CoreDNS实现自定义域名解析

利源投资 發表於 2022-9-7 17:51:00

参考：https://support.huaweicloud.com/usermanual-cce/cce_01_0361.html
<h4>一、修改CoreDNS Hosts配置</h4>
修改CoreDNS配置文件，将自定义域名添加到hosts中。
例如将www.example.com指向192.168.1.1，通过CoreDNS解析www.example.com时，会返回192.168.1.1。
<div class="cnblogs_Highlighter">
<pre class="brush:csharp;gutter:true;">须知：
此处配置不能遗漏fallthrough字段，fallthrough表示当在hosts找不到要解析的域名时，会将解析任务传递给CoreDNS的下一个插件。如果不写fallthrough的话，任务就此结束，不会继续解析，会导致集群内部域名解析失败的情况。
hosts的详细配置请参见https://coredns.io/plugins/hosts/。</pre>
</div>
<div class="cnblogs_code">
<pre># kubectl edit configmap coredns -n kube-system
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
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
 }
 hosts {
 172.16.43.178 bx-cdh01
 172.16.43.187 bx-cdh02
 172.16.43.189 bx-cdh03
 172.16.43.192 bx-cdh04
 172.16.43.193 bx-cdh05
 172.16.43.177 cdh01
 172.16.43.199 cdh02
 172.16.43.184 cdh03
 172.16.43.182 cdh04
 172.16.43.159 cdh05
 fallthrough
 }
 prometheus :9153
 forward . /etc/resolv.conf
 cache 30
 loop
 reload
 loadbalance
}
kind: ConfigMap
metadata:
creationTimestamp: "2021-11-30T07:36:28Z"
managedFields:
- apiVersion: v1
fieldsType: FieldsV1
fieldsV1:
 f:data: {}
manager: kubeadm
operation: Update
time: "2021-11-30T07:36:28Z"
- apiVersion: v1
fieldsType: FieldsV1
fieldsV1:
 f:data:
 f:Corefile: {}
manager: Mozilla
operation: Update
time: "2022-09-07T07:11:00Z"
name: coredns
namespace: kube-system
resourceVersion: "112726088"
selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
uid: 218630e6-42f7-4e64-a0cf-cf97ac6bc6d6</pre>
</div>
在CoreDNS中修改hosts后，就不用单独在每个Pod中配置hosts了，带来了一定的方便性。　　
<h4>二、添加CoreDNS Rewrite配置指向域名到集群内服务</h4>
使用 CoreDNS 的 Rewrite 插件，将指定域名解析到某个 Service 的域名，相当于给Service取了个别名。
修改CoreDNS配置文件，将example.com指向default命名空间下的example服务。
<div class="cnblogs_code">
<pre>$ kubectl edit configmap coredns -n kube-system
apiVersion: v1
data:
Corefile: |-
.:5353 {
 bind {$POD_IP}
 cache 30
 errors
 health {$POD_IP}:8080
 kubernetes cluster.local in-addr.arpa ip6.arpa {
 pods insecure
 fallthrough in-addr.arpa ip6.arpa
 }
 rewrite name example.com example.default.svc.cluster.local
 loadbalance round_robin
 prometheus {$POD_IP}:9153
 forward . /etc/resolv.conf
 reload
}
kind: ConfigMap
metadata:
creationTimestamp: "2021-08-23T13:27:28Z"
labels:
app: coredns
k8s-app: coredns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: CoreDNS
release: cceaddon-coredns
name: coredns
namespace: kube-system
resourceVersion: "460"
selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
uid: be64aaad-1629-441f-8a40-a3efc0db9fa9　</pre>
</div>
<h4 id="section6" class="sectiontitle">三、使用CoreDNS级联自建DNS</h4>
修改CoreDNS配置文件，将forward后面的/etc/resolv.conf，改成外部DNS的地址
<div class="cnblogs_code">
<pre>$ kubectl edit configmap coredns -n kube-system
apiVersion: v1
data:
Corefile: |-
.:5353 {
 bind {$POD_IP}
 cache 30
 errors
 health {$POD_IP}:8080
 kubernetes cluster.local in-addr.arpa ip6.arpa {
 pods insecure
 fallthrough in-addr.arpa ip6.arpa
 }
 loadbalance round_robin
 prometheus {$POD_IP}:9153
 forward . 192.168.1.1
 reload
}
kind: ConfigMap
metadata:
creationTimestamp: "2021-08-23T13:27:28Z"
labels:
app: coredns
k8s-app: coredns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: CoreDNS
release: cceaddon-coredns
name: coredns
namespace: kube-system
resourceVersion: "460"
selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
uid: be64aaad-1629-441f-8a40-a3efc0db9fa9</pre>
</div>
 
　　 
来源：https://www.cnblogs.com/lina-2159/p/16666696.html

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CoreDNS实现自定义域名解析