一，背景
因爲k8s集羣以及web服務測試，每次使用/etc/hosts配置或者寫ip都不太好，所以決定搭建dns服務器做域名解析，後期可以做k8s-kube-dns的父dns服務器。
二，搭建
1. 服務器
dnsserver 192.168.89.128
2. 安裝dns軟件包
yum -y install bind bind-chroot bind-utils
3. 修改dns配置
vim /etc/named.conf
options {
/*此處改成any*/
listen-on port 53 { any; };
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
recursing-file "/var/named/data/named.recursing";
secroots-file "/var/named/data/named.secroots";
/*此處改成any*/
allow-query { any; };
recursion yes;
dnssec-enable yes;
dnssec-validation yes;
/* Path to ISC DLV key */
bindkeys-file "/etc/named.root.key";
managed-keys-directory "/var/named/dynamic";
pid-file "/run/named/named.pid";
session-keyfile "/run/named/session.key";
};
logging {
channel default_debug {
file "data/named.run";
severity dynamic;
};
};
zone "." IN {
type hint;
file "named.ca";
};
/*此zone做測試域名解析使用*/
zone "ktz.com" IN {
type master;
file "ktz.com.zone";
};
/*此zone做web網站域名解析使用*/
zone "web.com" IN {
type master;
file "web.com.zone";
};
/*此zone做k8s集羣域名解析使用*/
zone "k8s.com" IN {
type master;
file "k8s.com.zone";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
cp -a /var/named/named.localhost /var/named/ktz.com.zone
cp -a /var/named/named.localhost /var/named/web.com.zone
cp -a /var/named/named.localhost /var/named/k8s.com.zone
$TTL 1D
@ IN SOA @ k8s.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS @
A 192.168.89.132
k8smaster A 192.168.89.132
k8snode01 A 192.168.89.133
k8snode02 A 192.168.89.134
4. 重啓並開機自啓，配置/etc/resolv.conf
systemctl restart named
systemctl enabled named
vim /etc/resolv.conf(修改相關服務器dns)
nameserver 192.168.89.128
5. 測試驗證
k8smaster:
yum -y install bind-utils(提供nslookup命令做域名解析)
nslookup k8snode01.k8s.com
Server: 192.168.89.128
Address: 192.168.89.128#53
Name: k8snode01.k8s.com
Address: 192.168.89.133
可以正確的解析到對應的服務器，操作完成
三， 啓動k8s集羣服務/kube-dns，並關聯本地dns服務器
1. 啓動k8s集羣服務, 並查看狀態
k8smaster
systemctl restart docker kube-controller-manager kube-scheduler kube-apiserver
k8snode01
systemctl restart docker flanneld kubelet kube-proxy
k8snode02
systemctl restart docker flanneld kubelet kube-proxy
k8smaster
kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
kube-dns-85bdb85857-bjvbf 3/3 Running 0 43s
kube-dns服務仍然在正常運行
2. 將kube-dns與本地dns服務器關聯
1). 測試一下kube-dns
kubectl run busybox --image=192.168.89.132:5000/busybox --command -- sleep 3600
deployment.apps/busybox created
kubectl get pods
NAME READY STATUS RESTARTS AGE
busybox-54584f87db-4prnh 1/1 Running 0 23s
kubectl get svc
mysql-service NodePort 169.169.188.11 <none> 3306:64298/TCP 12d
kubectl exec -it busybox-54584f87db-4prnh -- nslookup mysql-service
Server: 169.169.0.10
Address: 169.169.0.10:53
Name: mysql-service.default.svc.k8s.com
Address: 169.169.188.11
*** Can't find mysql-service.svc.k8s.com: No answer
*** Can't find mysql-service.k8s.com: No answer
*** Can't find mysql-service.localdomain: No answer
*** Can't find mysql-service.default.svc.k8s.com: No answer
*** Can't find mysql-service.svc.k8s.com: No answer
*** Can't find mysql-service.k8s.com: No answer
*** Can't find mysql-service.localdomain: No answer
kubectl exec busybox-54584f87db-4prnh -- ping kubernetes.default.svc.k8s.com
PING kubernetes.default.svc.k8s.com (169.169.0.1): 56 data bytes
64 bytes from 169.169.0.1: seq=0 ttl=64 time=0.028 ms
kubectl exec -it busybox-54584f87db-4prnh /bin/sh
cat /etc/resolv.conf
nameserver 169.169.0.10
search default.svc.k8s.com svc.k8s.com k8s.com localdomain
options ndots:5
可知集羣dns的ip地址未169.169.0.10
ping www.baidu.com
PING www.baidu.com (112.80.248.75): 56 data bytes
64 bytes from 112.80.248.75: seq=0 ttl=127 time=2.616 ms
ping k8smaster.k8s.com
ping: bad address 'k8smaster.k8s.com'
ping公網的可以，ping本地的一個服務不行，則需要關聯本地dns
2). 將本地dns服務器配置成kube-dns上游dns服務器
a. 修改 kube-dns.yaml文件中ConfigMap部分, 添加了data部分
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
# 配置上游dns服務器
upstreamNameservers: |
["192.168.89.128"]
b. 刪除之前的kube-dns，重新創建
kubectl delete -f kube-dns.yaml
kubectl get pods -n kube-system
kubectl create -f kube-dns.yaml
kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
kube-dns-85bdb85857-z62nj 3/3 Running 0 9s
c. 驗證
kubectl exec -it busybox-54584f87db-d97qk /bin/sh
ping k8smaster.web.com 無效 ，可以說明配置上游dns服務器無效。
繼續修改kube-dns.yaml
vim kube-dns.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
stubDomains: |
{"web.com": ["192.168.89.128"]}
---
kubectl exec -it busybox-54584f87db-d97qk /bin/sh
ping todolist.web.com
PING todolist.web.com (192.168.89.132): 56 data bytes
64 bytes from 192.168.89.132: seq=0 ttl=63 time=0.234 ms
可以ping通，測試通過，可以和k8s集羣外的本地服務通信了
四， 總結
使用本地域名前綴ktz.com進行驗證
vim /var/named/ktz.com.zone
$TTL 1D
@ IN SOA @ ktz.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS @
A 192.168.89.133
www A 192.168.89.133
systemctl restart named
kubectl exec -it busybox-54584f87db-d97qk /bin/sh
ping www.ktz.com
PING www.ktz.com (192.168.89.133): 56 data bytes
64 bytes from 192.168.89.133: seq=0 ttl=64 time=0.037 ms
當本地再新加服務，需要域名解析，且服務不在k8s集羣中，但是集羣中要使用時，則只需要配置本地域名解析即可。
雲計算之kubernetes系列——配置本地dns服務並關聯kube-dns
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