今天有写过一个简单的基于nginx 的stream 代理dns server的服务，以下是集成coredns 的一个demo
同时也包含了consul 以及使用coredns 的rewrite 以及loadbalance 插件
环境准备
- docker-compose 文件
version: "3"
services:
lb:
image: openresty/openresty:alpine
networks:
service1_net:
ipv4_address: 192.168.1.2
volumes:
- "./nginx-lb.conf:/usr/local/openresty/nginx/conf/nginx.conf"
- "./dns.log:/var/log/nginx/dns.log"
ports:
- "53:53/udp"
- "80:80"
- "53:53/tcp"
consul:
image: consul
networks:
service1_net:
ipv4_address: 192.168.1.3
ports:
- "8500:8500"
coredns:
image: coredns/coredns:1.7.0
networks:
service1_net:
ipv4_address: 192.168.1.4
volumes:
- "./Corefile:/opt/Corefile"
command: -conf /opt/Corefile
networks:
service1_net:
ipam:
driver: default
config:
- subnet: 192.168.1.0/16
- 说明
为了估计consul dns 的地址，容器使用了固定ip - nginx 配置
worker_processes 1;
user root;
events {
worker_connections 1024;
}
# nginx dns server proxy
stream {
upstream dns_servers {
server 192.168.1.4:53;
}
server {
listen 53 udp;
listen 53; #tcp
proxy_pass dns_servers;
error_log /var/log/nginx/dns.log info;
}
}
http {
include mime.types;
default_type text/html;
gzip on;
resolver 127.0.0.1 ipv6=off valid=30s;
real_ip_header X-Forwarded-For;
real_ip_recursive on;
server {
listen 80;
charset utf-8;
default_type text/html;
# 基于nginx 代理的nginx 请求内容
location / {
index index.html;
default_type text/html;
set $kuaidi100 "www.kuaidi100.com";
proxy_pass https://$kuaidi100;
proxy_redirect off;
proxy_set_header Bloom-Request-Shard 1;
proxy_read_timeout 10000;
proxy_send_timeout 10000;
proxy_buffer_size 1M;
proxy_buffers 8 1M;
proxy_busy_buffers_size 1M;
proxy_temp_file_write_size 1M;
proxy_set_header Host $kuaidi100;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Host $server_name;
proxy_set_header X-Forwarded-Proto $scheme;
}
}
}
- coredns 配置
Corefile 文件
说明：
对于dalongrong.com 的dns 请求进行url 重写，将dns 请求重写consul 的service，同时修改answer ，对于dns 的查询全部转发到 consul dns server
dalongrong.com:53 {
log
health
rewrite stop {
name regex (.*)-(dc1).dalongrong.com {1}.service.{2}.consul
answer name (.*).service.(dc1).consul {1}-{2}.dalongrong.com
}
forward . 192.168.1.3:8600
}
.:53 {
log
health
cache 30
loadbalance round_robin
forward . 8.8.8.8 8.8.4.4 114.114.114.114
}
- 启动
注意需要先创建dns.log 文件
docker-compose u -d
集成使用
- 注册服务
curl -X PUT -d '{"ID": "openresty","Name": "openresty","Address": "192.168.1.2","Port": 80}' http://127.0.0.1:8500/v1/agent/service/register
- 查询请求
dig @127.0.0.1 openresty-dc1.dalongrong.com
效果 
说明
以上只是一个简单的学习使用，实际上我们如果我们集成了openresty，同时结合consul 的cname特性，可以方便的基于consul 的dns
功能进行动态反向代理，同时基于coredns 强大的plugin 能力，构建灵活的软件架构
参考资料
https://github.com/rongfengliang/nginx-coredns-consul-learning
https://coredns.io/plugins/
https://www.consul.io/api-docs/agent/service