k8s中因busybox镜像版本问题导致Pod中nslookup无法解析Service名称问题

1.创建busybox的Pod

vim dns.yml

apiVersion: v1
kind: Pod
metadata:
  name: dns
spec:
  containers:
  - image: busybox
    name: busybox
    command:
    - /bin/sh
    - -c
    - 'sleep 3600'

或者

kubectl run dns --image=busybox --command -- /bin/sh -c 'sleep 3600'

2.进入busybox的Pod，测试nslookup

kubectl exec -it dns -- /bin/sh

nslookup解析Service名称nginx

[root@master01 cka]# kubectl exec -it dns -- /bin/sh
/ # nslookup nginx
Server:		10.96.0.10
Address:	10.96.0.10:53

** server can't find nginx.default.svc.cluster.local: NXDOMAIN

*** Can't find nginx.svc.cluster.local: No answer
*** Can't find nginx.cluster.local: No answer
*** Can't find nginx.default.svc.cluster.local: No answer
*** Can't find nginx.svc.cluster.local: No answer
*** Can't find nginx.cluster.local: No answer

可以看到新版本的busybox无法正常解析集群中Service名称

3.更改busybox镜像的版本，使用1.28.3

vim dns.yml

apiVersion: v1
kind: Pod
metadata:
  name: dns
spec:
  containers:
  - image: busybox:1.28.3
    name: busybox
    command:
    - /bin/sh
    - -c
    - 'sleep 3600'

kubectl apply -f dns.yml

或者

kubectl set image Pod dns busybox=busybox:1.28.3

4.进入Pod，测试nslookup命令

[root@master01 cka]# kubectl exec -it dns -- /bin/sh
/ # nslookup nginx
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      nginx
Address 1: 10.99.29.162 nginx.default.svc.cluster.local

可以看到，使用busybox:1.28.3镜像，nslookup命令已经可以正常解析Service名称nginx了。