技术要求很简明：
nginx分发请求的时候，upstream是由lua从redis中读取配置动态生成的，这样便于用程序动态修改。
装好nginx+lua，过程不表。 把lua redis的模块配到路径中
1wget https://raw.github.com/nrk/redis-lua/version-2.0/src/redis.lua
nginx配置如下：
1server {
2 listen 80;
3 server_name _;
4 server_name_in_redirect off;
5 port_in_redirect off;
6 root /root/html;
7
8 location / {
9 set $upstream "";
10 rewrite_by_lua '
11 -- load global route cache into current request scope
12 -- by default vars are not shared between requests
13 local routes = _G.routes
14
15 -- setup routes cache if empty
16 if routes == nil then
17 routes = {}
18 ngx.log(ngx.ALERT, "Route cache is empty.")
19 end
20
21 -- try cached route first
22 local route = routes[ngx.var.http_host]
23 if route == nil then
24 local redis = require "redis"
25 local client = redis.connect("localhost", 6379)
26 route = client:get(ngx.var.http_host)
27 end
28
29 -- fallback to redis for lookups
30 if route ~= nil then
31 ngx.var.upstream = route
32 routes[ngx.var.http_host] = route
33 _G.routes = routes
34 else
35 ngx.exit(ngx.HTTP_NOT_FOUND)
36 end
37 ';
38
39 proxy_buffering off;
40 proxy_set_header Host $host;
41 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
42 proxy_redirect off;
43 proxy_connect_timeout 10;
44 proxy_send_timeout 30;
45 proxy_read_timeout 30;
46 proxy_pass http://$upstream;
47 }
48}
送进redis一些数据
1redis-cli =>
2SET localhost 127.0.0.1:49153
测试一下：
1curl -i -X HEAD "http://127.0.0.1/" # -> 404，没这个域名
2curl -i -X HEAD "http://localhost/" # -> 正常
