Coredns in CrashLoopBackOff (kubernetes 1.11)










2















I'm trying to install kubernetes on an Ubuntu 16.04 VM, followed instructions at https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/, using weave as my pod network add-on.



I'm seeing similar issue as coredns pods have CrashLoopBackOff or Error state, but I didn't see a solution there, and the versions I'm using are different:



kubeadm 1.11.4-00
kubectl 1.11.4-00
kubelet 1.11.4-00
kubernetes-cni 0.6.0-00
Docker version 1.13.1-cs8, build 91ca5f2
weave script 2.5.0
weave 2.5.0


I'm running behind a corporate firewall, so I set my proxy variables, then ran kubeadm init as follows:



# echo $http_proxy
http://135.28.13.11:8080
# echo $https_proxy
http://135.28.13.11:8080
# echo $no_proxy
127.0.0.1,135.21.27.139,135.0.0.0/8,10.96.0.0/12,10.32.0.0/12
# kubeadm init --pod-network-cidr=10.32.0.0/12 
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d 'n')" 
# kubectl taint nodes --all node-role.kubernetes.io/master-


Both coredns pods stay in CrashLoopBackOff



# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
default hostnames-674b556c4-2b5h2 1/1 Running 0 5h 10.32.0.6 mtpnjvzonap001 <none>
default hostnames-674b556c4-4bzdj 1/1 Running 0 5h 10.32.0.5 mtpnjvzonap001 <none>
default hostnames-674b556c4-64gx5 1/1 Running 0 5h 10.32.0.4 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-s7rvx 0/1 CrashLoopBackOff 18 1h 10.32.0.7 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-vxwgv 0/1 CrashLoopBackOff 80 6h 10.32.0.2 mtpnjvzonap001 <none>
kube-system etcd-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-apiserver-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-controller-manager-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-proxy-2c4tx 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-scheduler-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system weave-net-bpx22 2/2 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>


coredns pods have this entry in their log




E1114 20:59:13.848196 1 reflector.go:205]
github.com/coredns/coredns/plugin/kubernetes/controller.go:313: Failed
to list *v1.Service: Get
https://10.96.0.1:443/api/v1/services?limit=500&resourceVersion=0:
dial tcp 10.96.0.1:443: i/o timeout




This suggests to me that coredns cannot access apiserver pod using its cluster IP:



# kubectl describe svc/kubernetes
Name: kubernetes
Namespace: default
Labels: component=apiserver
 provider=kubernetes
Annotations: <none>
Selector: <none>
Type: ClusterIP
IP: 10.96.0.1
Port: https 443/TCP
TargetPort: 6443/TCP
Endpoints: 135.21.27.139:6443
Session Affinity: None
Events: <none>


I also went through the troubleshooting steps at https://kubernetes.io/docs/tasks/debug-application-cluster/troubleshooting/



  • I created a busybox pod for testing

  • I created the hostnames deployment successfully

  • I exposed the hostnames deployment successfully

  • From the busybox pod, I accessed the hostnames service by its cluster IP successfully

  • from the node, I accessed the hostnames service by its cluster IP successfully

So in short, I created the hostnames service which had a cluster IP in 10.96.0.0/12 space (as expected), and it works, but for some reason, pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:



# wget --no-check-certificate https://10.96.0.1/hello
--2018-11-14 21:44:25-- https://10.96.0.1/hello
Connecting to 10.96.0.1:443... connected.
WARNING: cannot verify 10.96.0.1's certificate, issued by ‘CN=kubernetes’:
 Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 403 Forbidden
2018-11-14 21:44:25 ERROR 403: Forbidden.


Some other things I checked, based on advice from others who reported a similar problem:



# sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 1
# sysctl net.bridge.bridge-nf-call-iptables
net.bridge.bridge-nf-call-iptables = 1
# iptables-save | egrep ':INPUT|:OUTPUT|:POSTROUTING|:FORWARD'
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [11:692]
:POSTROUTING ACCEPT [11:692]
:INPUT ACCEPT [1697:364811]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1652:363693]
# ls -l /usr/sbin/conntrack
-rwxr-xr-x 1 root root 65632 Jan 24 2016 /usr/sbin/conntrack
# systemctl status firewalld
● firewalld.service
 Loaded: not-found (Reason: No such file or directory)
 Active: inactive (dead)


I checked the log for kube-proxy, did not see any errors.
I also tried deleting coredns pods, apiserver pod; they are recreated (as expected), but the problem remains.



Here's a copy of the log from the weave container



# kubectl logs -n kube-system weave-net-bpx22 weave
DEBU: 2018/11/14 15:56:10.909921 [kube-peers] Checking peer "aa:53:be:75:71:f7" against list &
Peer not in list; removing persisted data
INFO: 2018/11/14 15:56:11.041807 Command line options: map[name:aa:53:be:75:71:f7 nickname:mtpnjvzonap001 ipalloc-init:consensus=1 ipalloc-range:10.32.0.0/12 db-prefix:/weavedb/weave-net docker-api: expect-npc:true host-root:/host http-addr:127.0.0.1:6784 metrics-addr:0.0.0.0:6782 conn-limit:100 datapath:datapath no-dns:true port:6783]
INFO: 2018/11/14 15:56:11.042230 weave 2.5.0
INFO: 2018/11/14 15:56:11.198348 Bridge type is bridged_fastdp
INFO: 2018/11/14 15:56:11.198372 Communication between peers is unencrypted.
INFO: 2018/11/14 15:56:11.203206 Our name is aa:53:be:75:71:f7(mtpnjvzonap001)
INFO: 2018/11/14 15:56:11.203249 Launch detected - using supplied peer list: [135.21.27.139]
INFO: 2018/11/14 15:56:11.216398 Checking for pre-existing addresses on weave bridge
INFO: 2018/11/14 15:56:11.229313 [allocator aa:53:be:75:71:f7] No valid persisted data
INFO: 2018/11/14 15:56:11.233391 [allocator aa:53:be:75:71:f7] Initialising via deferred consensus
INFO: 2018/11/14 15:56:11.233443 Sniffing traffic on datapath (via ODP)
INFO: 2018/11/14 15:56:11.234120 ->[135.21.27.139:6783] attempting connection
INFO: 2018/11/14 15:56:11.234302 ->[135.21.27.139:49182] connection accepted
INFO: 2018/11/14 15:56:11.234818 ->[135.21.27.139:6783|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.234843 ->[135.21.27.139:49182|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.236010 Listening for HTTP control messages on 127.0.0.1:6784
INFO: 2018/11/14 15:56:11.236424 Listening for metrics requests on 0.0.0.0:6782
INFO: 2018/11/14 15:56:11.990529 [kube-peers] Added myself to peer list &[aa:53:be:75:71:f7 mtpnjvzonap001]
DEBU: 2018/11/14 15:56:11.995901 [kube-peers] Nodes that have disappeared: map
10.32.0.1
135.21.27.139
DEBU: 2018/11/14 15:56:12.075738 registering for updates for node delete events
INFO: 2018/11/14 15:56:41.279799 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/14 20:52:47.025412 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 01:46:32.842792 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 09:06:03.624359 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout
INFO: 2018/11/15 14:34:02.070893 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout


Here are the events for the 2 coredns pods



# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-6f9q6
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
41m 20h 245 coredns-78fcdf6894-6f9q6.1568eab25f0acb02 Pod spec.containerscoredns Normal Killing kubelet, mtpnjvzonap001 Killing container with id docker://coredns:Container failed liveness probe.. Container will be killed and recreated.
26m 20h 248 coredns-78fcdf6894-6f9q6.1568ea920f72ddd4 Pod spec.containerscoredns Normal Pulled kubelet, mtpnjvzonap001 Container image "k8s.gcr.io/coredns:1.1.3" already present on machine
5m 20h 1256 coredns-78fcdf6894-6f9q6.1568eaa1fd9216d2 Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2963 coredns-78fcdf6894-6f9q6.1568eb75f2b1af3e Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-skjwz
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
6m 20h 1259 coredns-78fcdf6894-skjwz.1568eaa181fbeffe Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2969 coredns-78fcdf6894-skjwz.1568eb7578188f24 Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
#


Any help or further troubleshooting steps are welcome






kubernetes kubeadm







share|improve this question
























  • Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

    – Matthew L Daniel
    Nov 15 '18 at 6:24











  • @jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

    – mk_sta
    Nov 15 '18 at 11:35












  • @MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

    – jm9816
    Nov 15 '18 at 17:07







  • 1





    Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

    – Kitt Hsu
    Nov 16 '18 at 6:58











  • @KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

    – jm9816
    Nov 16 '18 at 19:35
















2















I'm trying to install kubernetes on an Ubuntu 16.04 VM, followed instructions at https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/, using weave as my pod network add-on.



I'm seeing similar issue as coredns pods have CrashLoopBackOff or Error state, but I didn't see a solution there, and the versions I'm using are different:



kubeadm 1.11.4-00
kubectl 1.11.4-00
kubelet 1.11.4-00
kubernetes-cni 0.6.0-00
Docker version 1.13.1-cs8, build 91ca5f2
weave script 2.5.0
weave 2.5.0


I'm running behind a corporate firewall, so I set my proxy variables, then ran kubeadm init as follows:



# echo $http_proxy
http://135.28.13.11:8080
# echo $https_proxy
http://135.28.13.11:8080
# echo $no_proxy
127.0.0.1,135.21.27.139,135.0.0.0/8,10.96.0.0/12,10.32.0.0/12
# kubeadm init --pod-network-cidr=10.32.0.0/12 
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d 'n')" 
# kubectl taint nodes --all node-role.kubernetes.io/master-


Both coredns pods stay in CrashLoopBackOff



# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
default hostnames-674b556c4-2b5h2 1/1 Running 0 5h 10.32.0.6 mtpnjvzonap001 <none>
default hostnames-674b556c4-4bzdj 1/1 Running 0 5h 10.32.0.5 mtpnjvzonap001 <none>
default hostnames-674b556c4-64gx5 1/1 Running 0 5h 10.32.0.4 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-s7rvx 0/1 CrashLoopBackOff 18 1h 10.32.0.7 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-vxwgv 0/1 CrashLoopBackOff 80 6h 10.32.0.2 mtpnjvzonap001 <none>
kube-system etcd-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-apiserver-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-controller-manager-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-proxy-2c4tx 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-scheduler-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system weave-net-bpx22 2/2 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>


coredns pods have this entry in their log




E1114 20:59:13.848196 1 reflector.go:205]
github.com/coredns/coredns/plugin/kubernetes/controller.go:313: Failed
to list *v1.Service: Get
https://10.96.0.1:443/api/v1/services?limit=500&resourceVersion=0:
dial tcp 10.96.0.1:443: i/o timeout




This suggests to me that coredns cannot access apiserver pod using its cluster IP:



# kubectl describe svc/kubernetes
Name: kubernetes
Namespace: default
Labels: component=apiserver
 provider=kubernetes
Annotations: <none>
Selector: <none>
Type: ClusterIP
IP: 10.96.0.1
Port: https 443/TCP
TargetPort: 6443/TCP
Endpoints: 135.21.27.139:6443
Session Affinity: None
Events: <none>


I also went through the troubleshooting steps at https://kubernetes.io/docs/tasks/debug-application-cluster/troubleshooting/



  • I created a busybox pod for testing

  • I created the hostnames deployment successfully

  • I exposed the hostnames deployment successfully

  • From the busybox pod, I accessed the hostnames service by its cluster IP successfully

  • from the node, I accessed the hostnames service by its cluster IP successfully

So in short, I created the hostnames service which had a cluster IP in 10.96.0.0/12 space (as expected), and it works, but for some reason, pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:



# wget --no-check-certificate https://10.96.0.1/hello
--2018-11-14 21:44:25-- https://10.96.0.1/hello
Connecting to 10.96.0.1:443... connected.
WARNING: cannot verify 10.96.0.1's certificate, issued by ‘CN=kubernetes’:
 Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 403 Forbidden
2018-11-14 21:44:25 ERROR 403: Forbidden.


Some other things I checked, based on advice from others who reported a similar problem:



# sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 1
# sysctl net.bridge.bridge-nf-call-iptables
net.bridge.bridge-nf-call-iptables = 1
# iptables-save | egrep ':INPUT|:OUTPUT|:POSTROUTING|:FORWARD'
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [11:692]
:POSTROUTING ACCEPT [11:692]
:INPUT ACCEPT [1697:364811]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1652:363693]
# ls -l /usr/sbin/conntrack
-rwxr-xr-x 1 root root 65632 Jan 24 2016 /usr/sbin/conntrack
# systemctl status firewalld
● firewalld.service
 Loaded: not-found (Reason: No such file or directory)
 Active: inactive (dead)


I checked the log for kube-proxy, did not see any errors.
I also tried deleting coredns pods, apiserver pod; they are recreated (as expected), but the problem remains.



Here's a copy of the log from the weave container



# kubectl logs -n kube-system weave-net-bpx22 weave
DEBU: 2018/11/14 15:56:10.909921 [kube-peers] Checking peer "aa:53:be:75:71:f7" against list &
Peer not in list; removing persisted data
INFO: 2018/11/14 15:56:11.041807 Command line options: map[name:aa:53:be:75:71:f7 nickname:mtpnjvzonap001 ipalloc-init:consensus=1 ipalloc-range:10.32.0.0/12 db-prefix:/weavedb/weave-net docker-api: expect-npc:true host-root:/host http-addr:127.0.0.1:6784 metrics-addr:0.0.0.0:6782 conn-limit:100 datapath:datapath no-dns:true port:6783]
INFO: 2018/11/14 15:56:11.042230 weave 2.5.0
INFO: 2018/11/14 15:56:11.198348 Bridge type is bridged_fastdp
INFO: 2018/11/14 15:56:11.198372 Communication between peers is unencrypted.
INFO: 2018/11/14 15:56:11.203206 Our name is aa:53:be:75:71:f7(mtpnjvzonap001)
INFO: 2018/11/14 15:56:11.203249 Launch detected - using supplied peer list: [135.21.27.139]
INFO: 2018/11/14 15:56:11.216398 Checking for pre-existing addresses on weave bridge
INFO: 2018/11/14 15:56:11.229313 [allocator aa:53:be:75:71:f7] No valid persisted data
INFO: 2018/11/14 15:56:11.233391 [allocator aa:53:be:75:71:f7] Initialising via deferred consensus
INFO: 2018/11/14 15:56:11.233443 Sniffing traffic on datapath (via ODP)
INFO: 2018/11/14 15:56:11.234120 ->[135.21.27.139:6783] attempting connection
INFO: 2018/11/14 15:56:11.234302 ->[135.21.27.139:49182] connection accepted
INFO: 2018/11/14 15:56:11.234818 ->[135.21.27.139:6783|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.234843 ->[135.21.27.139:49182|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.236010 Listening for HTTP control messages on 127.0.0.1:6784
INFO: 2018/11/14 15:56:11.236424 Listening for metrics requests on 0.0.0.0:6782
INFO: 2018/11/14 15:56:11.990529 [kube-peers] Added myself to peer list &[aa:53:be:75:71:f7 mtpnjvzonap001]
DEBU: 2018/11/14 15:56:11.995901 [kube-peers] Nodes that have disappeared: map
10.32.0.1
135.21.27.139
DEBU: 2018/11/14 15:56:12.075738 registering for updates for node delete events
INFO: 2018/11/14 15:56:41.279799 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/14 20:52:47.025412 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 01:46:32.842792 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 09:06:03.624359 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout
INFO: 2018/11/15 14:34:02.070893 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout


Here are the events for the 2 coredns pods



# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-6f9q6
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
41m 20h 245 coredns-78fcdf6894-6f9q6.1568eab25f0acb02 Pod spec.containerscoredns Normal Killing kubelet, mtpnjvzonap001 Killing container with id docker://coredns:Container failed liveness probe.. Container will be killed and recreated.
26m 20h 248 coredns-78fcdf6894-6f9q6.1568ea920f72ddd4 Pod spec.containerscoredns Normal Pulled kubelet, mtpnjvzonap001 Container image "k8s.gcr.io/coredns:1.1.3" already present on machine
5m 20h 1256 coredns-78fcdf6894-6f9q6.1568eaa1fd9216d2 Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2963 coredns-78fcdf6894-6f9q6.1568eb75f2b1af3e Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-skjwz
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
6m 20h 1259 coredns-78fcdf6894-skjwz.1568eaa181fbeffe Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2969 coredns-78fcdf6894-skjwz.1568eb7578188f24 Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
#


Any help or further troubleshooting steps are welcome






kubernetes kubeadm







share|improve this question
























  • Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

    – Matthew L Daniel
    Nov 15 '18 at 6:24











  • @jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

    – mk_sta
    Nov 15 '18 at 11:35












  • @MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

    – jm9816
    Nov 15 '18 at 17:07







  • 1





    Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

    – Kitt Hsu
    Nov 16 '18 at 6:58











  • @KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

    – jm9816
    Nov 16 '18 at 19:35














2












2








2








I'm trying to install kubernetes on an Ubuntu 16.04 VM, followed instructions at https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/, using weave as my pod network add-on.



I'm seeing similar issue as coredns pods have CrashLoopBackOff or Error state, but I didn't see a solution there, and the versions I'm using are different:



kubeadm 1.11.4-00
kubectl 1.11.4-00
kubelet 1.11.4-00
kubernetes-cni 0.6.0-00
Docker version 1.13.1-cs8, build 91ca5f2
weave script 2.5.0
weave 2.5.0


I'm running behind a corporate firewall, so I set my proxy variables, then ran kubeadm init as follows:



# echo $http_proxy
http://135.28.13.11:8080
# echo $https_proxy
http://135.28.13.11:8080
# echo $no_proxy
127.0.0.1,135.21.27.139,135.0.0.0/8,10.96.0.0/12,10.32.0.0/12
# kubeadm init --pod-network-cidr=10.32.0.0/12 
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d 'n')" 
# kubectl taint nodes --all node-role.kubernetes.io/master-


Both coredns pods stay in CrashLoopBackOff



# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
default hostnames-674b556c4-2b5h2 1/1 Running 0 5h 10.32.0.6 mtpnjvzonap001 <none>
default hostnames-674b556c4-4bzdj 1/1 Running 0 5h 10.32.0.5 mtpnjvzonap001 <none>
default hostnames-674b556c4-64gx5 1/1 Running 0 5h 10.32.0.4 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-s7rvx 0/1 CrashLoopBackOff 18 1h 10.32.0.7 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-vxwgv 0/1 CrashLoopBackOff 80 6h 10.32.0.2 mtpnjvzonap001 <none>
kube-system etcd-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-apiserver-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-controller-manager-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-proxy-2c4tx 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-scheduler-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system weave-net-bpx22 2/2 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>


coredns pods have this entry in their log




E1114 20:59:13.848196 1 reflector.go:205]
github.com/coredns/coredns/plugin/kubernetes/controller.go:313: Failed
to list *v1.Service: Get
https://10.96.0.1:443/api/v1/services?limit=500&resourceVersion=0:
dial tcp 10.96.0.1:443: i/o timeout




This suggests to me that coredns cannot access apiserver pod using its cluster IP:



# kubectl describe svc/kubernetes
Name: kubernetes
Namespace: default
Labels: component=apiserver
 provider=kubernetes
Annotations: <none>
Selector: <none>
Type: ClusterIP
IP: 10.96.0.1
Port: https 443/TCP
TargetPort: 6443/TCP
Endpoints: 135.21.27.139:6443
Session Affinity: None
Events: <none>


I also went through the troubleshooting steps at https://kubernetes.io/docs/tasks/debug-application-cluster/troubleshooting/



  • I created a busybox pod for testing

  • I created the hostnames deployment successfully

  • I exposed the hostnames deployment successfully

  • From the busybox pod, I accessed the hostnames service by its cluster IP successfully

  • from the node, I accessed the hostnames service by its cluster IP successfully

So in short, I created the hostnames service which had a cluster IP in 10.96.0.0/12 space (as expected), and it works, but for some reason, pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:



# wget --no-check-certificate https://10.96.0.1/hello
--2018-11-14 21:44:25-- https://10.96.0.1/hello
Connecting to 10.96.0.1:443... connected.
WARNING: cannot verify 10.96.0.1's certificate, issued by ‘CN=kubernetes’:
 Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 403 Forbidden
2018-11-14 21:44:25 ERROR 403: Forbidden.


Some other things I checked, based on advice from others who reported a similar problem:



# sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 1
# sysctl net.bridge.bridge-nf-call-iptables
net.bridge.bridge-nf-call-iptables = 1
# iptables-save | egrep ':INPUT|:OUTPUT|:POSTROUTING|:FORWARD'
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [11:692]
:POSTROUTING ACCEPT [11:692]
:INPUT ACCEPT [1697:364811]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1652:363693]
# ls -l /usr/sbin/conntrack
-rwxr-xr-x 1 root root 65632 Jan 24 2016 /usr/sbin/conntrack
# systemctl status firewalld
● firewalld.service
 Loaded: not-found (Reason: No such file or directory)
 Active: inactive (dead)


I checked the log for kube-proxy, did not see any errors.
I also tried deleting coredns pods, apiserver pod; they are recreated (as expected), but the problem remains.



Here's a copy of the log from the weave container



# kubectl logs -n kube-system weave-net-bpx22 weave
DEBU: 2018/11/14 15:56:10.909921 [kube-peers] Checking peer "aa:53:be:75:71:f7" against list &
Peer not in list; removing persisted data
INFO: 2018/11/14 15:56:11.041807 Command line options: map[name:aa:53:be:75:71:f7 nickname:mtpnjvzonap001 ipalloc-init:consensus=1 ipalloc-range:10.32.0.0/12 db-prefix:/weavedb/weave-net docker-api: expect-npc:true host-root:/host http-addr:127.0.0.1:6784 metrics-addr:0.0.0.0:6782 conn-limit:100 datapath:datapath no-dns:true port:6783]
INFO: 2018/11/14 15:56:11.042230 weave 2.5.0
INFO: 2018/11/14 15:56:11.198348 Bridge type is bridged_fastdp
INFO: 2018/11/14 15:56:11.198372 Communication between peers is unencrypted.
INFO: 2018/11/14 15:56:11.203206 Our name is aa:53:be:75:71:f7(mtpnjvzonap001)
INFO: 2018/11/14 15:56:11.203249 Launch detected - using supplied peer list: [135.21.27.139]
INFO: 2018/11/14 15:56:11.216398 Checking for pre-existing addresses on weave bridge
INFO: 2018/11/14 15:56:11.229313 [allocator aa:53:be:75:71:f7] No valid persisted data
INFO: 2018/11/14 15:56:11.233391 [allocator aa:53:be:75:71:f7] Initialising via deferred consensus
INFO: 2018/11/14 15:56:11.233443 Sniffing traffic on datapath (via ODP)
INFO: 2018/11/14 15:56:11.234120 ->[135.21.27.139:6783] attempting connection
INFO: 2018/11/14 15:56:11.234302 ->[135.21.27.139:49182] connection accepted
INFO: 2018/11/14 15:56:11.234818 ->[135.21.27.139:6783|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.234843 ->[135.21.27.139:49182|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.236010 Listening for HTTP control messages on 127.0.0.1:6784
INFO: 2018/11/14 15:56:11.236424 Listening for metrics requests on 0.0.0.0:6782
INFO: 2018/11/14 15:56:11.990529 [kube-peers] Added myself to peer list &[aa:53:be:75:71:f7 mtpnjvzonap001]
DEBU: 2018/11/14 15:56:11.995901 [kube-peers] Nodes that have disappeared: map
10.32.0.1
135.21.27.139
DEBU: 2018/11/14 15:56:12.075738 registering for updates for node delete events
INFO: 2018/11/14 15:56:41.279799 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/14 20:52:47.025412 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 01:46:32.842792 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 09:06:03.624359 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout
INFO: 2018/11/15 14:34:02.070893 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout


Here are the events for the 2 coredns pods



# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-6f9q6
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
41m 20h 245 coredns-78fcdf6894-6f9q6.1568eab25f0acb02 Pod spec.containerscoredns Normal Killing kubelet, mtpnjvzonap001 Killing container with id docker://coredns:Container failed liveness probe.. Container will be killed and recreated.
26m 20h 248 coredns-78fcdf6894-6f9q6.1568ea920f72ddd4 Pod spec.containerscoredns Normal Pulled kubelet, mtpnjvzonap001 Container image "k8s.gcr.io/coredns:1.1.3" already present on machine
5m 20h 1256 coredns-78fcdf6894-6f9q6.1568eaa1fd9216d2 Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2963 coredns-78fcdf6894-6f9q6.1568eb75f2b1af3e Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-skjwz
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
6m 20h 1259 coredns-78fcdf6894-skjwz.1568eaa181fbeffe Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2969 coredns-78fcdf6894-skjwz.1568eb7578188f24 Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
#


Any help or further troubleshooting steps are welcome






kubernetes kubeadm







share|improve this question
















I'm trying to install kubernetes on an Ubuntu 16.04 VM, followed instructions at https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/, using weave as my pod network add-on.



I'm seeing similar issue as coredns pods have CrashLoopBackOff or Error state, but I didn't see a solution there, and the versions I'm using are different:



kubeadm 1.11.4-00
kubectl 1.11.4-00
kubelet 1.11.4-00
kubernetes-cni 0.6.0-00
Docker version 1.13.1-cs8, build 91ca5f2
weave script 2.5.0
weave 2.5.0


I'm running behind a corporate firewall, so I set my proxy variables, then ran kubeadm init as follows:



# echo $http_proxy
http://135.28.13.11:8080
# echo $https_proxy
http://135.28.13.11:8080
# echo $no_proxy
127.0.0.1,135.21.27.139,135.0.0.0/8,10.96.0.0/12,10.32.0.0/12
# kubeadm init --pod-network-cidr=10.32.0.0/12 
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d 'n')" 
# kubectl taint nodes --all node-role.kubernetes.io/master-


Both coredns pods stay in CrashLoopBackOff



# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
default hostnames-674b556c4-2b5h2 1/1 Running 0 5h 10.32.0.6 mtpnjvzonap001 <none>
default hostnames-674b556c4-4bzdj 1/1 Running 0 5h 10.32.0.5 mtpnjvzonap001 <none>
default hostnames-674b556c4-64gx5 1/1 Running 0 5h 10.32.0.4 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-s7rvx 0/1 CrashLoopBackOff 18 1h 10.32.0.7 mtpnjvzonap001 <none>
kube-system coredns-78fcdf6894-vxwgv 0/1 CrashLoopBackOff 80 6h 10.32.0.2 mtpnjvzonap001 <none>
kube-system etcd-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-apiserver-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-controller-manager-mtpnjvzonap001 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-proxy-2c4tx 1/1 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>
kube-system kube-scheduler-mtpnjvzonap001 1/1 Running 0 1h 135.21.27.139 mtpnjvzonap001 <none>
kube-system weave-net-bpx22 2/2 Running 0 6h 135.21.27.139 mtpnjvzonap001 <none>


coredns pods have this entry in their log




E1114 20:59:13.848196 1 reflector.go:205]
github.com/coredns/coredns/plugin/kubernetes/controller.go:313: Failed
to list *v1.Service: Get
https://10.96.0.1:443/api/v1/services?limit=500&resourceVersion=0:
dial tcp 10.96.0.1:443: i/o timeout




This suggests to me that coredns cannot access apiserver pod using its cluster IP:



# kubectl describe svc/kubernetes
Name: kubernetes
Namespace: default
Labels: component=apiserver
 provider=kubernetes
Annotations: <none>
Selector: <none>
Type: ClusterIP
IP: 10.96.0.1
Port: https 443/TCP
TargetPort: 6443/TCP
Endpoints: 135.21.27.139:6443
Session Affinity: None
Events: <none>


I also went through the troubleshooting steps at https://kubernetes.io/docs/tasks/debug-application-cluster/troubleshooting/



  • I created a busybox pod for testing

  • I created the hostnames deployment successfully

  • I exposed the hostnames deployment successfully

  • From the busybox pod, I accessed the hostnames service by its cluster IP successfully

  • from the node, I accessed the hostnames service by its cluster IP successfully

So in short, I created the hostnames service which had a cluster IP in 10.96.0.0/12 space (as expected), and it works, but for some reason, pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:



# wget --no-check-certificate https://10.96.0.1/hello
--2018-11-14 21:44:25-- https://10.96.0.1/hello
Connecting to 10.96.0.1:443... connected.
WARNING: cannot verify 10.96.0.1's certificate, issued by ‘CN=kubernetes’:
 Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 403 Forbidden
2018-11-14 21:44:25 ERROR 403: Forbidden.


Some other things I checked, based on advice from others who reported a similar problem:



# sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 1
# sysctl net.bridge.bridge-nf-call-iptables
net.bridge.bridge-nf-call-iptables = 1
# iptables-save | egrep ':INPUT|:OUTPUT|:POSTROUTING|:FORWARD'
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [11:692]
:POSTROUTING ACCEPT [11:692]
:INPUT ACCEPT [1697:364811]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1652:363693]
# ls -l /usr/sbin/conntrack
-rwxr-xr-x 1 root root 65632 Jan 24 2016 /usr/sbin/conntrack
# systemctl status firewalld
● firewalld.service
 Loaded: not-found (Reason: No such file or directory)
 Active: inactive (dead)


I checked the log for kube-proxy, did not see any errors.
I also tried deleting coredns pods, apiserver pod; they are recreated (as expected), but the problem remains.



Here's a copy of the log from the weave container



# kubectl logs -n kube-system weave-net-bpx22 weave
DEBU: 2018/11/14 15:56:10.909921 [kube-peers] Checking peer "aa:53:be:75:71:f7" against list &
Peer not in list; removing persisted data
INFO: 2018/11/14 15:56:11.041807 Command line options: map[name:aa:53:be:75:71:f7 nickname:mtpnjvzonap001 ipalloc-init:consensus=1 ipalloc-range:10.32.0.0/12 db-prefix:/weavedb/weave-net docker-api: expect-npc:true host-root:/host http-addr:127.0.0.1:6784 metrics-addr:0.0.0.0:6782 conn-limit:100 datapath:datapath no-dns:true port:6783]
INFO: 2018/11/14 15:56:11.042230 weave 2.5.0
INFO: 2018/11/14 15:56:11.198348 Bridge type is bridged_fastdp
INFO: 2018/11/14 15:56:11.198372 Communication between peers is unencrypted.
INFO: 2018/11/14 15:56:11.203206 Our name is aa:53:be:75:71:f7(mtpnjvzonap001)
INFO: 2018/11/14 15:56:11.203249 Launch detected - using supplied peer list: [135.21.27.139]
INFO: 2018/11/14 15:56:11.216398 Checking for pre-existing addresses on weave bridge
INFO: 2018/11/14 15:56:11.229313 [allocator aa:53:be:75:71:f7] No valid persisted data
INFO: 2018/11/14 15:56:11.233391 [allocator aa:53:be:75:71:f7] Initialising via deferred consensus
INFO: 2018/11/14 15:56:11.233443 Sniffing traffic on datapath (via ODP)
INFO: 2018/11/14 15:56:11.234120 ->[135.21.27.139:6783] attempting connection
INFO: 2018/11/14 15:56:11.234302 ->[135.21.27.139:49182] connection accepted
INFO: 2018/11/14 15:56:11.234818 ->[135.21.27.139:6783|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.234843 ->[135.21.27.139:49182|aa:53:be:75:71:f7(mtpnjvzonap001)]: connection shutting down due to error: cannot connect to ourself
INFO: 2018/11/14 15:56:11.236010 Listening for HTTP control messages on 127.0.0.1:6784
INFO: 2018/11/14 15:56:11.236424 Listening for metrics requests on 0.0.0.0:6782
INFO: 2018/11/14 15:56:11.990529 [kube-peers] Added myself to peer list &[aa:53:be:75:71:f7 mtpnjvzonap001]
DEBU: 2018/11/14 15:56:11.995901 [kube-peers] Nodes that have disappeared: map
10.32.0.1
135.21.27.139
DEBU: 2018/11/14 15:56:12.075738 registering for updates for node delete events
INFO: 2018/11/14 15:56:41.279799 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/14 20:52:47.025412 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 01:46:32.842792 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 74.125.196.121:443: i/o timeout
INFO: 2018/11/15 09:06:03.624359 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout
INFO: 2018/11/15 14:34:02.070893 Error checking version: Get https://checkpoint-api.weave.works/v1/check/weave-net?arch=amd64&flag_docker-version=none&flag_kernel-version=4.4.0-135-generic&flag_kubernetes-cluster-size=1&flag_kubernetes-cluster-uid=ce66cb23-e825-11e8-abc3-525400314503&flag_kubernetes-version=v1.11.4&os=linux&signature=EJdydeNysrC7LC5xAJAKyDvxXCvkeWUFzepdk3QDfr0%3D&version=2.5.0: dial tcp 172.217.9.147:443: i/o timeout


Here are the events for the 2 coredns pods



# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-6f9q6
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
41m 20h 245 coredns-78fcdf6894-6f9q6.1568eab25f0acb02 Pod spec.containerscoredns Normal Killing kubelet, mtpnjvzonap001 Killing container with id docker://coredns:Container failed liveness probe.. Container will be killed and recreated.
26m 20h 248 coredns-78fcdf6894-6f9q6.1568ea920f72ddd4 Pod spec.containerscoredns Normal Pulled kubelet, mtpnjvzonap001 Container image "k8s.gcr.io/coredns:1.1.3" already present on machine
5m 20h 1256 coredns-78fcdf6894-6f9q6.1568eaa1fd9216d2 Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2963 coredns-78fcdf6894-6f9q6.1568eb75f2b1af3e Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
# kubectl get events -n kube-system --field-selector involvedObject.name=coredns-78fcdf6894-skjwz
LAST SEEN FIRST SEEN COUNT NAME KIND SUBOBJECT TYPE REASON SOURCE MESSAGE
6m 20h 1259 coredns-78fcdf6894-skjwz.1568eaa181fbeffe Pod spec.containerscoredns Warning Unhealthy kubelet, mtpnjvzonap001 Liveness probe failed: HTTP probe failed with statuscode: 503
1m 19h 2969 coredns-78fcdf6894-skjwz.1568eb7578188f24 Pod spec.containerscoredns Warning BackOff kubelet, mtpnjvzonap001 Back-off restarting failed container
#


Any help or further troubleshooting steps are welcome






kubernetes kubeadm




kubernetes kubeadm






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edited Nov 21 '18 at 15:21







jm9816

















asked Nov 14 '18 at 22:27









jm9816jm9816

112




112












  • Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

    – Matthew L Daniel
    Nov 15 '18 at 6:24











  • @jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

    – mk_sta
    Nov 15 '18 at 11:35












  • @MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

    – jm9816
    Nov 15 '18 at 17:07







  • 1





    Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

    – Kitt Hsu
    Nov 16 '18 at 6:58











  • @KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

    – jm9816
    Nov 16 '18 at 19:35


















  • Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

    – Matthew L Daniel
    Nov 15 '18 at 6:24











  • @jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

    – mk_sta
    Nov 15 '18 at 11:35












  • @MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

    – jm9816
    Nov 15 '18 at 17:07







  • 1





    Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

    – Kitt Hsu
    Nov 16 '18 at 6:58











  • @KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

    – jm9816
    Nov 16 '18 at 19:35

















Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

– Matthew L Daniel
Nov 15 '18 at 6:24





Hi jm9816, welcome to SO! I suspect that "pods cannot access the apiserver's cluster IP of 10.96.0.1, though from the node I can access 10.96.0.1:" is due to CNI failure. You might want to check your kubectl logs weave-net-bpx22 and see if weave failed to initialize. And in all circumstances, you'll want to check the situation on a Node, and not the master. Good luck!

– Matthew L Daniel
Nov 15 '18 at 6:24













@jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

– mk_sta
Nov 15 '18 at 11:35






@jm9816, issue probably connected with CNI as @Matthew L Daniel mentioned. Are you discovering any suspicious events in weave pod? kubectl logs weave-net-bpx22 -n kube-system -c weave; kubectl logs weave-net-bpx22 -n kube-system -c weave-npc

– mk_sta
Nov 15 '18 at 11:35














@MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

– jm9816
Nov 15 '18 at 17:07






@MatthewLDaniel - thanks for the suggestions. I should mention I have a single node cluster. But that shouldn't trigger a problem with coredns, right? About weave: I updated my entry to include the weave container log, if that is of interest. I actually opened an issue with weave, but did not get a resolution. So I decided to try it with flannel. I ran kubeadm reset, rebooted my vm for good measure, then re-ran kubeadm init, ... kubectl apply .. this time, using flannel. Result was the same, coredns in CrashLoopBackOff with same error message.

– jm9816
Nov 15 '18 at 17:07





1




1





Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

– Kitt Hsu
Nov 16 '18 at 6:58





Hi, you can try iptables -P FORWARD ACCEPT to bypass the WeaveNet NPC temporarily.

– Kitt Hsu
Nov 16 '18 at 6:58













@KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

– jm9816
Nov 16 '18 at 19:35






@KittHsu thanks, already have that in place # iptables-save | fgrep ':FORWARD' :FORWARD ACCEPT [0:0]

– jm9816
Nov 16 '18 at 19:35













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