如何在nginx.conf中初始化mysql以便在lua中使用openresty

http {
    lua_shared_dict mysql 100m;
    init_by_lua_block {
        local mysql = require "resty.mysql"
        local db, err = mysql:new()
        if not db then
            ngx.log(ngx.ERR, "failed to instantiate mysql: ", err)
            return
        end
        db:set_timeout(1000) -- 设置超时时间

        local ok, err, errno, sqlstate = db:connect{
            host = "localhost", -- MySQL主机地址
            port = 3306, -- MySQL端口
            database = "your_database", -- 数据库名称
            user = "your_username", -- 用户名
            password = "your_password", -- 密码
            charset = "utf8", -- 字符集
            max_packet_size = 1024 * 1024, -- 最大数据包大小
        }

        if not ok then
            ngx.log(ngx.ERR, "failed to connect: ", err, ": ", errno, " ", sqlstate)
            return
        end

        -- 将数据库连接对象保存到全局变量中，以便在Lua中使用
        ngx.ctx.mysql = db
    }
}