Error getting ConfigMap kube-system:kube-dns err: configmaps “kube-dns“ not found

2024-03-26 22:47:04

问题：
dns不通

[root@k8s-master ~]# kubectl exec -it busyboxx sh
/ # nslookup nginx
Server:    10.254.230.254
Address 1: 10.254.230.254

nslookup: can't resolve 'nginx'
/ # cat /etc/resolv.conf 
search default.svc.cluster.local svc.cluster.local cluster.local
nameserver 10.254.230.254
nameserver 8.8.8.8
options ndots:5

查看pod日志

[root@k8s-master ~]# kubectl logs -f kube-dns-3204099596-x7vdj -c kubedns -n kube-system
I0613 20:15:12.651122       1 dns.go:42] version: v1.6.0-alpha.0.680+3872cb93abf948-dirty
I0613 20:15:12.651262       1 server.go:107] Using http://192.168.150.61:8080 for kubernetes master, kubernetes API: v1
I0613 20:15:12.651550       1 server.go:68] Using configuration read from ConfigMap: kube-system:kube-dns
I0613 20:15:12.651599       1 server.go:113] FLAG: --alsologtostderr="false"
I0613 20:15:12.651613       1 server.go:113] FLAG: --config-map="kube-dns"
I0613 20:15:12.651620       1 server.go:113] FLAG: --config-map-namespace="kube-system"
I0613 20:15:12.651626       1 server.go:113] FLAG: --dns-bind-address="0.0.0.0"
I0613 20:15:12.651630       1 server.go:113] FLAG: --dns-port="10053"
I0613 20:15:12.651637       1 server.go:113] FLAG: --domain="cluster.local."
I0613 20:15:12.651645       1 server.go:113] FLAG: --federations=""
I0613 20:15:12.651651       1 server.go:113] FLAG: --healthz-port="8081"
I0613 20:15:12.651656       1 server.go:113] FLAG: --kube-master-url="http://192.168.150.61:8080"
I0613 20:15:12.651662       1 server.go:113] FLAG: --kubecfg-file=""
I0613 20:15:12.651666       1 server.go:113] FLAG: --log-backtrace-at=":0"
I0613 20:15:12.651673       1 server.go:113] FLAG: --log-dir=""
I0613 20:15:12.651679       1 server.go:113] FLAG: --log-flush-frequency="5s"
I0613 20:15:12.651685       1 server.go:113] FLAG: --logtostderr="true"
I0613 20:15:12.651691       1 server.go:113] FLAG: --stderrthreshold="2"
I0613 20:15:12.651695       1 server.go:113] FLAG: --v="0"
I0613 20:15:12.651700       1 server.go:113] FLAG: --version="false"
I0613 20:15:12.651707       1 server.go:113] FLAG: --vmodule=""
I0613 20:15:12.651756       1 server.go:155] Starting SkyDNS server (0.0.0.0:10053)
I0613 20:15:12.666762       1 server.go:165] Skydns metrics enabled (/metrics:10055)
I0613 20:15:12.669465       1 logs.go:41] skydns: ready for queries on cluster.local. for tcp://0.0.0.0:10053 [rcache 0]
I0613 20:15:12.669518       1 logs.go:41] skydns: ready for queries on cluster.local. for udp://0.0.0.0:10053 [rcache 0]
E0613 20:15:12.679738       1 sync.go:105] Error getting ConfigMap kube-system:kube-dns err: configmaps "kube-dns" not found
E0613 20:15:12.679763       1 dns.go:190] Error getting initial ConfigMap: configmaps "kube-dns" not found, starting with default values
I0613 20:15:12.684971       1 server.go:126] Setting up Healthz Handler (/readiness)
I0613 20:15:12.685000       1 server.go:131] Setting up cache handler (/cache)
I0613 20:15:12.685007       1 server.go:120] Status HTTP port 8081

解决：

[root@k8s-master ~]# cat kube-dns-cm.yml 
apiVersion: v1
kind: ConfigMap
metadata:
  name: kube-dns
  namespace: kube-system
data:
  upstreamNameservers: |
     ["1.2.3.4"]

kubectl create -f kube-dns-cm.yml

重启kube.

[root@k8s-master ~]# kubectl get deploy,po,svc,cm,ep -n kube-system
NAME              DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/kube-dns   1         1         1            1           33m

NAME                           READY     STATUS    RESTARTS   AGE
po/kube-dns-3204099596-n2w84   4/4       Unknown   0          33m
po/kube-dns-3204099596-x7vdj   4/4       Running   0          23m

NAME           CLUSTER-IP       EXTERNAL-IP   PORT(S)         AGE
svc/kube-dns   10.254.230.254   <none>        53/UDP,53/TCP   31m

NAME          DATA      AGE
cm/kube-dns   1         13m

NAME                         ENDPOINTS                   AGE
ep/kube-controller-manager   <none>                      25m
ep/kube-dns                  10.0.55.7:53,10.0.55.7:53   31m
ep/kube-scheduler            <none>                      25m

再次 nslookup

[root@k8s-master ~]# kubectl exec -it busyboxx sh
/ # nslookup kubernetes
Server:    10.254.230.254
Address 1: 10.254.230.254 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.254.0.1 kubernetes.default.svc.cluster.local
/ # nslookup nginx
Server:    10.254.230.254
Address 1: 10.254.230.254 kube-dns.kube-system.svc.cluster.local

Name:      nginx
Address 1: 10.254.213.70 nginx.default.svc.cluster.local

参考
https://cloud.tencent.com/developer/article/1649590
https://www.thinbug.com/q/43240135

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