Kubernetes coredns pods not running in every pods - kubernetes

Question

With new installation of Kubernetes on Ubuntu with one master and two nodes,
root#master1# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
master1 Ready master 10h v1.19.3 10.10.10.216 <none> Ubuntu 18.04.5 LTS 4.15.0-122-generic docker://19.3.13
worker1 Ready <none> 10h v1.19.3 10.10.10.211 <none> Ubuntu 18.04.5 LTS 4.15.0-122-generic docker://19.3.13
worker2 Ready <none> 10h v1.19.3 10.10.10.212 <none> Ubuntu 18.04.5 LTS 4.15.0-122-generic docker://19.3.13
i check if all pods in namespace kube-system works.
root#master1:# kubectl get pods -A -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
kube-system coredns-f9fd979d6-cggnh 1/1 Running 0 10h 10.244.0.2 master1 <none> <none>
kube-system coredns-f9fd979d6-tnm7c 1/1 Running 0 10h 10.244.0.3 master1 <none> <none>
kube-system etcd-master1 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
kube-system kube-apiserver-master1 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
kube-system kube-controller-manager-master1 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
kube-system kube-flannel-ds-9ph5c 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
kube-system kube-flannel-ds-fjkng 1/1 Running 0 10h 10.10.10.212 worker2 <none> <none>
kube-system kube-flannel-ds-rfkqd 1/1 Running 0 9h 10.10.10.211 worker1 <none> <none>
kube-system kube-proxy-j7s2m 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
kube-system kube-proxy-n7279 1/1 Running 0 10h 10.10.10.212 worker2 <none> <none>
kube-system kube-proxy-vkb66 1/1 Running 0 9h 10.10.10.211 worker1 <none> <none>
kube-system kube-scheduler-master1 1/1 Running 0 10h 10.10.10.216 master1 <none> <none>
I see that coredns is work only in master with two pods
How i should do to replicate coredns in all my 3 vm (master + 2 nodes)
this is the description of coredns deployment
root#master1:# kubectl describe deployment coredns -n kube-system
Name: coredns
Namespace: kube-system
CreationTimestamp: Wed, 04 Nov 2020 20:32:10 +0000
Labels: k8s-app=kube-dns
Annotations: deployment.kubernetes.io/revision: 1
Selector: k8s-app=kube-dns
Replicas: 2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 25% max surge
Pod Template:
Labels: k8s-app=kube-dns
Service Account: coredns
Containers:
coredns:
Image: k8s.gcr.io/coredns:1.7.0
Ports: 53/UDP, 53/TCP, 9153/TCP
Host Ports: 0/UDP, 0/TCP, 0/TCP
Args:
-conf
/etc/coredns/Corefile
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)
Volumes:
config-volume:
Type: ConfigMap (a volume populated by a ConfigMap)
Name: coredns
Optional: false
Priority Class Name: system-cluster-critical
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: coredns-f9fd979d6 (2/2 replicas created)
Events: <none>
also , the logs and the stats of deployment
root#master1# kubectl logs deployment/coredns -n kube-system
Found 2 pods, using pod/coredns-f9fd979d6-cggnh
.:53
[INFO] plugin/reload: Running configuration MD5 = db32ca3650231d74073ff4cf814959a7
CoreDNS-1.7.0
linux/amd64, go1.14.4, f59c03d
root#master1:# kubectl get deployment -o wide -n kube-system
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
coredns 2/2 2 2 10h coredns k8s.gcr.io/coredns:1.7.0 k8s-app=kube-dns

Answer 1

Andre, you can add podAntiAffinity to your coredns definition:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchLabels:
k8s-app: kube-dns
topologyKey: kubernetes.io/hostname
This will let your coredns replicas scheduling to different nodes.