关于k8s解析不到pod dns信息

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/scylhy/article/details/85342452

关于k8s解析不到pod dns信息

这其实是自己对k8s的dns解析不理解，service和pod在k8s中的dns记录形式不同，  
service是通过名字的，pod是用ip的（192-168-0-1的形式）。
但是，通过pod-ip访问，很傻，已经知道ip,那还查什么，于是乎，又有了  
pod-hostname.subdomain.ns.cluster.local的方式；需要在pod spec中配置  
hostname和subdomain

• busybox:1.28，latest版本不行

apiVersion: v1
kind: Service
metadata:
  name: default-subdomain
spec:
  selector:
    name: busybox
  clusterIP: None
  ports:
  - name: foo # Actually, no port is needed.
    port: 1234
    targetPort: 1234
---
apiVersion: v1
kind: Pod
metadata:
  name: busybox1
  labels:
    name: busybox
spec:
  hostname: busybox-1
  subdomain: default-subdomain
  containers:
  - image: busybox:1.28
    command:
      - sleep
      - "3600"
    name: busybox
---
apiVersion: v1
kind: Pod
metadata:
  name: busybox2
  labels:
    name: busybox
spec:
  hostname: busybox-2
  subdomain: default-subdomain
  containers:
  - image: busybox:1.28
    command:
      - sleep
      - "3600"
    name: busybox

• service

[root@cce-demo1522483688765-00274 cka]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
http         ClusterIP   10.247.44.63     <none>        8080/TCP   3d
kubernetes   ClusterIP   10.247.0.1       <none>        443/TCP    3d
mydb         ClusterIP   10.247.6.172     <none>        80/TCP     2h
myservice    ClusterIP   10.247.148.200   <none>        80/TCP     2h
[root@cce-demo1522483688765-00274 cka]# kubectl exec -it busybox1 -- nslookup http
Server:    10.247.3.10
Address 1: 10.247.3.10 kube-dns.kube-system.svc.cluster.local

Name:      http
Address 1: 10.247.44.63 http.default.svc.cluster.local
[root@cce-demo1522483688765-00274 cka]# 

• pod

[root@cce-demo1522483688765-00274 cka]# kubectl get pods -owide
NAME                    READY     STATUS    RESTARTS   AGE       IP            NODE
busybox1                1/1       Running   0          28m       172.16.0.32   192.168.0.151
busybox2                1/1       Running   0          21m       172.16.0.26   192.168.0.151
counter                 1/1       Running   0          1h        172.16.0.22   192.168.0.151
http-7767dd48cf-cpthr   1/1       Running   0          1d        172.16.0.31   192.168.0.151
http-7767dd48cf-f5mfd   1/1       Running   0          1d        172.16.0.29   192.168.0.151
http2-fbb647ddf-gv267   1/1       Running   0          1d        172.16.0.30   192.168.0.151
myapp-pod2              1/1       Running   2          2h        172.16.0.16   192.168.0.151
non-persistent-redis    1/1       Running   1          1h        172.16.0.20   192.168.0.151
task-pv-pod             1/1       Running   0          1h        172.16.0.19   192.168.0.151
[root@cce-demo1522483688765-00274 cka]# kubectl exec -it busybox1 -- nslookup 172-16-0-22.default.pod.cluster.local
Server:    10.247.3.10
Address 1: 10.247.3.10 kube-dns.kube-system.svc.cluster.local

Name:      172-16-0-22.default.pod.cluster.local
Address 1: 172.16.0.22
[root@cce-demo1522483688765-00274 cka]# 


root@lhys:~# kubectl exec -it busybox1 -- nslookup default-subdomain
Server:    10.247.3.10
Address 1: 10.247.3.10 coredns.kube-system.svc.cluster.local

Name:      default-subdomain
Address 1: 172.16.0.9 busybox-2.default-subdomain.default.svc.cluster.local
Address 2: 172.16.0.8 busybox-1.default-subdomain.default.svc.cluster.local
root@lhys:~# kubectl exec -it busybox1 -- nslookup busybox-2.default-subdomain
Server:    10.247.3.10
Address 1: 10.247.3.10 coredns.kube-system.svc.cluster.local

Name:      busybox-2.default-subdomain
Address 1: 172.16.0.9 busybox-2.default-subdomain.default.svc.cluster.local