nginx+lua+redis实现降级的示例代码

user nobody;
worker_processes  1;
events {
lua降级代码：/etc/nginx/lua/goods_list_advert.lua
 worker_connections  1024;
}
http {
 lua_package_path "/usr/share/lua/5.1/lua-resty-redis/lib/?.lua;;/usr/share/lua/5.1/lua-
resty-redis-cluster/lib/resty‘7/?.lua;;";
 lua_package_cpath "/usr/share/lua/5.1/lua-resty-redis-cluster/lib/libredis_slot.so;;";
 include    mime.types;
 default_type application/octet-stream;
 sendfile    on;
 keepalive_timeout  65;
 server {
   listen    80;
   server_name  127.0.0.1;
   server_name  192.168.232.100;
    #获取广告推荐数据
 location /goods_list_advert {
   default_type 'application/x-javascript;charset=utf-8';
     content_by_lua_file /etc/nginx/lua/goods_list_advert.lua;
   }
    #从服务层+mysql获取数据
   location /goods_list_advert_from_data {
     default_type 'application/x-javascript;charset=utf-8';
     content_by_lua '
       ngx.say("从服务层+mysql获取数据")
      ';
   }
 }
}

--获取get或post参数--------------------

local request_method = ngx.var.request_method
local args = nil
local param = nil
--获取参数的值
if "GET" == request_method then
    args = ngx.req.get_uri_args()
elseif "POST" == request_method then
    ngx.req.read_body()
    args = ngx.req.get_post_args()
end
sku_id = args["sku_id"]


--关闭redis的函数--------------------

local function close_redis(redis_instance)
    if not redis_instance then
        return
    end
    local ok,err = redis_instance:close();
    if not ok then
        ngx.say("close redis error : ",err);
    end
end


--连接redis--------------------

local redis = require("resty.redis");
--local redis = require "redis"
-- 创建一个redis对象实例。在失败，返回nil和描述错误的字符串的情况下
local redis_instance = redis:new();
--设置后续操作的超时（以毫秒为单位）保护，包括connect方法
redis_instance:set_timeout(1000)
--建立连接
local ip = '127.0.0.1'
local port = 6379
--尝试连接到redis服务器正在侦听的远程主机和端口
local ok,err = redis_instance:connect(ip,port)
if not ok then
    ngx.say("connect redis error : ",err)
    return close_redis(redis_instance);
end


--从redis里面读取开关--------------------

local key = "level_goods_list_advert"
local switch, err = redis_instance:get(key)
if not switch then
    ngx.say("get msg error : ", err)
    return close_redis(redis_instance)
end


--得到的开关为空处理--------------------

if switch == ngx.null then
    switch = "FROM_DATA"  --比如默认值
end


--当开关是要从服务中获取数据时--------------------
if "FROM_DATA" == switch then
    ngx.exec('/goods_list_advert_from_data');

--当开关是要从缓存中获取数据时--------------------
elseif "FROM_CACHE" == switch then

    local resp, err = redis_instance:get("nihao")
    ngx.say(resp)

--当开关是要从静态资源中获取数据时--------------------
elseif "FROM_STATIC" == switch then

    ngx.header.content_type="application/x-javascript;charset=utf-8"
    local file = "/etc/nginx/html/goods_list_advert.json"
    local f = io.open(file, "rb")
    local content = f:read("*all")
    f:close()
    ngx.print(content)

--当开关是要停掉数据获取时--------------------
elseif "SHUT_DOWN" == switch then

    ngx.say('no data')
end

[
{
“goods_id”:“1”,
“goods_name”:“测试1”,
},
{
“goods_id”:“2”,
“goods_name”:“测试2”,
}
]

--判断错误的响应，并进行计数， 后续便可以参考这个数值进行降级
if tonumber(ngx.var.status) == 200 then
  ngx.say(ngx.var.status)
  ngx.log(ngx.ERR,"upstream reponse status is " .. ngx.var.status .. ",please notice it")
  local error_count, err = redis_instance:get("error_count_goods_list_advert")
  --得到的数据为空处理
  if error_count == ngx.null then
    error_count = 0
  end
  error_count = error_count + 1
  --统计错误次数到error_count_goods_list_advert
  local resp,err = redis_instance:set("error_count_goods_list_advert",error_count)
  if not resp then
    ngx.say("set msg error : ",err)
    return close_redis(redis_instance)
  end
end