Openresty 进行路由系统设计

1、系统基础设计图为：

用户通过Http访问Openresty（Nginx + Lua）， 其中Nginx虚拟主机中配置文件进行Lua脚本加载。

LUA通过nginx内置变量或者http请求中变量来区分不同集群，使用LUA脚本从redis中获取所属集群。

然后通过反向代理到对应集群。

2、 Openresty配置

Nginx主配置文件：

 user nginx;
 worker_processes  ;
 pid        logs/nginx.pid;

 worker_rlimit_nofile ;

 events {
     use epoll;
     worker_connections  ;
 }

 http {
     lua_package_path "/usr/local/openresty/lualib/resty/lrucache/?.lua;;";   # 加载lua自定义模块。
     include       mime.types;
     default_type  application/octet-stream;
     log_format  main  '$remote_addr - $remote_user [$time_local] $request $http_host '
                       '$status $body_bytes_sent $http_referer '
                       '"$http_user_agent" $http_x_forwarded_for '
                       '$upstream_addr $upstream_status $upstream_cache_status '
               '$upstream_response_time $request_time';
     access_log logs/access.log main;
     error_log logs/error.log;
     sendfile        on;
     tcp_nopush     on;
     max_ranges  ;
     keepalive_timeout  ;
     gzip  on;
     gzip_min_length 1k;
     gzip_buffers  16k;
     gzip_comp_level ;
     gzip_types application/x-www-form-urlencoded application/pdf text/plain application/x-javascript application/javascript text/css application/xml application/json;
     client_max_body_size 22m;
     client_body_buffer_size  1024k;
     client_header_buffer_size  1024k;
     underscores_in_headers on;

         location /status {
             stub_status on;
             access_log off;
             allow 127.0.0.1;
             deny all;
         }
     }
     include /data/work/conf/conf.d/*/*.conf;

虚拟主机的配置：

 server {
     listen ;
     server_name 域名;
     access_log  logs/access_80.log main;
     error_log  logs/error_80.log;

     location / {
     resolver DNS的IP地址 valid=;   如果配置文件中使用了域名，需要此配置，不然无法解析DNS。
         set $url '';  定义变量
         set $upstream_port '';  变量赋值
         rewrite_by_lua_file lua/get_upstream_url.lua;   加载lua脚本
     proxy_pass http://$url$request_uri;
     proxy_http_version 1.1;
     proxy_set_header Upgrade $http_upgrade;
     proxy_set_header connection "keep-alive";
     proxy_set_header Host $host;
     proxy_set_header X-Forwarded-Port $server_port;
     proxy_set_header X-Forwarded-For $remote_addr;     proxy_set_header X-Real-IP $remote_addr;
     proxy_read_timeout ;
     proxy_send_timeout ;
     proxy_connect_timeout ;
     proxy_temp_file_write_size 10240k;
     }
 }

lua 脚本

local localCache = require("mycache")  本地缓存配置
local localRes, err = localCache.get(ngx.var.host)
if localRes ~= nil then
    ngx.var.url = localRes .. ":" .. ngx.var.upstream_port
    return
else
    local redis = require "resty.redis"
    local red = redis:new()
    red:set_timeout()
    local ok, err = red:connect("redis地址", )
    if not ok then
        ngx.log(ngx.ERR, "failed to connect: ", err)
        return
    end
    local res, err = red:hget("hosts", ngx.var.host)
    if not res then
        ngx.log(ngx.ERR, "failed to get host: ", err)
        return
    end
    if res == ngx.null then
        ngx.log(ngx.ERR, "host not found.")
        ngx.var.url = "异常网址"
           return
    else
        localCache.set(ngx.var.host, res)
        ngx.var.url = res .. ":" .. ngx.var.upstream_port
    end
    local ok, err = red:set_keepalive(, )
    if not ok then
       ngx.log(ngx.ERR, "failed to set keepalive: ", err)
       return
    end
end

自定义本地缓存的lua模块脚本

 local _M = {}

 local lrucache = require "resty.lrucache"

 local c, err = lrucache.new()
 if not c then
     return error("failed to create the cache: " .. (err or "unknown"))
 end

 function _M.get(host)
     local key = c:get(host)
     return key
 end

 function _M.set(host, key)
     c:set(host, key, )
     local res = c:get(host)
 end

 return _M