运维开发网

coreDNS域名无法解析问题

运维开发网 https://www.qedev.com 2020-04-01 13:39 出处:网络 作者:运维开发网整理
问题: 在pod内无法解析域名 解决: busybox的镜像有bug,导致ping可以解析,但是nslookup无法解析 kubectl run -it --rm --image=infoblox/dnstools dns-client 换成上面的就可以,实在解决不了再看下面的 dnstools# nslookup kubernetes 方式一: 创建coredns.ya
问题: 在pod内无法解析域名


解决:

busybox的镜像有bug,导致ping可以解析,但是nslookup无法解析

kubectl run -it --rm --image=infoblox/dnstools dns-client


换成上面的就可以,实在解决不了再看下面的


dnstools# nslookup kubernetes




方式一:

创建coredns.yaml  要用hostwork模式,hostwork就是用的宿主机的 服务器IP端口

cluster-dns 指定成宿主机的

然后重启kubelet

然后重新创建pod

修改/etc/resolv.conf






[[email protected] kubernetes]# kubectl get po -o wide -n kube-system
NAME                       READY     STATUS    RESTARTS   AGE       IP           NODE
coredns-6d9f9c4fc9-2h652   1/1       Running   0          1h        10.1.1.111   10.1.1.111
coredns-6d9f9c4fc9-6prhs   1/1       Running   0          1h        10.1.1.68    10.1.1.68


修改三台的 宿主机的 resolv.conf   都改成 10.1.1.111
[[email protected] kubernetes]# cat /etc/resolv.conf 
# Generated by NetworkManager
search openstacklocal
nameserver 10.1.1.111


修改三台的,改成各自对应的宿主机的ip地址
[[email protected] kubernetes]# cat kubelet
KUBELET_HOSTNAME="--hostname-override=10.1.1.68"
KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=registry.cn-hangzhou.aliyuncs.com/google_containers/pause-amd64:3.1"
KUBELET_CONFIG="--config=/etc/kubernetes/kubelet-config.yml"
KUBELET_ARGS="--bootstrap-kubeconfig=/etc/kubernetes/kubelet-bootstrap.conf --kubeconfig=/etc/kubernetes/kubelet.conf --cert-dir=/etc/kubernetes/pki --network-plugin=cni --cni-bin-dir=/opt/cni/bin --cni-conf-dir=/etc/cni/net.d --cluster-dns=10.1.1.68 --cluster-domain=cluster.local "



在cul容器内部访问
[ [email protected]-87b54756-tsnwd:/ ]$ curl example-service.default.svc.cluster.local
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>



在外部主机访问
[[email protected] kubernetes]# curl example-service.default.svc.cluster.local
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>





但是访问下面短的 还是不行
[[email protected] kubernetes]# curl example-service  
curl: (6) Could not resolve host: example-service; Unknown error

解决办法,指点:搜索域有问题,
他的是搜索域的问题







在busybox里面可以访问短的域名

[[email protected] kubernetes]# kubectl run -it --rm --image=infoblox/dnstools dns-client
If you don‘t see a command prompt, try pressing enter.
dnstools# 
dnstools# 
dnstools# curl example-service 
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>




方式二:

新版本自然解决:

流程:

1、删除原先coredns的配置

2、部署coredns

3. 删除原先的pod、service、重新创建,



#!/bin/bash
wget https://raw.githubusercontent.com/coredns/deployment/master/kubernetes/coredns.yaml.sed
wget https://raw.githubusercontent.com/coredns/deployment/master/kubernetes/deploy.sh
chmod +x deploy.sh
./deploy.sh -i 10.96.0.10 -d cluster.local. > dns.yaml
kubectl apply -f dns.yaml;


--cluster-dns=10.1.1.8 --cluster-domain=cluster.local"



在外边访问service ,那是另外一个问题了啊!但是首先你cluster 中 DNS的IP 不应拿hostip 来顶住哦

可以把内部的cluster ip 再用其他的代理 代理出来,里边的还是用 一个clusterip


#!/bin/bash
export http_proxy=
export https_proxy=
wget https://raw.githubusercontent.com/coredns/deployment/master/kubernetes/coredns.yaml.sed
wget https://raw.githubusercontent.com/coredns/deployment/master/kubernetes/deploy.sh
chmod +x deploy.sh
./deploy.sh -i 10.254.0.2 -d cluster.local. > dns.yaml
kubectl apply -f dns.yaml;
16:30:50




[[email protected] kubernetes]# netstat -anp |grep 53
tcp        0      0 10.1.1.111:10250        10.1.1.8:53506          ESTABLISHED 32337/kubelet       
tcp6       0      0 :::53                   :::*                    LISTEN      25791/coredns       
tcp6       0      0 :::9153                 :::*                    LISTEN      25791/coredns       
udp6       0      0 :::53                   :::*                                25791/coredns       
unix  2      [ ACC ]     STREAM     LISTENING     15097    653/NetworkManager   /var/run/NetworkManager/private-dhcp
unix  3      [ ]         STREAM     CONNECTED     20544    653/NetworkManager   
unix  2      [ ]         DGRAM                    15853    508/systemd-udevd    
unix  2      [ ]         DGRAM                    20239    653/NetworkManager   
unix  3      [ ]         STREAM     CONNECTED     20979    653/NetworkManager   
unix  3      [ ]         STREAM     CONNECTED     20983    653/NetworkManager  




[ [email protected]-87b54756-782kr:/ ]$ nslookup example-service
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      example-service
Address 1: 10.104.125.95 example-service.default.svc.cluster.local
[ [email protected]-87b54756-782kr:/ ]$ curl example-service
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
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