Kubernetes DNS 不解析外部地址

Kubernetes DNS not resolving external addresses

我的 kubernetes 集群和 DNS 有问题。

我们最近更新到 RHEL 7.5,其中一台机器是 Master。一旦它重新联机,大多数都可以正常工作,但我只是注意到来自集群的外部连接无法解析。内部沟通效果很好。

这是 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'

kubedns 状态

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 pods 都说他们起来了

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

来自 kubedns 的最新日志 pods

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"

我假设这与重启有关。

Kubernetes:版本 1.10.3

DNS:kube-dns

网络:Weavenet

主机OS:RHEL 7.5

任何帮助都会很棒。

谢谢

不确定升级的详细信息,但请检查升级 OS 时您的 kube-dns 版本是否更改。 kube-dns 1.14.9 版本在解析外部名称服务时存在问题。您需要将 kube-dns 回滚到以前的版本,或者升级到 1.14.10。

看到这个问题:https://github.com/kubernetes/kops/issues/4986