kube-dns keeps restarting with kubenetes on coreos - kubernetes

Question

I have Kubernetes installed on Container Linux by CoreOS alpha (1353.1.0)
using hyperkube v1.5.5_coreos.0 using my fork of coreos-kubernetes install scripts at https://github.com/kfirufk/coreos-kubernetes.
I have two ContainerOS machines.
coreos-2.tux-in.com resolved as 192.168.1.2 as controller
coreos-3.tux-in.com resolved as 192.168.1.3 as worker
kubectl get pods --all-namespaces returns
NAMESPACE NAME READY STATUS RESTARTS AGE
ceph ceph-mds-2743106415-rkww4 0/1 Pending 0 1d
ceph ceph-mon-check-3856521781-bd6k5 1/1 Running 0 1d
kube-lego kube-lego-3323932148-g2tf4 1/1 Running 0 1d
kube-system calico-node-xq6j7 2/2 Running 0 1d
kube-system calico-node-xzpp2 2/2 Running 4560 1d
kube-system calico-policy-controller-610849172-b7xjr 1/1 Running 0 1d
kube-system heapster-v1.3.0-beta.0-2754576759-v1f50 2/2 Running 0 1d
kube-system kube-apiserver-192.168.1.2 1/1 Running 0 1d
kube-system kube-controller-manager-192.168.1.2 1/1 Running 1 1d
kube-system kube-dns-3675956729-r7hhf 3/4 Running 3924 1d
kube-system kube-dns-autoscaler-505723555-l2pph 1/1 Running 0 1d
kube-system kube-proxy-192.168.1.2 1/1 Running 0 1d
kube-system kube-proxy-192.168.1.3 1/1 Running 0 1d
kube-system kube-scheduler-192.168.1.2 1/1 Running 1 1d
kube-system kubernetes-dashboard-3697905830-vdz23 1/1 Running 1246 1d
kube-system monitoring-grafana-4013973156-m2r2v 1/1 Running 0 1d
kube-system monitoring-influxdb-651061958-2mdtf 1/1 Running 0 1d
nginx-ingress default-http-backend-150165654-s4z04 1/1 Running 2 1d
so I can see that kube-dns-782804071-h78rf keeps restarting.
kubectl describe pod kube-dns-3675956729-r7hhf --namespace=kube-system returns:
Name: kube-dns-3675956729-r7hhf
Namespace: kube-system
Node: 192.168.1.2/192.168.1.2
Start Time: Sat, 11 Mar 2017 17:54:14 +0000
Labels: k8s-app=kube-dns
pod-template-hash=3675956729
Status: Running
IP: 10.2.67.243
Controllers: ReplicaSet/kube-dns-3675956729
Containers:
kubedns:
Container ID: rkt://f6480fe7-4316-4e0e-9483-0944feb85ea3:kubedns
Image: gcr.io/google_containers/kubedns-amd64:1.9
Image ID: rkt://sha512-c7b7c9c4393bea5f9dc5bcbe1acf1036c2aca36ac14b5e17fd3c675a396c4219
Ports: 10053/UDP, 10053/TCP, 10055/TCP
Args:
--domain=cluster.local.
--dns-port=10053
--config-map=kube-dns
--v=2
Limits:
memory: 170Mi
Requests:
cpu: 100m
memory: 70Mi
State: Running
Started: Sun, 12 Mar 2017 17:47:41 +0000
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Sun, 12 Mar 2017 17:46:28 +0000
Finished: Sun, 12 Mar 2017 17:47:02 +0000
Ready: False
Restart Count: 981
Liveness: http-get http://:8080/healthz-kubedns delay=60s timeout=5s period=10s #success=1 #failure=5
Readiness: http-get http://:8081/readiness delay=3s timeout=5s period=10s #success=1 #failure=3
Volume Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-zqbdp (ro)
Environment Variables:
PROMETHEUS_PORT: 10055
dnsmasq:
Container ID: rkt://f6480fe7-4316-4e0e-9483-0944feb85ea3:dnsmasq
Image: gcr.io/google_containers/kube-dnsmasq-amd64:1.4.1
Image ID: rkt://sha512-8c5f8b40f6813bb676ce04cd545c55add0dc8af5a3be642320244b74ea03f872
Ports: 53/UDP, 53/TCP
Args:
--cache-size=1000
--no-resolv
--server=127.0.0.1#10053
--log-facility=-
Requests:
cpu: 150m
memory: 10Mi
State: Running
Started: Sun, 12 Mar 2017 17:47:41 +0000
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Sun, 12 Mar 2017 17:46:28 +0000
Finished: Sun, 12 Mar 2017 17:47:02 +0000
Ready: True
Restart Count: 981
Liveness: http-get http://:8080/healthz-dnsmasq delay=60s timeout=5s period=10s #success=1 #failure=5
Volume Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-zqbdp (ro)
Environment Variables: <none>
dnsmasq-metrics:
Container ID: rkt://f6480fe7-4316-4e0e-9483-0944feb85ea3:dnsmasq-metrics
Image: gcr.io/google_containers/dnsmasq-metrics-amd64:1.0.1
Image ID: rkt://sha512-ceb3b6af1cd67389358be14af36b5e8fb6925e78ca137b28b93e0d8af134585b
Port: 10054/TCP
Args:
--v=2
--logtostderr
Requests:
memory: 10Mi
State: Running
Started: Sun, 12 Mar 2017 17:47:41 +0000
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Sun, 12 Mar 2017 17:46:28 +0000
Finished: Sun, 12 Mar 2017 17:47:02 +0000
Ready: True
Restart Count: 981
Liveness: http-get http://:10054/metrics delay=60s timeout=5s period=10s #success=1 #failure=5
Volume Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-zqbdp (ro)
Environment Variables: <none>
healthz:
Container ID: rkt://f6480fe7-4316-4e0e-9483-0944feb85ea3:healthz
Image: gcr.io/google_containers/exechealthz-amd64:v1.2.0
Image ID: rkt://sha512-3a85b0533dfba81b5083a93c7e091377123dac0942f46883a4c10c25cf0ad177
Port: 8080/TCP
Args:
--cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null
--url=/healthz-dnsmasq
--cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null
--url=/healthz-kubedns
--port=8080
--quiet
Limits:
memory: 50Mi
Requests:
cpu: 10m
memory: 50Mi
State: Running
Started: Sun, 12 Mar 2017 17:47:41 +0000
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Sun, 12 Mar 2017 17:46:28 +0000
Finished: Sun, 12 Mar 2017 17:47:02 +0000
Ready: True
Restart Count: 981
Volume Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-zqbdp (ro)
Environment Variables: <none>
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
Volumes:
default-token-zqbdp:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-zqbdp
QoS Class: Burstable
Tolerations: CriticalAddonsOnly=:Exists
No events.
which shows that kubedns-amd64:1.9 is in Ready: false
this is my kude-dns-de.yaml file:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
spec:
strategy:
rollingUpdate:
maxSurge: 10%
maxUnavailable: 0
selector:
matchLabels:
k8s-app: kube-dns
template:
metadata:
labels:
k8s-app: kube-dns
annotations:
scheduler.alpha.kubernetes.io/critical-pod: ''
scheduler.alpha.kubernetes.io/tolerations: '[{"key":"CriticalAddonsOnly", "operator":"Exists"}]'
spec:
containers:
- name: kubedns
image: gcr.io/google_containers/kubedns-amd64:1.9
resources:
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
livenessProbe:
httpGet:
path: /healthz-kubedns
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
readinessProbe:
httpGet:
path: /readiness
port: 8081
scheme: HTTP
initialDelaySeconds: 3
timeoutSeconds: 5
args:
- --domain=cluster.local.
- --dns-port=10053
- --config-map=kube-dns
# This should be set to v=2 only after the new image (cut from 1.5) has
# been released, otherwise we will flood the logs.
- --v=2
env:
- name: PROMETHEUS_PORT
value: "10055"
ports:
- containerPort: 10053
name: dns-local
protocol: UDP
- containerPort: 10053
name: dns-tcp-local
protocol: TCP
- containerPort: 10055
name: metrics
protocol: TCP
- name: dnsmasq
image: gcr.io/google_containers/kube-dnsmasq-amd64:1.4.1
livenessProbe:
httpGet:
path: /healthz-dnsmasq
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- --cache-size=1000
- --no-resolv
- --server=127.0.0.1#10053
- --log-facility=-
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
# see: https://github.com/kubernetes/kubernetes/issues/29055 for details
resources:
requests:
cpu: 150m
memory: 10Mi
- name: dnsmasq-metrics
image: gcr.io/google_containers/dnsmasq-metrics-amd64:1.0.1
livenessProbe:
httpGet:
path: /metrics
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- --v=2
- --logtostderr
ports:
- containerPort: 10054
name: metrics
protocol: TCP
resources:
requests:
memory: 10Mi
- name: healthz
image: gcr.io/google_containers/exechealthz-amd64:v1.2.0
resources:
limits:
memory: 50Mi
requests:
cpu: 10m
memory: 50Mi
args:
- --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null
- --url=/healthz-dnsmasq
- --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null
- --url=/healthz-kubedns
- --port=8080
- --quiet
ports:
- containerPort: 8080
protocol: TCP
dnsPolicy: Default
and this is my kube-dns-svc.yaml:
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: "KubeDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.3.0.10
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
any information regarding the issue would be greatly appreciated!
update
rkt list --full 2> /dev/null | grep kubedns shows:
744a4579-0849-4fae-b1f5-cb05d40f3734 kubedns gcr.io/google_containers/kubedns-amd64:1.9 sha512-c7b7c9c4393b running 2017-03-22 22:14:55.801 +0000 UTC 2017-03-22 22:14:56.814 +0000 UTC
journalctl -m _MACHINE_ID=744a45790849b1f5cb05d40f3734 provides:
Mar 22 22:17:58 kube-dns-3675956729-sthcv kubedns[8]: E0322 22:17:58.619254 8 reflector.go:199] pkg/dns/dns.go:145: Failed to list *api.Endpoints: Get https://10.3.0.1:443/api/v1/endpoints?resourceVersion=0: dial tcp 10.3.0.1:443: connect: network is unreachable
I tried to add - --proxy-mode=userspace to /etc/kubernetes/manifests/kube-proxy.yaml but the results are the same.
kubectl get svc --all-namespaces provides:
NAMESPACE NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ceph ceph-mon None <none> 6789/TCP 1h
default kubernetes 10.3.0.1 <none> 443/TCP 1h
kube-system heapster 10.3.0.2 <none> 80/TCP 1h
kube-system kube-dns 10.3.0.10 <none> 53/UDP,53/TCP 1h
kube-system kubernetes-dashboard 10.3.0.116 <none> 80/TCP 1h
kube-system monitoring-grafana 10.3.0.187 <none> 80/TCP 1h
kube-system monitoring-influxdb 10.3.0.214 <none> 8086/TCP 1h
nginx-ingress default-http-backend 10.3.0.233 <none> 80/TCP 1h
kubectl get cs provides:
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-0 Healthy {"health": "true"}
my kube-proxy.yaml has the following content:
apiVersion: v1
kind: Pod
metadata:
name: kube-proxy
namespace: kube-system
annotations:
rkt.alpha.kubernetes.io/stage1-name-override: coreos.com/rkt/stage1-fly
spec:
hostNetwork: true
containers:
- name: kube-proxy
image: quay.io/coreos/hyperkube:v1.5.5_coreos.0
command:
- /hyperkube
- proxy
- --cluster-cidr=10.2.0.0/16
- --kubeconfig=/etc/kubernetes/controller-kubeconfig.yaml
securityContext:
privileged: true
volumeMounts:
- mountPath: /etc/ssl/certs
name: "ssl-certs"
- mountPath: /etc/kubernetes/controller-kubeconfig.yaml
name: "kubeconfig"
readOnly: true
- mountPath: /etc/kubernetes/ssl
name: "etc-kube-ssl"
readOnly: true
- mountPath: /var/run/dbus
name: dbus
readOnly: false
volumes:
- hostPath:
path: "/usr/share/ca-certificates"
name: "ssl-certs"
- hostPath:
path: "/etc/kubernetes/controller-kubeconfig.yaml"
name: "kubeconfig"
- hostPath:
path: "/etc/kubernetes/ssl"
name: "etc-kube-ssl"
- hostPath:
path: /var/run/dbus
name: dbus
this is all the valuable information I could find. any ideas? :)
update 2
output of iptables-save on the controller ContainerOS at http://pastebin.com/2GApCj0n
update 3
I ran curl on the controller node
# curl https://10.3.0.1 --insecure
Unauthorized
means it can access it properly, i didn't add enough parameters for it to be authorized right ?
update 4
thanks to #jaxxstorm I removed calico manifests, updated their quay/cni and quay/node versions and reinstalled them.
now kubedns keeps restarting, but I think that now calico works. because for the first time it tries to install kubedns on the worker node and not on the controller node, and also when I rkt enter the kubedns pod and try to wget https://10.3.0.1 I get:
# wget https://10.3.0.1
Connecting to 10.3.0.1 (10.3.0.1:443)
wget: can't execute 'ssl_helper': No such file or directory
wget: error getting response: Connection reset by peer
which clearly shows that there is some kind of response. which is good right ?
now kubectl get pods --all-namespaces shows:
kube-system kube-dns-3675956729-ljz2w 4/4 Running 88 42m
so.. 4/4 ready but it keeps restarting.
kubectl describe pod kube-dns-3675956729-ljz2w --namespace=kube-system output at http://pastebin.com/Z70U331G
so it can't connect to http://10.2.47.19:8081/readiness, i'm guessing this is the ip of kubedns since it uses port 8081. don't know how to continue investigating this issue further.
thanks for everything!

Answer 1

Lots of great debugging info here, thanks!
This is the clincher:
# curl https://10.3.0.1 --insecure
Unauthorized
You got an unauthorized response because you didn't pass a client cert, but that's fine, it's not what we're after. This proves that kube-proxy is working as expected and is accessible. Your rkt logs:
Mar 22 22:17:58 kube-dns-3675956729-sthcv kubedns[8]: E0322 22:17:58.619254 8 reflector.go:199] pkg/dns/dns.go:145: Failed to list *api.Endpoints: Get https://10.3.0.1:443/api/v1/endpoints?resourceVersion=0: dial tcp 10.3.0.1:443: connect: network is unreachable
Are indicating that the containers that there's network connectivity issues inside the containers, which indicates to me that you haven't configured container networking/CNI.
Please have a read through this document: https://coreos.com/rkt/docs/latest/networking/overview.html
You may also have to reconfigure calico, there's some more information that here: http://docs.projectcalico.org/master/getting-started/rkt/

Answer 2

kube-dns has a readiness probe that tries resolving trough the Service IP of kube-dns. Is it possible that there is a problem with your Service network?
Check out the answer and solution here:
kubernetes service IPs not reachable