上一篇文章 记录了K8s的DNS服务kube-dns搭建的过程，其中简略提到了一点就是kube-dns可以配置特定的域使用特定的DNS服务做解析。
相当于DNS中的NS记录，例如配置所有*.k8s.cn的解析都转发到169.169.0.3，下面是详细的配置。
搭建DNS
我选择使用dnsmasq在k8s中创建deploy，因为比较简单，在小型环境已经够用。我们使用ConfigMap写好dnsmasq的配置然后挂在pod上，DNS记录另外写一个文件。
注意不要用addn-hosts的方式写记录，经过测试这种方式会出现大量 dnsmasq[17]: Maximum number of concurrent DNS queries reached (max: 150) 并且解析缓慢
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| kind: ConfigMap
apiVersion: v1
metadata:
name: dnsmasq-cm
data:
dnsmasqconf: |-
resolv-file=/etc/resolv.conf
strict-order
cache-size=1024
listen-address=0.0.0.0
interface=eth0
conf-dir=/etc/dnsmasq.d
log-queries
records: |-
address=/wx.k8s.cn/192.168.21.55
address=/wx1.k8s.cn/192.168.21.56
address=/wx3.k8s.cn/192.168.21.11
---
apiVersion: apps/v1beta1 # for versions before 1.8.0 use apps/v1beta1
kind: Deployment
metadata:
name: dnsmasq-dep
labels:
app: dnsmasq
spec:
replicas: 1
selector:
matchLabels:
app: dnsmasq
template:
metadata:
labels:
app: dnsmasq
spec:
containers:
- name: dns
image: jpillora/dnsmasq
ports:
- containerPort: 53
protocol: TCP
- containerPort: 53
protocol: UDP
volumeMounts:
- mountPath: /etc/dnsmasq.conf
name: dnsconf
subPath: dnsmasq.conf
- mountPath: /etc/dnsmasq.d/records.conf
name: records
subPath: records.conf
volumes:
- name: dnsconf
configMap:
name: dnsmasq-cm
items:
- key: dnsmasqconf
path: dnsmasq.conf
- name: records
configMap:
name: dnsmasq-cm
items:
- key: records
path: records.conf
---
kind: Service
apiVersion: v1
metadata:
name: dns-node-k8s
spec:
clusterIP: 169.169.0.3
selector:
app: dnsmasq
ports:
- name: dnstcp
protocol: TCP
port: 53
targetPort: 53
- name: dnsudp
protocol: UDP
port: 53
targetPort: 53
|
创建好后应该可以使用nslookup测试一下
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| / # nslookup wx1.k8s.cn 169.169.0.3
Server: 169.169.0.3
Address 1: 169.169.0.3 dns-node-k8s.default.svc.wx-dev.local
Name: wx1.k8s.cn
Address 1: 192.168.21.56 bogon
|
修改kube-dns
可以直接edit ConfigMap文件
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| sudo kubectl edit cm -n kube-system kube-dns
|
加上stubDomains内容后等待几分钟kube-dns会自动刷新。
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| apiVersion: v1
data:
stubDomains: |
{"k8s.cn": ["169.169.0.3"]}
kind: ConfigMap
metadata:
labels:
addonmanager.kubernetes.io/mode: EnsureExists
name: kube-dns
namespace: kube-system
|
测试
直接使用nslookup测试，配置正确能解析出对应的ip
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| / # nslookup wx3.k8s.cn
Server: 169.169.0.2
Address 1: 169.169.0.2 kube-dns.kube-system.svc.wx-dev.local
Name: wx3.k8s.cn
Address 1: 192.168.21.11 bogon
|
