我正在尝试使用lua+nginx+redis来设置cookie。我的思路是，如果cookie不存在，则设置cookie，然后保存到redis。

local redis = require "resty.redis"
local red = redis:new()
local md5 = require "md5"

local ip = ngx.var.remote_addr
local secs = ngx.time()
local uid_key = ip .. secs
local uid = md5.sumhexa(uid_key)
local cookie = ngx.var.cookie_uid
local red_cookie = red:hget("cookie:"..uid, uid)

local ok, err = red:connect("127.0.0.1", 6379)
if not ok then
    ngx.say("failed to connect to Redis: ", err)
    return
end

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

而我的nginx conf是

...

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

然而，我没有看到cookie被设置。我得到的错误是[error] 63519#0: * 408 after sending out response headers，客户端: 127.0.0.1，服务器: localhost，请求:“GET /cookie HTTP/1.1”，主机：“localhost”。

我似乎无法想出为什么这样不起作用？我也认为我可以纯粹地使用nginx设置cookie。我需要跟踪访问我的页面的用户。有什么想法吗？

谢谢！！

更新

我修改了我的想法，从上游访问点进行redis请求。现在我始终从redis.parser收到无效答复。

local redis = require "resty.redis"
local md5 = require "md5"
local parser = require "redis.parser"

local ip = ngx.var.remote_addr
local secs = ngx.time()
local uid_key = ip .. secs
local uid = md5.sumhexa(uid_key)

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

local test_cookie = ngx.location.capture("/redis_check_cookie", {args = {cookie_uid="cookie:"..uid}});
if test_cookie.status ~= 200 or not test_cookie.body then
    ngx.log(ngx.ERR, "failed to query redis")
    ngx.exit(500)
end

local reqs = {
    {"hmset", "cookie:"..uid, "path=/"}
}

local raw_reqs = {}
for i, req in ipairs(reqs) do
    table.insert(raw_reqs, parser.build_query(req))
end

local res = ngx.location.capture("/redis_set_cookie?" .. #reqs,
    { body = table.concat(raw_reqs, "")
    })

local replies = parser.parse_replies(res.body, #reqs)
for i, reply in ipairs(replies) do
    ngx.say(reply[1])
end

现在我的nginx conf包含：

upstream my_redis {
    server 127.0.0.1:6379;
    keepalive 1024 single;
}

和

    location /redis_check_cookie {
        internal;
        set_unescape_uri $cookie_uid $arg_cookie_uid;
        redis2_query hexists $cookie_uid uid;
        redis2_pass my_redis;
    }

    location /redis_set_cookie {
        internal;
        redis2_raw_queries $args $echo_request_body;
        redis2_pass my_redis;
    }