kubedns endpoint is not working and kube-dns cannot resolve any services.

I’m using Digital Ocean kubernetes. It had been working well but now it cannot resolve any services.

It seems that the kube-dns endpoint resource is someting wrong.

Here is my logs.

$ for p in $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name); do kubectl logs --namespace=kube-system $p; done
.:53
2019-11-30T10:15:04.248Z [INFO] plugin/reload: Running configuration MD5 = 68ad62e82bb7a01ce4a04dd06bd0bf2c
2019-11-30T10:15:04.248Z [INFO] CoreDNS-1.6.2
2019-11-30T10:15:04.248Z [INFO] linux/amd64, go1.12.8, 795a3eb
CoreDNS-1.6.2
linux/amd64, go1.12.8, 795a3eb
2019-12-15T06:25:22.661Z [ERROR] plugin/errors: 2 sgp1.sonar.digitalocean.com. AAAA: read udp 10.244.0.114:50603->67.207.67.2:53: i/o timeout
.:53
2019-11-30T10:15:05.293Z [INFO] plugin/reload: Running configuration MD5 = 68ad62e82bb7a01ce4a04dd06bd0bf2c
2019-11-30T10:15:05.294Z [INFO] CoreDNS-1.6.2
2019-11-30T10:15:05.294Z [INFO] linux/amd64, go1.12.8, 795a3eb
CoreDNS-1.6.2
linux/amd64, go1.12.8, 795a3eb
2019-12-15T06:25:11.969Z [ERROR] plugin/errors: 2 8690ff65-fea8-4c25-9376-7b2d633d2245.internal.k8s.ondigitalocean.com. A: read udp 10.244.0.148:48223->67.207.67.3:53: i/o timeout
2019-12-15T06:25:11.928Z [ERROR] plugin/errors: 2 8690ff65-fea8-4c25-9376-7b2d633d2245.internal.k8s.ondigitalocean.com. AAAA: read udp 10.244.0.148:40733->67.207.67.3:53: i/o timeout
2019-12-15T06:25:17.475Z [ERROR] plugin/errors: 2 sgp1.sonar.digitalocean.com. A: read udp 10.244.0.148:44810->67.207.67.2:53: i/o timeout
2019-12-15T06:25:17.475Z [ERROR] plugin/errors: 2 sgp1.sonar.digitalocean.com. AAAA: read udp 10.244.0.148:33077->67.207.67.2:53: i/o timeout

and kube-dns service is following.

$ kubectl get svc --namespace=kube-system
NAME            TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                  AGE
kube-dns        ClusterIP   10.245.0.10     <none>        53/UDP,53/TCP,9153/TCP   20d

$ kubectl get ep kube-dns --namespace=kube-system
NAME       ENDPOINTS   AGE
kube-dns               20d

$ kubectl describe ep kube-dns --namespace=kube-system
Name:         kube-dns
Namespace:    kube-system
Labels:       k8s-app=kube-dns
              kubernetes.io/cluster-service=true
              kubernetes.io/name=CoreDNS
Annotations:  <none>
Subsets:
  Addresses:          <none>
  NotReadyAddresses:  10.244.0.114,10.244.0.148
  Ports:
    Name     Port  Protocol
    ----     ----  --------
    dns      53    UDP
    dns-tcp  53    TCP
    metrics  9153  TCP

Events:  <none>

$ kubectl get po coredns-84c79f5fb4-k8crt --namespace=kube-system
NAME                       READY   STATUS    RESTARTS   AGE
coredns-84c79f5fb4-k8crt   1/1     Running   0          20d
$ kubectl describe po coredns-84c79f5fb4-k8crt --namespace=kube-system
Name:                 coredns-84c79f5fb4-k8crt
Namespace:            kube-system
Priority:             2000000000
Priority Class Name:  system-cluster-critical
Node:                 pool-d2o-6v7u/10.130.13.143
Start Time:           Sat, 30 Nov 2019 19:15:01 +0900
Labels:               k8s-app=kube-dns
                      pod-template-hash=84c79f5fb4
Annotations:          <none>
Status:               Running
IP:                   10.244.0.114
IPs:
  IP:           10.244.0.114
Controlled By:  ReplicaSet/coredns-84c79f5fb4
Containers:
  coredns:
    Container ID:  docker://173d34004f06db3df388f0e6c8b2d7f72ae4c4adff286e664c3a8b5bb24f8f8e
    Image:         docker.io/coredns/coredns:1.6.2
    Image ID:      docker-pullable://coredns/coredns@sha256:12eb885b8685b1b13a04ecf5c23bc809c2e57917252fd7b0be9e9c00644e8ee5
    Ports:         53/UDP, 53/TCP, 9153/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      -conf
      /etc/coredns/Corefile
    State:          Running
      Started:      Sat, 30 Nov 2019 19:15:03 +0900
    Ready:          True
    Restart Count:  0
    Limits:
      memory:  170Mi
    Requests:
      cpu:        100m
      memory:     70Mi
    Liveness:     http-get http://:8080/health delay=60s timeout=5s period=10s #success=1 #failure=5
    Readiness:    http-get http://:8181/ready delay=0s timeout=1s period=10s #success=1 #failure=3
    Environment:  <none>
    Mounts:
      /etc/coredns from config-volume (ro)
      /var/run/secrets/kubernetes.io/serviceaccount from coredns-token-82b8t (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  config-volume:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      coredns
    Optional:  false
  coredns-token-82b8t:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  coredns-token-82b8t
    Optional:    false
QoS Class:       Burstable
Node-Selectors:  beta.kubernetes.io/os=linux
Tolerations:     CriticalAddonsOnly
                 node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:          <none>