使用kube-dns会返回coredns pods !
root@kube-master:~# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME                      READY   STATUS    RESTARTS   AGE
coredns-fb8b8dccf-jmhdm   1/1     Running   5          4d19h
coredns-fb8b8dccf-tfw7v   1/1     Running   5          4d19h

这里发生了什么?!文档是否错误或群集中有东西?

最佳答案

我将展示和解释您使用nginx入口 Controller 的示例。我相信traefik入口 Controller 的情况是相同的。

因此,首先-关于kube-dnscoredns混乱,您正在描述:
这是设计使然。您可以参考github coredns is still labeled as kube-dns issue了解更多信息。

在我的集群中,我还拥有称为corednskube-dns服务,它引用具有coredns标签的k8s-app=kube-dns容器

kubectl describe service kube-dns -n kube-system
Name:              kube-dns
Namespace:         kube-system
Labels:            k8s-app=kube-dns
                   kubernetes.io/cluster-service=true
                   kubernetes.io/name=KubeDNS
Annotations:       prometheus.io/port: 9153
                   prometheus.io/scrape: true
Selector:          k8s-app=kube-dns
Type:              ClusterIP
IP:                10.96.0.10
Port:              dns  53/UDP
TargetPort:        53/UDP
Endpoints:         10.32.0.2:53,10.32.0.9:53
Port:              dns-tcp  53/TCP
TargetPort:        53/TCP
Endpoints:         10.32.0.2:53,10.32.0.9:53
Port:              metrics  9153/TCP
TargetPort:        9153/TCP
Endpoints:         10.32.0.2:9153,10.32.0.9:9153
Session Affinity:  None
Events:            <none>

kubectl get pods -n kube-system -l k8s-app=kube-dns -o wide
NAME                      READY   STATUS    RESTARTS   AGE     IP          NODE                     NOMINATED NODE   READINESS GATES
coredns-fb8b8dccf-42285   1/1     Running   0          3h26m   10.32.0.9   kubernetessandbox-1-vm   <none>           <none>
coredns-fb8b8dccf-87j5v   1/1     Running   0          3h26m   10.32.0.2   kubernetessandbox-1-vm   <none>           <none>

当我旋转新的busybox pod时-它具有/etc/resolv.conf指向服务kube-dns(10.96.0.10)并具有正确的搜索:
cat /etc/resolv.conf
search kube-system.svc.cluster.local svc.cluster.local cluster.local c.myproj.internal. google.internal.
nameserver 10.96.0.10
options ndots:5

但与此同时,我的Nginx入口 Controller Pod具有nameserver 169.254.169.254,甚至无法nslookup甚至kubernetes.default
cat /etc/resolv.conf
search c.myproj.internal. google.internal.
nameserver 169.254.169.254

不确定您在trafic pod上的/etc/resolv.conf中有什么,但是问题出在那儿。而您拥有的/etc/resolv.conf来自您的节点

如果入口使用hostNetwork,则设置dnsPolicy:ClusterFirstWithHostNet而不是dnsPolicy:ClusterFirst应该解决此问题。

dns-pod-service documentation:



从编辑nginx-ingress-controller部署后
  dnsPolicy: ClusterFirst
  hostNetwork: true


  dnsPolicy: ClusterFirstWithHostNet
  hostNetwork: true

使用所需的/etc/resolv.conf重新创建了pod:
cat /etc/resolv.conf
search kube-system.svc.cluster.local svc.cluster.local cluster.local c.myproj.internal. google.internal.
nameserver 10.96.0.10
options ndots:5

nslookup kubernetes.default
Server:         10.96.0.10
Address:        10.96.0.10#53

Name:   kubernetes.default.svc.cluster.local
Address: 10.96.0.1

与hostNetwork / dnsPolicy相关的问题和解释的网址很少。这是正确配置Traefik的重要部分:

1)Traefik on k8s not listening externally without changing deployment

2)Stack traefik question

3)Ingress with Traefik文章:
dnsPolicy: ClusterFirstWithHostNet



希望能帮助到你

关于kubernetes - 某些查询中附加了kubernetes dns搜索域,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/56737552/

10-09 02:51