Kubernetes DNS不解析外部地址

Question

我的kubernetes集群和DNS有问题。

我们最近更新到RHEL7.5，其中一台机器是Master。一旦它恢复正常，大部分工作正常，但我只是注意到，来自集群的外部连接无法解决。内部交流效果很好。

以下是busybox nslookup结果：

kubectl exec -ti busybox -- nslookup kubernetes.default
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

nslookup: can't resolve 'kubernetes.default'

库伯恩斯地位

Name:              kube-dns
Namespace:         kube-system
Labels:            k8s-app=kube-dns
                   kubernetes.io/cluster-service=true
                   kubernetes.io/name=KubeDNS
Annotations:       <none>
Selector:          k8s-app=kube-dns
Type:              ClusterIP
IP:                10.96.0.10
Port:              dns  53/UDP
TargetPort:        53/UDP
Endpoints:         10.32.0.18:53
Port:              dns-tcp  53/TCP
TargetPort:        53/TCP
Endpoints:         10.32.0.18:53
Session Affinity:  None
Events:            <none>

所有的吊舱都说他们站起来了

NAME                        READY     STATUS    RESTARTS   AGE
kube-dns-86f4d74b45-9m292   3/3       Running   26         44d

库伯恩斯豆荚里的最新原木

I0523 15:59:14.291623       1 logs.go:41] skydns: ready for queries on cluster.local. for tcp://0.0.0.0:10053 [rcache 0]
I0523 15:59:14.291638       1 logs.go:41] skydns: ready for queries on cluster.local. for udp://0.0.0.0:10053 [rcache 0]
I0523 15:59:14.791440       1 dns.go:170] Initialized services and endpoints from apiserver
I0523 15:59:14.791560       1 server.go:135] Setting up Healthz Handler (/readiness)
I0523 15:59:14.791579       1 server.go:140] Setting up cache handler (/cache)
I0523 15:59:14.791588       1 server.go:126] Status HTTP port 8081
I0523 16:48:05.175159       1 dns.go:555] Could not find endpoints for service "kube-prometheus-exporter-kube-controller-manager" in namespace "kube-system". DNS records will be created once endpoints show up.
I0523 16:48:05.236418       1 dns.go:555] Could not find endpoints for service "kube-prometheus-exporter-kube-dns" in namespace "kube-system". DNS records will be created once endpoints show up.
I0523 16:48:05.252139       1 dns.go:555] Could not find endpoints for service "kube-prometheus-exporter-kube-etcd" in namespace "kube-system". DNS records will be created once endpoints show up.
I0523 16:48:05.264292       1 dns.go:555] Could not find endpoints for service "kube-prometheus-exporter-kube-scheduler" in namespace "kube-system". DNS records will be created once endpoints show up.
I0524 13:04:38.008038       1 logs.go:41] skydns: failure to forward request "read udp 10.32.0.18:48431->10.101.24.100:53: i/o timeout"
I0524 13:04:41.973900       1 logs.go:41] skydns: failure to forward request "read udp 10.32.0.18:45738->10.101.24.100:53: i/o timeout"
I0524 17:26:54.056913       1 logs.go:41] skydns: failure to forward request "read udp 10.32.0.18:52242->10.101.24.100:53: i/o timeout"
I0524 18:28:16.762002       1 logs.go:41] skydns: failure to forward request "read udp 10.32.0.18:43051->10.101.24.100:53: i/o timeout"
I0524 18:28:20.762912       1 logs.go:41] skydns: failure to forward request "read udp 10.32.0.18:57624->10.101.24.100:53: i/o timeout"

我假设这与重新启动有关。

Kubernetes:版本1.10.3

DNS: kube-dns

网络: Weavenet

主机操作系统: RHEL 7.5

任何帮助都会很好。

谢谢

Answer 1

不确定您的升级细节，但检查看看您的kube版本是否改变了当您升级您的操作系统。解决外部名称服务的kube版本1.14.9有一个问题。您需要将kube回滚到以前的版本，或者升级到1.14.10。

见本期：https://github.com/kubernetes/kops/issues/4986