I am following link: https://kubernetes.dask.org/en/latest/, to run dask array on Kubernetes cluster. While running the example code, the worker pod is showing error status as below:
Steps:
Installed Kubernetes on 3 nodes(1 Master and 2 workers).
pip install dask-kubernetes
dask_example.py with code to run dask array (same as example given on link)
Worker-spec.yml file with pod configuration (same as example given on link)
(base) [root@k8s-master example]# ls
dask_example.py worker-spec.yml
(base) [root@k8s-master example]# nohup python dask_example.py &
[1] 3660
(base) [root@k8s-master example]# cat nohup.out
distributed.scheduler - INFO - Clear task state
distributed.scheduler - INFO - Scheduler at: tcp://172.16.0.76:40119
distributed.scheduler - INFO - Receive client connection: Client-df4caa18-0bc8-11ea-8e4c-12bd5ffa93ff
distributed.core - INFO - Starting established connection
(base) [root@k8s-master example]# kubectl get pods -o wide --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
default workerpod 1/1 Running 0 70s 10.32.0.2 worker-node1 <none> <none>
kube-system coredns-5644d7b6d9-l4jsd 1/1 Running 0 8m19s 10.32.0.4 k8s-master <none> <none>
kube-system coredns-5644d7b6d9-q679h 1/1 Running 0 8m19s 10.32.0.3 k8s-master <none> <none>
kube-system etcd-k8s-master 1/1 Running 0 7m16s 172.16.0.76 k8s-master <none> <none>
kube-system kube-apiserver-k8s-master 1/1 Running 0 7m1s 172.16.0.76 k8s-master <none> <none>
kube-system kube-controller-manager-k8s-master 1/1 Running 0 7m27s 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ctgj8 1/1 Running 0 5m7s 172.16.0.114 worker-node2 <none> <none>
kube-system kube-proxy-f78bm 1/1 Running 0 8m18s 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ksk59 1/1 Running 0 5m15s 172.16.0.31 worker-node1 <none> <none>
kube-system kube-scheduler-k8s-master 1/1 Running 0 7m2s 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-q2zwn 2/2 Running 0 6m22s 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-r9tzs 2/2 Running 0 5m15s 172.16.0.31 worker-node1 <none> <none>
kube-system weave-net-tm8xx 2/2 Running 0 5m7s 172.16.0.114 worker-node2 <none> <none>
(base) [root@k8s-master example]# kubectl get pods -o wide --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
default workerpod 0/1 Error 0 4m23s 10.32.0.2 worker-node1 <none> <none>
kube-system coredns-5644d7b6d9-l4jsd 1/1 Running 0 11m 10.32.0.4 k8s-master <none> <none>
kube-system coredns-5644d7b6d9-q679h 1/1 Running 0 11m 10.32.0.3 k8s-master <none> <none>
kube-system etcd-k8s-master 1/1 Running 0 10m 172.16.0.76 k8s-master <none> <none>
kube-system kube-apiserver-k8s-master 1/1 Running 0 10m 172.16.0.76 k8s-master <none> <none>
kube-system kube-controller-manager-k8s-master 1/1 Running 0 10m 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ctgj8 1/1 Running 0 8m20s 172.16.0.114 worker-node2 <none> <none>
kube-system kube-proxy-f78bm 1/1 Running 0 11m 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ksk59 1/1 Running 0 8m28s 172.16.0.31 worker-node1 <none> <none>
kube-system kube-scheduler-k8s-master 1/1 Running 0 10m 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-q2zwn 2/2 Running 0 9m35s 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-r9tzs 2/2 Running 0 8m28s 172.16.0.31 worker-node1 <none> <none>
kube-system weave-net-tm8xx 2/2 Running 0 8m20s 172.16.0.114 worker-node2 <none> <none>
(base) [root@k8s-master example]# cat nohup.out
distributed.scheduler - INFO - Clear task state
distributed.scheduler - INFO - Scheduler at: tcp://172.16.0.76:40119
distributed.scheduler - INFO - Receive client connection: Client-df4caa18-0bc8-11ea-8e4c-12bd5ffa93ff
distributed.core - INFO - Starting established connection
(base) [root@k8s-master example]# kubectl describe pod workerpod
Name: workerpod
Namespace: default
Priority: 0
Node: worker-node1/172.16.0.31
Start Time: Wed, 20 Nov 2019 19:06:36 +0000
Labels: app=dask
dask.org/cluster-name=dask-root-99dcf768-4
dask.org/component=worker
foo=bar
user=root
Annotations: <none>
Status: Failed
IP: 10.32.0.2
IPs:
IP: 10.32.0.2
Containers:
dask:
Container ID: docker://578dc575fc263c4a3889a4f2cb5e06cd82a00e03cfc6acfd7a98fef703421390
Image: daskdev/dask:latest
Image ID: docker-pullable://daskdev/dask@sha256:0a936daa94c82cea371c19a2c90c695688ab4e1e7acc905f8b30dfd419adfb6f
Port: <none>
Host Port: <none>
Args:
dask-worker
--nthreads
2
--no-bokeh
--memory-limit
6GB
--death-timeout
60
State: Terminated
Reason: Error
Exit Code: 1
Started: Wed, 20 Nov 2019 19:06:38 +0000
Finished: Wed, 20 Nov 2019 19:08:20 +0000
Ready: False
Restart Count: 0
Limits:
cpu: 2
memory: 6G
Requests:
cpu: 2
memory: 6G
Environment:
EXTRA_PIP_PACKAGES: fastparquet git+https://github.com/dask/distributed
DASK_SCHEDULER_ADDRESS: tcp://172.16.0.76:40119
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-p9f9v (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-p9f9v:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-p9f9v
Optional: false
QoS Class: Guaranteed
Node-Selectors: <none>
Tolerations: k8s.dask.org/dedicated=worker:NoSchedule
k8s.dask.org_dedicated=worker:NoSchedule
node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 5m47s default-scheduler Successfully assigned default/workerpod to worker-node1
Normal Pulled 5m45s kubelet, worker-node1 Container image "daskdev/dask:latest" already present on machine
Normal Created 5m45s kubelet, worker-node1 Created container dask
Normal Started 5m45s kubelet, worker-node1 Started container dask
(base) [root@k8s-master example]#
(base) [root@k8s-master example]# kubectl get events
LAST SEEN TYPE REASON OBJECT MESSAGE
21m Normal Starting node/k8s-master Starting kubelet.
21m Normal NodeHasSufficientMemory node/k8s-master Node k8s-master status is now: NodeHasSufficientMemory
21m Normal NodeHasNoDiskPressure node/k8s-master Node k8s-master status is now: NodeHasNoDiskPressure
21m Normal NodeHasSufficientPID node/k8s-master Node k8s-master status is now: NodeHasSufficientPID
21m Normal NodeAllocatableEnforced node/k8s-master Updated Node Allocatable limit across pods
21m Normal RegisteredNode node/k8s-master Node k8s-master event: Registered Node k8s-master in Controller
21m Normal Starting node/k8s-master Starting kube-proxy.
18m Normal Starting node/worker-node1 Starting kubelet.
18m Normal NodeHasSufficientMemory node/worker-node1 Node worker-node1 status is now: NodeHasSufficientMemory
18m Normal NodeHasNoDiskPressure node/worker-node1 Node worker-node1 status is now: NodeHasNoDiskPressure
18m Normal NodeHasSufficientPID node/worker-node1 Node worker-node1 status is now: NodeHasSufficientPID
18m Normal NodeAllocatableEnforced node/worker-node1 Updated Node Allocatable limit across pods
18m Normal Starting node/worker-node1 Starting kube-proxy.
18m Normal RegisteredNode node/worker-node1 Node worker-node1 event: Registered Node worker-node1 in Controller
17m Normal NodeReady node/worker-node1 Node worker-node1 status is now: NodeReady
18m Normal Starting node/worker-node2 Starting kubelet.
18m Normal NodeHasSufficientMemory node/worker-node2 Node worker-node2 status is now: NodeHasSufficientMemory
18m Normal NodeHasNoDiskPressure node/worker-node2 Node worker-node2 status is now: NodeHasNoDiskPressure
18m Normal NodeHasSufficientPID node/worker-node2 Node worker-node2 status is now: NodeHasSufficientPID
18m Normal NodeAllocatableEnforced node/worker-node2 Updated Node Allocatable limit across pods
18m Normal Starting node/worker-node2 Starting kube-proxy.
17m Normal RegisteredNode node/worker-node2 Node worker-node2 event: Registered Node worker-node2 in Controller
17m Normal NodeReady node/worker-node2 Node worker-node2 status is now: NodeReady
14m Normal Scheduled pod/workerpod Successfully assigned default/workerpod to worker-node1
14m Normal Pulled pod/workerpod Container image "daskdev/dask:latest" already present on machine
14m Normal Created pod/workerpod Created container dask
14m Normal Started pod/workerpod Started container dask
(base) [root@k8s-master example]#
Update- adding pod logs (as suggested by Dawid Kruk):
(base) [root@k8s-master example]# kubectl logs workerpod
+ '[' '' ']'
+ '[' -e /opt/app/environment.yml ']'
+ echo 'no environment.yml'
+ '[' '' ']'
+ '[' 'fastparquet git+https://github.com/dask/distributed' ']'
+ echo 'EXTRA_PIP_PACKAGES environment variable found. Installing.'
+ /opt/conda/bin/pip install fastparquet git+https://github.com/dask/distributed
no environment.yml
EXTRA_PIP_PACKAGES environment variable found. Installing.
Collecting git+https://github.com/dask/distributed
Cloning https://github.com/dask/distributed to /tmp/pip-req-build-i3_1vo06
Running command git clone -q https://github.com/dask/distributed /tmp/pip-req-build-i3_1vo06
fatal: unable to access 'https://github.com/dask/distributed/': Could not resolve host: github.com
ERROR: Command errored out with exit status 128: git clone -q https://github.com/dask/distributed /tmp/pip-req-build-i3_1vo06 Check the logs for full command output.
+ exec dask-worker --nthreads 2 --no-bokeh --memory-limit 6GB --death-timeout 60
/opt/conda/lib/python3.7/site-packages/distributed/cli/dask_worker.py:252: UserWarning: The --bokeh/--no-bokeh flag has been renamed to --dashboard/--no-dashboard.
"The --bokeh/--no-bokeh flag has been renamed to --dashboard/--no-dashboard. "
distributed.nanny - INFO - Start Nanny at: 'tcp://10.32.0.2:45097'
distributed.worker - INFO - Start worker at: tcp://10.32.0.2:36389
distributed.worker - INFO - Listening to: tcp://10.32.0.2:36389
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.worker - INFO - -------------------------------------------------
distributed.worker - INFO - Threads: 2
distributed.worker - INFO - Memory: 6.00 GB
distributed.worker - INFO - Local Directory: /worker-55rpow8j
distributed.worker - INFO - -------------------------------------------------
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.worker - INFO - Waiting to connect to: tcp://172.16.0.76:43389
distributed.nanny - INFO - Closing Nanny at 'tcp://10.32.0.2:45097'
distributed.worker - INFO - Stopping worker at tcp://10.32.0.2:36389
distributed.worker - INFO - Closed worker has not yet started: None
distributed.dask_worker - INFO - Timed out starting worker
distributed.dask_worker - INFO - End worker
(base) [root@k8s-master example]# git
usage: git [--version] [--help] [-C <path>] [-c <name>=<value>]
[--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
Seems to me like dask pod connection to worker node is issue but I see worker nodes in ready state and other pods (nginx) are running on worker nodes:
(base) [root@k8s-master example]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready master 20h v1.16.3
worker-node1 Ready worker 20h v1.16.2
worker-node2 Ready worker 20h v1.16.2
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
default nginx-deployment-54f57cf6bf-b9nfd 1/1 Running 0 34s 10.32.0.2 worker-node1 <none> <none>
default nginx-deployment-54f57cf6bf-pnp59 1/1 Running 0 34s 10.40.0.0 worker-node2 <none> <none>
default workerpod 0/1 Error 0 56m 10.32.0.2 worker-node1 <none> <none>
kube-system coredns-5644d7b6d9-l4jsd 1/1 Running 0 21h 10.32.0.4 k8s-master <none> <none>
kube-system coredns-5644d7b6d9-q679h 1/1 Running 0 21h 10.32.0.3 k8s-master <none> <none>
kube-system etcd-k8s-master 1/1 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system kube-apiserver-k8s-master 1/1 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system kube-controller-manager-k8s-master 1/1 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ctgj8 1/1 Running 0 21h 172.16.0.114 worker-node2 <none> <none>
kube-system kube-proxy-f78bm 1/1 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system kube-proxy-ksk59 1/1 Running 0 21h 172.16.0.31 worker-node1 <none> <none>
kube-system kube-scheduler-k8s-master 1/1 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-q2zwn 2/2 Running 0 21h 172.16.0.76 k8s-master <none> <none>
kube-system weave-net-r9tzs 2/2 Running 0 21h 172.16.0.31 worker-node1 <none> <none>
kube-system weave-net-tm8xx 2/2 Running 0 21h 172.16.0.114 worker-node2 <none> <none>
Update2 - Added nslookup output (Suggested by VAS) Ref: https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/#create-a-simple-pod-to-use-as-a-test-environment
(base) [root@k8s-master example]# kubectl exec -ti workerpod -- nslookup kubernetes.default
OCI runtime exec failed: exec failed: container_linux.go:345: starting container process caused "exec: \"nslookup\": executable file not found in $PATH": unknown
command terminated with exit code 126
How to add executable file to pod? It is set on my host.
(base) [root@k8s-master example]# nslookup github.com
Server: 172.31.0.2
Address: 172.31.0.2#53
Non-authoritative answer:
Name: github.com
Address: 140.82.114.3
Update 3: nslookup for dnsutils (Suggested by VAS)
(base) [root@k8s-master example]# kubectl run dnsutils -it --rm=true --restart=Never --image=tutum/dnsutils cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local ec2.internal
options ndots:5
pod "dnsutils" deleted
(base) [root@k8s-master example]# kubectl run dnsutils -it --restart=Never --image=tutum/dnsutils nslookup github.com
If you don't see a command prompt, try pressing enter.
;; connection timed out; no servers could be reached
pod default/dnsutils terminated (Error)
(base) [root@k8s-master example]# kubectl logs dnsutils
;; connection timed out; no servers could be reached
(base) [root@k8s-master example]#
Update 4:
(base) [root@k8s-master example]# kubectl exec -ti busybox -- nslookup kubernetes.default
Server: 10.96.0.10
Address 1: 10.96.0.10
nslookup: can't resolve 'kubernetes.default'
command terminated with exit code 1
(base) [root@k8s-master example]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
coredns-5644d7b6d9-l4jsd 1/1 Running 0 25h
coredns-5644d7b6d9-q679h 1/1 Running 0 25h
(base) [root@k8s-master example]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
coredns-5644d7b6d9-l4jsd 1/1 Running 0 25h
coredns-5644d7b6d9-q679h 1/1 Running 0 25h
(base) [root@k8s-master example]# for p in $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name); do kubectl logs --namespace=kube-system $p; done
.:53
2019-11-20T19:01:42.161Z [INFO] plugin/reload: Running configuration MD5 = f64cb9b977c7dfca58c4fab108535a76
2019-11-20T19:01:42.161Z [INFO] CoreDNS-1.6.2
2019-11-20T19:01:42.161Z [INFO] linux/amd64, go1.12.8, 795a3eb
CoreDNS-1.6.2
linux/amd64, go1.12.8, 795a3eb
.:53
2019-11-20T19:01:41.862Z [INFO] plugin/reload: Running configuration MD5 = f64cb9b977c7dfca58c4fab108535a76
2019-11-20T19:01:41.862Z [INFO] CoreDNS-1.6.2
2019-11-20T19:01:41.862Z [INFO] linux/amd64, go1.12.8, 795a3eb
CoreDNS-1.6.2
linux/amd64, go1.12.8, 795a3eb
(base) [root@k8s-master example]# kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 26h
(base) [root@k8s-master example]# kubectl get ep kube-dns --namespace=kube-system
NAME ENDPOINTS AGE
kube-dns 10.32.0.3:53,10.32.0.4:53,10.32.0.3:53 + 3 more... 26h
(base) [root@k8s-master example]# kubectl -n kube-system edit configmap coredns
Edit cancelled, no changes made.
nslookup from worker node1
[root@worker-node1 ec2-user]# nslookup 10.96.0.10
Server: 172.31.0.2
Address: 172.31.0.2#53
Non-authoritative answer:
10.0.96.10.in-addr.arpa name = ip-10-96-0-10.ec2.internal.
Authoritative answers can be found from:
[root@worker-node1 ec2-user]# nslookup 10.96.0.1
Server: 172.31.0.2
Address: 172.31.0.2#53
Non-authoritative answer:
1.0.96.10.in-addr.arpa name = ip-10-96-0-1.ec2.internal.
Authoritative answers can be found from:
[root@worker-node1 ec2-user]#
nslookup from worker node2
[root@worker-node2 ec2-user]# nslookup 10.96.0.10
Server: 172.31.0.2
Address: 172.31.0.2#53
Non-authoritative answer:
10.0.96.10.in-addr.arpa name = ip-10-96-0-10.ec2.internal.
Authoritative answers can be found from:
[root@worker-node2 ec2-user]# nslookup 10.96.0.1
Server: 172.31.0.2
Address: 172.31.0.2#53
Non-authoritative answer:
1.0.96.10.in-addr.arpa name = ip-10-96-0-1.ec2.internal.
Authoritative answers can be found from:
Update:
As I can see from the comments, I also need to cover some basic concepts in the answer.
To ensure that Kubernetes cluster works well some requirements should be fulfilled.
All Kubernetes nodes must have full network connectivity.
It means that any cluster node should be able to communicate with any other cluster node using any network protocol and any port (in case of tcp/udp), without NAT. Some cloud environments require additional custom firewall rules to accomplish that. Calico example
Kubernetes Pods should be able to communicate with pods scheduled on the other nodes.
This functionality is provided by [CNI network add-on]. Most popular add-ons require additional option in Kubernetes control plane, which usually set by kubeadm init --pod-network-cidr=a.b.c.d/16 command line option. Note, that default IP subnets for different network add-ons are not the same.
If you want to use custom Pod subnet for the particular network add-on, you have to customize network add-on deployment YAML file before applying it to the cluster.
The inter Pod connectivity could be easily tested by sending ICMP or curl requests from node CLI or Pod CLI to any IP address of Pod, scheduled on another node. Note, that Service ClusterIP doesn't respond on ICMP requests, because it's nothing more that set of iptables forwarding rules. The full list of pods with node names could be showed using the following command:
kubectl get pods --all-namespaces -o wide
kubedns for Kubernetes versions prior v1.9 and coredns for newer clusters.Looking at the data in the question I suspect that you may have problem with network add-on. I would test it using the following commands, which should return successful results on the healthy cluster:
# check connectivity from the master node to nginx pods:
k8s-master$ ping 10.32.0.2
k8s-master$ curl 10.32.0.2
k8s-master$ ping 10.40.0.0
k8s-master$ curl 10.40.0.0
# check connectivity from other nodes to coredns pods and DNS Service:
worker-node1$ nslookup github.com 10.32.0.4
worker-node1$ nslookup github.com 10.32.0.3
worker-node1$ nslookup github.com 10.96.0.10
worker-node2$ nslookup github.com 10.32.0.4
worker-node2$ nslookup github.com 10.32.0.3
worker-node2$ nslookup github.com 10.96.0.10
Troubleshooting network plugin is a quite big piece of knowledge to write in one answer, so, if you need to fix network add-on, please do some search through existing answers and ask another question in case you found nothing suitable.
Below part describes how to check DNS service in Kubernetes cluster:
In case of dnsPolicy ClusterFirst(which is default) any DNS query that does not match the configured cluster domain suffix, such as “www.kubernetes.io”, is forwarded to the upstream nameserver inherited from the node.
How to check DNS client configuration on the cluster node:
$ cat /etc/resolv.conf
$ systemd-resolve --status
How to check if DNS client on the node works well:
$ nslookup github.com
Server: 127.0.0.53
Address: 127.0.0.53#53
Non-authoritative answer:
Name: github.com
Address: 140.82.118.4
How to get Kubernetes cluster DNS configuration:
$ kubectl get svc,pods -n kube-system -o wide | grep dns
service/kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 185d k8s-app=kube-dns
pod/coredns-fb8b8dccf-5jjv8 1/1 Running 122 185d 10.244.0.16 kube-master2 <none> <none>
pod/coredns-fb8b8dccf-5pbkg 1/1 Running 122 185d 10.244.0.17 kube-master2 <none> <none>
$ kubectl get configmap coredns -n kube-system -o yaml
apiVersion: v1
data:
Corefile: |
.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
kind: ConfigMap
metadata:
creationTimestamp: "2019-05-20T16:10:42Z"
name: coredns
namespace: kube-system
resourceVersion: "1657005"
selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
uid: d1598034-7b19-11e9-9137-42010a9c0004
How to check if the cluster DNS service (coredns) works well:
$ nslookup github.com 10.96.0.10
Server: 10.96.0.10
Address: 10.96.0.10#53
Non-authoritative answer:
Name: github.com
Address: 140.82.118.4
How to check if the regular pod can resolve particular DNS name:
$ kubectl run dnsutils -it --rm=true --restart=Never --image=tutum/dnsutils cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5
$ kubectl run dnsutils -it --rm=true --restart=Never --image=tutum/dnsutils nslookup github.com
Server: 10.96.0.10
Address: 10.96.0.10#53
Non-authoritative answer:
Name: github.com
Address: 140.82.118.3
More details about DNS troubleshooting can be found in the official documentation