Simple file uploading service based on Lua-resty-upload

Today I learned about the Lua-resty-upload module, and based on the Lua-resty-upload module simple implementation of a basic form file upload service.

Lua-resty-upload's project address on GitHub is: https://github.com/openresty/lua-resty-upload

From the implementation can be seen, in fact, the implementation of upload service is relatively simple, a source file Lualib/resty/upload.lua, the total number of lines of code is only 300 lines.

Below I have organized the process of building a file upload service:

1, the front page is very simple, is to use the form of input file to trigger the file upload, the code is as follows:

<!--myupload.html--><! DOCTYPE html>

The corresponding myupload.html file is deployed under openresty/nginx/html/.

2, implement the LUA code to receive the file Upload form information and save to the local path, the code is as follows:

-- myupload.lua--==========================================--  File Upload--================================ ==========local upload = require  "Resty.upload" local cjson = require  " Cjson "Local chunk_size = 4096local form, err = upload:new (chunk_size) if  not form then    ngx.log (NGX. err,  "failed to new upload: ",  err)     ngx.exit (NGX. Http_internal_server_error) Endform:set_timeout (-- ) string  split  split string.split =  function (s, p)     local rt= {}    string.gsub (s,  ' [^ ' ... P.. ') + ',  function (w)  table.insert (rt, w)  end )     return rtend--   supports strings before and after  trimstring.trim = function (s)     return  (S:gsub ("^%s* (.- %s*$ ", "%1 ")) end--  file saved root path Local saverootpath =  "/home/steven/openresty/nginx/upload/"--  saved file object local filetosave--file is saved successfully local  Ret_save = falsewhile true do    local typ, res, err  = form:read ()     if not typ then         ngx.say ("failed to read: ",  err)          return    end    if typ ==  "Header"   then        --  start reading  http header         --  parse out the file name of this upload         local key  = res[1]        local value = res[2]         if key ==  "Content-disposition"  then             --  parse out the file name of this upload              -- form-data; name= "Testfilename";  filename= "Testfile.txt"              local kvlist = string.split (value,  '; ')             for _, kv in  Ipairs (kvlist)  do                 local seg = string.trim (KV)                  if seg:find ("filename")  then                     local kvfile  = string.split (seg,  "=")                  &nbSp;   local filename = string.sub (kvfile[2], 2, -2)                      if  filename then                         filetosave = io.open (saveRootPath   filename,  "w+")                          if not fileToSave then                              ngx.say ("failed to open file ",  FileName)                              return                         end                          break                     end                 end            end         end    elseif typ ==  "Body"  then        --  start reading  http body         if fileToSave then             filetosave:wRite (RES)         end    elseif typ ==   "Part_end"  then        --  file write end, close file          if fileToSave then             filetosave:close ()              fileToSave = nil        end                 ret_save = true     elseif typ ==  "EOF"  then        --   End of File read         break    else         ngx.log (ngx.info,  "do other things")      endendif ret_save theN    ngx.say ("Save file ok") end 

By reading the Lualib/resty/upload.lua source code, the module in the process of parsing the file upload request, the main use of a simple similar finite state machine algorithm to achieve, in different states by the corresponding handler processing, supported by the status of the following States include:


 
 

  
  
 
   
state_begin (1), the initial state, is initialized at the time of Upload:new instantiation, the following source code (only retained the backbone):
 
  
 
 

Function _m.new (self, chunk_size, max_line_size)     local boundary  = get_boundary ()     local sock, err = req_socket ()      local read2boundary, err = sock:receiveuntil ("--" &NBSP;  boundary)     local read_line, err = sock:receiveuntil ("\ r \ n")     return setmetatable ({        sock =  sock,        size = chunk_size or chunk_size ,         line_size = max_line_size or max_line_ size,        read2boundary = read2boundary,         read_line = read_line,         boundary = boundary, &nBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;STATE&NBSP;=&NBSP;STATE_BEGIN&NBSP;&NBSP;&NBSP;&NBSP;},&NBSP;MT) End 


 
 

  
  
 
   
State_reading_header (2), start parsing HTTP header message, generally at this stage is mainly used to parse out the file name, boundary and other information; the corresponding handler is Read_header ；
 
  
 
 


 
 

  
  
 
   
state_reading_body (3), start parsing HTTP packet, this phase is to read the contents of the file;
 
  
 
 


 
 

  
  
 
   
state_eof (4), if all the files are parsed and read, then enter the state, generally this stage indicates that the file has been read;
 
  
 
 

The handler of these 4 states are:

State_handlers = {read_preamble, Read_header, Read_body_part, EOF}

-It is important to note that the structure of the read return in different stages/states is different, as the structure returned under state_reading_header is "HEADER", {key, value, line}
-The uploaded file will be saved in the local path /home/steven/openresty/nginx/upload/

3, configure nginx.conf, add location/upfile to receive File upload action, and through Myupload.lua to parse the file upload content after saving to the local file system, as follows:

http {    include       mime.types;     default_type  application/octet-stream;    sendfile         on;    keepalive_timeout  65;     server {        listen        19080;        server_name  localhost;                 location /  {            root   html;             index  index.html  index.htm;        }         Location /upfile {            content_by_lua_file lua/myupload.lua;         }        # redirect  server error pages to the static page /50x.html         error_page   500 502 503 504  /50x.html;         location = /50x.html {             root   html;         }    }}

This article is from the "Quiet lunatic" blog, please make sure to keep this source http://quietmadman.blog.51cto.com/3269500/1766034
Simple file uploading service based on Lua-resty-upload