通过openresty 模块上传文件，并在上传的过程中进行md5计算

upload.lua

local upload = require "resty.upload"
local cjson = require "cjson"
local resty_md5 = require "resty.md5"


local chunk_size = 4096 -- should be set to 4096 or 8192
                     -- for real-world settings

local form = upload:new(chunk_size)
local data = ""

form:set_timeout(1000) -- 1 sec

local md5 = resty_md5:new()

if not md5 then
    ngx.say("failed to create md5 object")
    return
end

while true do
    local typ, res, err = form:read()
    if not typ then
        ngx.say("failed to read: ", err)
        return
    end

    if typ == "body" then
        local ok = md5:update(res)
        if not ok then
            ngx.say("failed to add data")
            return
        end
        ngx.say("read: ", cjson.encode({typ}))
    else
        ngx.say("read: ", cjson.encode({typ, res}))
    end

    if typ == "eof" then
        break
    end
end

local typ, res, err = form:read()
ngx.say("read: ", cjson.encode({typ, res}))

local digest = md5:final()

local str = require "resty.string"
ngx.say("md5: ", str.to_hex(digest))