K8s 在所有使用的测试镜像上均无 DNS 解析

Question 1

无法通过评论发布那么多内容。以答案的形式发布。

我检查了导游您一直在参考并设置我自己的测试集群（GCP，3xDebian10 VM）。

不同之处在于，~/kube-cluster/master.yml我设置了不同的链接kube-flannel.yml（并且该文件的内容与指南中的文件不同：））

$ grep http master.yml 
      shell: kubectl apply -f  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml >> pod_network_setup.txt

在我的集群上：

$ kubectl get nodes
NAME         STATUS   ROLES    AGE     VERSION
instance-1   Ready    master   2m48s   v1.19.0
instance-2   Ready    <none>   38s     v1.19.0
instance-3   Ready    <none>   38s     v1.19.0

kubectl get pods -o wide -n kube-system
NAME                                 READY   STATUS    RESTARTS   AGE     IP            NODE         NOMINATED NODE   READINESS GATES
coredns-f9fd979d6-8sxg7              1/1     Running   0          4m48s   10.244.0.2    instance-1   <none>           <none>
coredns-f9fd979d6-z5gdl              1/1     Running   0          4m48s   10.244.0.3    instance-1   <none>           <none>

kube-flannel-ds-4khll                1/1     Running   0          2m58s   10.156.0.21   instance-3   <none>           <none>
kube-flannel-ds-h8d9l                1/1     Running   0          2m58s   10.156.0.20   instance-2   <none>           <none>
kube-flannel-ds-zhzbf                1/1     Running   0          4m49s   10.156.0.19   instance-1   <none>           <none>

$ kubectl -n kube-system get svc -o wide
NAME       TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE     SELECTOR
kube-dns   ClusterIP   10.96.0.10   <none>        53/UDP,53/TCP,9153/TCP   6m15s   k8s-app=kube-dns

sammy@instance-1:~$ ip route
default via 10.156.0.1 dev ens4 
10.156.0.1 dev ens4 scope link 
10.244.0.0/24 dev cni0 proto kernel scope link src 10.244.0.1 
10.244.1.0/24 via 10.244.1.0 dev flannel.1 onlink 
10.244.2.0/24 via 10.244.2.0 dev flannel.1 onlink 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown

我没有发现 DNS 延迟问题。

kubectl create deployment busybox --image=nkolchenko/enea:server_go_latest
deployment.apps/busybox created

sammy@instance-1:~$ time kubectl exec -it busybox-6f744547bf-hkxnk -- nslookup default.default
Server:         10.96.0.10
Address:        10.96.0.10:53

** server can't find default.default: NXDOMAIN

** server can't find default.default: NXDOMAIN

command terminated with exit code 1

real    0m0.227s
user    0m0.106s
sys     0m0.012s


sammy@instance-1:~$ time kubectl exec -it busybox-6f744547bf-hkxnk -- nslookup google.com
Server:         10.96.0.10
Address:        10.96.0.10:53

Non-authoritative answer:
Name:   google.com
Address: 172.217.22.78

Non-authoritative answer:
Name:   google.com
Address: 2a00:1450:4001:820::200e


real    0m0.223s
user    0m0.102s
sys     0m0.012s

如果您需要我运行任何其他测试，请告诉我，我会在整个周末保留这个集群，然后将其拆除。

更新：

$ cat ololo 
apiVersion: v1
kind: Pod
metadata:
  name: dnsutils
  namespace: default
spec:
  containers:
  - name: dnsutils
    image: gcr.io/kubernetes-e2e-test-images/dnsutils:1.3
    command:
      - sleep
      - "3600"
    imagePullPolicy: IfNotPresent
  restartPolicy: Always

$ kubectl create -f ololo 
pod/dnsutils created


$ kubectl get -A all  -o wide | grep dns
default       pod/dnsutils                             1/1     Running   0          63s     10.244.2.8    instance-2   <none>           <none>
kube-system   pod/coredns-cc8845745-jtvlh              1/1     Running   0          10m     10.244.1.3    instance-3   <none>           <none>
kube-system   pod/coredns-cc8845745-xxh28              1/1     Running   0          10m     10.244.0.4    instance-1   <none>           <none>
kube-system   pod/coredns-cc8845745-zlv84              1/1     Running   0          10m     10.244.2.6    instance-2   <none>           <none>

instance-1:~$ kubectl exec -i -t dnsutils -- time nslookup google.com
Server:         10.96.0.10
Address:        10.96.0.10#53

Name:   google.com
Address: 172.217.21.206
Name:   google.com
Address: 2a00:1450:4001:818::200e

real    0m 0.01s
user    0m 0.00s
sys     0m 0.00s

Answer