K8s容器内没有互联网连接

Question

我在虚拟机中安装了一个干净的K8s集群(Debian 10)。在安装和集成到我的景观之后，我检查了测试高寒图像中的连接性。结果，coreDNS日志中传出通信量的连接不起作用，也没有任何信息。我使用构建映像的解决方案来覆盖/etc/ used并替换DNS条目(例如，将1.1.1.1设置为Nameserver)。在那次短暂的“黑客攻击”之后，与互联网的连接完美地运作起来。但这不是一个长期的解决方案，我想使用官方的方法。在K8s coreDNS的文档中，我找到了forward部分，并像选项一样解释标志，将查询转发到预定义的本地解析器。我认为转发到本地resolv.conf和解决过程不正确。有人能帮我解决这个问题吗？

基本设置：

• K8s版本: 1.19.0
• K8s安装:1主+2工作节点
• 基于: Debian 10 VM的
• CNI:法兰绒

F 211

状态的CoreDNS Pods

kube-system            coredns-xxxx 1/1     Running   1          26h
kube-system            coredns-yyyy 1/1     Running   1          26h

CoreDNS日志：

.:53
[INFO] plugin/reload: Running configuration MD5 = 4e235fcc3696966e76816bcd9034ebc7
CoreDNS-1.6.7

CoreDNS config:

apiVersion: v1
data:
  Corefile: |
    .:53 {
        errors
        health {
           lameduck 5s
        }
        ready
        kubernetes cluster.local in-addr.arpa ip6.arpa {
           pods insecure
           fallthrough in-addr.arpa ip6.arpa
           ttl 30
        }
        prometheus :9153
        forward . /etc/resolv.conf
        cache 30
        loop
        reload
        loadbalance
    }
kind: ConfigMap
metadata:
  creationTimestamp: ""
  name: coredns
  namespace: kube-system
  resourceVersion: "219"
  selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
  uid: xxx

输出高寒图：

/ # nslookup -debug google.de
;; connection timed out; no servers could be reached

豆荚输出resolv.conf

/ # cat /etc/resolv.conf 
nameserver 10.96.0.10
search development.svc.cluster.local svc.cluster.local cluster.local invalid
options ndots:5

主机输出resolv.conf

cat /etc/resolv.conf 
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 213.136.95.11
nameserver 213.136.95.10
search invalid

主机/run/flannel/subnet.env的输出

cat /run/flannel/subnet.env
FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.0.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

kubectl get pods -n kube-system -o wide的输出

coredns-54694b8f47-4sm4t                 1/1     Running   0          14d   10.244.1.48    xxx3-node-1   <none>           <none>
coredns-54694b8f47-6c7zh                 1/1     Running   0          14d   10.244.0.43    xxx2-master   <none>           <none>
coredns-54694b8f47-lcthf                 1/1     Running   0          14d   10.244.2.88    xxx4-node-2   <none>           <none>
etcd-xxx2-master                      1/1     Running   7          27d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>
kube-apiserver-xxx2-master            1/1     Running   7          27d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>
kube-controller-manager-xxx2-master   1/1     Running   7          27d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>
kube-flannel-ds-amd64-4w8zl              1/1     Running   8          28d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>
kube-flannel-ds-amd64-w7m44              1/1     Running   7          28d   xxx.xx.xx.xxx   xxx3-node-1   <none>           <none>
kube-flannel-ds-amd64-xztqm              1/1     Running   6          28d   xxx.xx.xx.xxx   xxx4-node-2   <none>           <none>
kube-proxy-dfs85                         1/1     Running   4          28d   xxx.xx.xx.xxx   xxx4-node-2   <none>           <none>
kube-proxy-m4hl2                         1/1     Running   4          28d   xxx.xx.xx.xxx   xxx3-node-1   <none>           <none>
kube-proxy-s7p4s                         1/1     Running   8          28d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>
kube-scheduler-xxx2-master            1/1     Running   7          27d   xxx.xx.xx.xxx   xxx2-master   <none>           <none>

Answer 1

问题：

(两个) coreDNS荚仅部署在主节点上。您可以使用此命令检查设置。

kubectl get pods -n kube-system -o wide | grep coredns

解决方案：

我可以通过扩展coreDNS吊舱和编辑部署配置来解决这个问题。必须执行下列命令。

1. kubectl edit deployment coredns -n kube-system
2. Set replicas value to node quantity e.g. 3
3. kubectl patch deployment coredns -n kube-system -p "{\"spec\":{\"template\":{\"metadata\":{\"annotations\":{\"force-update/updated-at\":\"$(date +%s)\"}}}}}"
4. kubectl get pods -n kube-system -o wide | grep coredns

源

• https://blog.dbi-services.com/kubernetes-dns-resolution-using-coredns-force-update-deployment/

提示

如果您的coreDNS仍然有问题，并且您的DNS解析偶尔起作用，那么请看一下这个post。