cookie nginx lua redis não está configurando

este é nginx.conf

location /cookie {
    default_type "text/plain";
    lua_code_cache off;
    content_by_lua_file test.lua;
} 

este é o script de lua

local redis = require "redis"
local red = redis.connect('192.168.1.51',6379)

local ip = ngx.var.remote_addr
local secs = ngx.time()
local uid_key = ip .. secs
local uid = (uid_key)
local cookie = ngx.var.cookie_uid
local red_cookie = red:hget("cookie:"..uid, uid)


local args = ngx.req.get_headers()
local date_time = ngx.http_time(secs)

if cookie == nil or cookie ~= red_cookie then
    ngx.header['Set-Cookie'] = "path=/; uid=" .. uid 
    local res, err = red:hmset("cookie:".. uid,
    "uid", uid, "date_time", date_time,
    "user-agent", args["user-agent"])

    if not res then
        ngx.say("failed to set cookie: ", err)
    end 
end