My solution was to delete --network-plugin=cni in /var/lib/kubelet/kubeadmflags.env then restart the machine, the COredns will be running. Good luck

I also have the same issue.

I've solved the problem by deleting the plugins 'loop' within the cm of coredns. but i don't know if this cloud case other porblems.

1、kubectl edit cm coredns -n kube-system

2、delete ‘loop’ ,save and exit

3、restart coredns pods by：kubectl delete pod coredns.... -n kube-system

Somewhat resolved by using this way:

1. open and edit the configmap of coredns.

   kubectl edit cm coredns -n kube-system

2. "replacing proxy . /etc/resolv.conf with the ip address of your upstream DNS, for example proxy . 8.8.8.8." According to the link in the output of the coredns log (at the end of the page)

3. save and exit.

4. kubectl get pods -n kube-system -oname |grep coredns |xargs kubectl delete -n kube-system

The reason of the problem is explained in the link. You can find this link in the output of this cmd

kubectl logs coredns-7d9cd4f75b-cpwxp -n kube-system

This link is in the output of the CoreDNS-1.2.4.

I upgrade the CoreDNS using this cmd

kubectl patch deployment -n=kube-system coredns -p '{"spec": {"template": {"spec":{"containers":[{"image":"k8s.gcr.io/coredns:1.2.4", "name":"coredns","resources":{"limits":{"memory":"1Gi"},"requests":{"cpu":"100m","memory":"70Mi"}}}]}}}}'

My solution was to delete --network-plugin=cni in /var/lib/kubelet/kubeadm-flags.env

Yes, you are right. The issue was described here and on GitHub. And the resolution is to upgrade Docker, disable SElinux or modify allowPrivilegeEscalation to true. However, today I have tried to reproduce your issue and wasn't able to do this. Providing you commands and output, maybe it will help you create a working version from the beginning.

Docker version 17.03.2-ce, Kubernetes v1.12.0, Ubuntu 16.04, CoreDNS-1.2.2, instance created in GCP.

#apt-get update && apt-get install -y mc ebtables ethtool docker.io apt-transport-https curl
#curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -

#cat <<EOF >/etc/apt/sources.list.d/kubernetes.list \
deb http://apt.kubernetes.io/ kubernetes-xenial main \
EOF

#apt-get update && apt-get install -y kubelet kubeadm kubectl

#kubeadm init
$mkdir -p $HOME/.kube
$sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$sudo chown $(id -u):$(id -g) $HOME/.kube/config
$kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

serviceaccount/weave-net created

clusterrole.rbac.authorization.k8s.io/weave-net created

clusterrolebinding.rbac.authorization.k8s.io/weave-net created

role.rbac.authorization.k8s.io/weave-net created

rolebinding.rbac.authorization.k8s.io/weave-net created

daemonset.extensions/weave-net created

$kubectl get pods --all-namespaces
NAMESPACE     NAME                                              READY   STATUS              RESTARTS   AGE
kube-system   pod/coredns-576cbf47c7-6qbtq                      0/1     Pending             0          79s
kube-system   pod/coredns-576cbf47c7-jr6hb                      0/1     Pending             0          79s
kube-system   pod/etcd-kube-weave-master-1                      1/1     Running             0          38s
kube-system   pod/kube-apiserver-kube-weave-master-1            1/1     Running             0          28s
kube-system   pod/kube-controller-manager-kube-weave-master-1   1/1     Running             0          30s
kube-system   pod/kube-proxy-4p9l5                              1/1     Running             0          79s
kube-system   pod/kube-scheduler-kube-weave-master-1            1/1     Running             0          34s
kube-system   pod/weave-net-z6mhw                               0/2     ContainerCreating   0          8s

And again in a minute:

$kubectl get pods --all-namespaces
NAMESPACE     NAME                                              READY   STATUS    RESTARTS   AGE
kube-system   pod/coredns-576cbf47c7-6qbtq                      1/1     Running   0          98s
kube-system   pod/coredns-576cbf47c7-jr6hb                      1/1     Running   0          98s
kube-system   pod/etcd-kube-weave-master-1                      1/1     Running   0          57s
kube-system   pod/kube-apiserver-kube-weave-master-1            1/1     Running   0          47s
kube-system   pod/kube-controller-manager-kube-weave-master-1   1/1     Running   0          49s
kube-system   pod/kube-proxy-4p9l5                              1/1     Running   0          98s
kube-system   pod/kube-scheduler-kube-weave-master-1            1/1     Running   0          53s
kube-system   pod/weave-net-z6mhw                               2/2     Running   0          27s

Coredns pod description:

kubectl describe pod/coredns-576cbf47c7-6qbtq -n kube-system
Name:               coredns-576cbf47c7-6qbtq
Namespace:          kube-system
Priority:           0
PriorityClassName:  <none>
Node:               kube-weave-master-1/10.154.0.8
Start Time:         Fri, 05 Oct 2018 11:06:54 +0000
Labels:             k8s-app=kube-dns
                    pod-template-hash=576cbf47c7
Annotations:        <none>
Status:             Running
IP:                 10.32.0.3
Controlled By:      ReplicaSet/coredns-576cbf47c7
Containers:
  coredns:
    Container ID:  docker://db1712600b4c927b99063fa41bc36c3346c55572bd63730fc993f03379fa457b
    Image:         k8s.gcr.io/coredns:1.2.2
    Image ID:      docker-pullable://k8s.gcr.io/coredns@sha256:3e2be1cec87aca0b74b7668bbe8c02964a95a402e45ceb51b2252629d608d03a
    Ports:         53/UDP, 53/TCP, 9153/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      -conf
      /etc/coredns/Corefile
    State:          Running
      Started:      Fri, 05 Oct 2018 11:06:57 +0000
    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
    Environment:  <none>
    Mounts:
      /etc/coredns from config-volume (ro)
      /var/run/secrets/kubernetes.io/serviceaccount from coredns-token-wp7tm (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  config-volume:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      coredns
    Optional:  false
  coredns-token-wp7tm:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  coredns-token-wp7tm
    Optional:    false
QoS Class:       Burstable
Node-Selectors:  <none>
Tolerations:     CriticalAddonsOnly
                 node-role.kubernetes.io/master:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason            Age                 From                          Message
  ----     ------            ----                ----                          -------
  Warning  FailedScheduling  23m (x12 over 24m)  default-scheduler             0/1 nodes are available: 1 node(s) had taints that the pod didn't tolerate.
  Normal   Scheduled         23m                 default-scheduler             Successfully assigned kube-system/coredns-576cbf47c7-6qbtq to kube-weave-master-1
  Normal   Pulled            23m                 kubelet, kube-weave-master-1  Container image "k8s.gcr.io/coredns:1.2.2" already present on machine
  Normal   Created           23m                 kubelet, kube-weave-master-1  Created container
  Normal   Started           23m                 kubelet, kube-weave-master-1  Started container

Also, provide your config.yaml that is used by kubeadm init --config config.yaml to better understand your problem with specifying config file location.

I think simply delete loop function from Kubernetes is not a clean approach. CoreDNS Github actually provides some guidelines for trouble shooting this issue.

They suggest in their guideline about 3 approaches

• Add the following to kubelet: --resolv-conf . Your "real" resolv.conf is the one that contains the actual IPs of your upstream servers, and no local/loopback address. This flag tells kubelet to pass an alternate resolv.conf to Pods. For systems using systemd-resolved, /run/systemd/resolve/resolv.conf is typically the location of the "real" resolv.conf, although this can be different depending on your distribution.
• Disable the local DNS cache on host nodes, and restore /etc/resolv.conf to the original.
• A quick and dirty fix is to edit your Corefile, replacing proxy . /etc/resolv.conf with the ip address of your upstream DNS, for example proxy . 8.8.8.8. But this only fixes the issue for CoreDNS, kubelet will continue to forward the invalid resolv.conf to all default dnsPolicy Pods, leaving them unable to resolve DNS.