【发布时间】：2021-06-29 11:54:08
【问题描述】：
我的 K8 DNS 没有解析，因此我确实按照mentioned here 的调试步骤进行操作。由于我是 K8 的新手，有人可以指出我面临的问题吗？我无法从调试步骤中提取任何有用的信息。
cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.2 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.2 LTS"
kubectl 版本
Client Version: version.Info{Major:"1", Minor:"20",
GitVersion:"v1.20.5", GitCommit:"6b1d87acf3c8253c123756b9e61dac642678305f", GitTreeState:"clean", BuildDate:"2021-03-18T01:10:43Z", GoVersion:"go1.15.8", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"20", GitVersion:"v1.20.5", GitCommit:"6b1d87acf3c8253c123756b9e61dac642678305f", GitTreeState:"clean", BuildDate:"2021-03-18T01:02:01Z", GoVersion:"go1.15.8", Compiler:"gc", Platform:"linux/amd64"}
kubectl 获取命名空间
NAME STATUS AGE
default Active 7d4h
kubectl 获取 pod dnsutils
NAME READY STATUS RESTARTS AGE
dnsutils 1/1 Running 18 18h
kubectl exec -i -t dnsutils -- nslookup kubernetes.default
;; connection timed out; no servers could be reached
kubectl exec -ti dnsutils -- cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local
cluster.local
options ndots:5
kubectl 获取 pod --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS
AGE
coredns-74ff55c5b-6vsml 1/1 Running 12 7d4h
coredns-74ff55c5b-mww7g 1/1 Running 12 7d4h
kubectl 日志 --namespace=kube-system -l k8s-app=kube-dns
.:53
[INFO] plugin/reload: Running configuration MD5 = db32ca3650231d74073ff4cf814959a7
CoreDNS-1.7.0
linux/amd64, go1.14.4, f59c03d
[INFO] Reloading
[INFO] plugin/health: Going into lameduck mode for 5s
[INFO] plugin/reload: Running configuration MD5 = 3d3f6363f05ccd60e0f885f0eca6c5ff
[INFO] Reloading complete
[INFO] 10.244.0.1:16732 - 59651 "HINFO IN 6307445054232439722.7934820194057826263. udp 57 false 512" NXDOMAIN qr,rd,ra 132 0.006053527s
[INFO] 127.0.0.1:58672 - 59651 "HINFO IN 6307445054232439722.7934820194057826263. udp 57 false 512" NXDOMAIN qr,rd,ra 132 0.00658948s
[INFO] plugin/reload: Running configuration MD5 = db32ca3650231d74073ff4cf814959a7
CoreDNS-1.7.0
linux/amd64, go1.14.4, f59c03d
[INFO] Reloading
[INFO] plugin/health: Going into lameduck mode for 5s
[INFO] plugin/reload: Running configuration MD5 = 3d3f6363f05ccd60e0f885f0eca6c5ff
[INFO] Reloading complete
[INFO] 10.244.0.62:56364 - 32900 "HINFO IN 2808379183970575835.6786373795048579500. udp 57 false 512" NXDOMAIN qr,rd,ra 132 0.004922932s
[INFO] 127.0.0.1:48277 - 32900 "HINFO IN 2808379183970575835.6786373795048579500. udp 57 false 512" NXDOMAIN qr,rd,ra 132 0.007889024s
[INFO] 10.244.0.62:49106 - 59651 "HINFO IN 6307445054232439722.7934820194057826263. udp 57 false 512" NXDOMAIN qr,rd,ra 132 0.005058199s
kubectl get svc --namespace=kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 7d4h
monitoring-influxdb ClusterIP 10.102.51.183 <none> 8086/TCP 4d21h
kubectl 获取端点 kube-dns --namespace=kube-system
NAME ENDPOINTS AGE
kube-dns 10.244.0.45:53,10.244.0.47:53,10.244.0.45:53 + 3 more... 7d4h
cat /run/systemd/resolve/resolv.conf
nameserver 8.8.8.8
nameserver 2001:4860:4860::8888
cat /etc/systemd/resolved.conf
[Resolve]
DNS=8.8.8.8 2001:4860:4860::8888
cat /etc/resolv.conf
nameserver 127.0.0.53
options edns0 trust-ad
这有点奇怪，两个 resolv.conf 有不同的值。另外，我不知道选择哪个 IP（如果我必须手动设置 DNS IP）。
kubeadm 配置视图
apiServer:
extraArgs:
authorization-mode: Node,RBAC
timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
type: CoreDNS
etcd:
local:
dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: v1.20.5
networking:
dnsDomain: cluster.local
podSubnet: 10.244.0.0/16
serviceSubnet: 10.96.0.0/12
scheduler: {}
更新
dnsutils 分配的 pod 的 IP 是 10.244.2.20，无法从单个 k8 主节点访问。
ping 10.244.2.20
【问题讨论】：
-
你安装CNI插件了吗？你的节点 cidr/子网是什么？
-
cidr/subnet
10.244.0.0/16和法兰绒/印花布用于 CNI。我确实清除并删除了所有节点，重新加入它们，然后它就像一个魅力。我想我对防火墙规则搞砸了太多。稍后会详细记录。
标签： kubernetes dns