Kube-dns always in pending state - kubernetes

Question

I have deployed kubernetes on a virt-manager vm following this link
https://kubernetes.io/docs/setup/independent/install-kubeadm/
When i join my another vm to the cluster i find that the kube-dns is in pending state.
root#ubuntu1:~# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-ubuntu1 1/1 Running 0 7m
kube-system kube-apiserver-ubuntu1 1/1 Running 0 8m
kube-system kube-controller-manager-ubuntu1 1/1 Running 0 8m
kube-system kube-dns-86f4d74b45-br6ck 0/3 Pending 0 8m
kube-system kube-proxy-sh9lg 1/1 Running 0 8m
kube-system kube-proxy-zwdt5 1/1 Running 0 7m
kube-system kube-scheduler-ubuntu1 1/1 Running 0 8m
root#ubuntu1:~# kubectl --namespace=kube-system describe pod kube-dns-86f4d74b45-br6ck
Name: kube-dns-86f4d74b45-br6ck
Namespace: kube-system
Node: <none>
Labels: k8s-app=kube-dns
pod-template-hash=4290830601
Annotations: <none>
Status: Pending
IP:
Controlled By: ReplicaSet/kube-dns-86f4d74b45
Containers:
kubedns:
Image: k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8
Ports: 10053/UDP, 10053/TCP, 10055/TCP
Host Ports: 0/UDP, 0/TCP, 0/TCP
Args:
--domain=cluster.local.
--dns-port=10053
--config-dir=/kube-dns-config
--v=2
Limits:
memory: 170Mi
Requests:
cpu: 100m
memory: 70Mi
Liveness: http-get http://:10054/healthcheck/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
Environment:
PROMETHEUS_PORT: 10055
Mounts:
/kube-dns-config from kube-dns-config (rw)
/var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
dnsmasq:
Image: k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8
Ports: 53/UDP, 53/TCP
Host Ports: 0/UDP, 0/TCP
Args:
-v=2
-logtostderr
-configDir=/etc/k8s/dns/dnsmasq-nanny
-restartDnsmasq=true
--
-k
--cache-size=1000
--no-negcache
--log-facility=-
--server=/cluster.local/127.0.0.1#10053
--server=/in-addr.arpa/127.0.0.1#10053
--server=/ip6.arpa/127.0.0.1#10053
Requests:
cpu: 150m
memory: 20Mi
Liveness: http-get http://:10054/healthcheck/dnsmasq delay=60s timeout=5s period=10s #success=1 #failure=5
Environment: <none>
Mounts:
/etc/k8s/dns/dnsmasq-nanny from kube-dns-config (rw)
/var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
sidecar:
Image: k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8
Port: 10054/TCP
Host Port: 0/TCP
Args:
--v=2
--logtostderr
--probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local,5,SRV
--probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local,5,SRV
Requests:
cpu: 10m
memory: 20Mi
Liveness: http-get http://:10054/metrics delay=60s timeout=5s period=10s #success=1 #failure=5
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
Conditions:
Type Status
PodScheduled False
Volumes:
kube-dns-config:
Type: ConfigMap (a volume populated by a ConfigMap)
Name: kube-dns
Optional: true
kube-dns-token-4fjt4:
Type: Secret (a volume populated by a Secret)
SecretName: kube-dns-token-4fjt4
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 6m (x7 over 7m) default-scheduler 0/1 nodes are available: 1 node(s) were not ready.
Warning FailedScheduling 3s (x19 over 6m) default-scheduler 0/2 nodes are available: 2 node(s) were not ready.
Can anyone just help me how to deconstruct this and find the actual issue??
Any help would be off great use
Thanks in advance.

Answer 1

In addition to what #justcompile has wrote you will need a minimum of 2 CPU cores in order to run all pods from the kube-system namespace without issues.
You need to verify how much resources you have on that box and compare it with CPU reservations which each of Pods make.
For example in the provided by you output I can see that your DNS service tries to make a reservetion for 10% of CPU core:
Requests:
cpu: 100m
You can check each of deployed pods and their CPU reservations using:
kubectl describe pods --namespace=kube-system

Answer 2

in your cause kubectl get pods --all-namespaces output cannot see any about pods network.
so you may choice a network implementation and have to install a Pod Network before then kube-dns may deployed fully. for detail kube-dns is stuck in the Pending state and install pod network solution

Answer 3

Firstly, if you run kubectl get nodes does this show both/all nodes in a Ready state?
If they are, I faced this problem and found that when inspecting kubectl get events it showed that the pods were failing as they required a minimum of 2 CPUs to run.
As I was initially running this on an old Macbook Pro via VirtualBox I had to give up and use AWS (other Cloud Platforms are of course available) in order to get multiple CPUs per node.