NodeMCU ESP8266 simple httpd (web server) example

I want to add a simple webserver to my NodeMCU bot, and...

<begin old man grump>
In looking, I did not find anything really clean-cut, most of the examples I find for anything these days are so cluttered and look like they where written by a robot monkey (a poorly coded one). It's seems if there is no ide to keep things neat and clean, kids these days don't. 

</begin old man grump>

With NodeMCU, you get kind of what they say it is, a Node.js type environment (kind of... :-) Most real Nodish programs are acting like a web server on a larger machine, like a Linux, Mac or even windows. When you look at the Node code, it always looks like they are really writing for the web client side and not the web server.  It's a mess.

For what I want from it that does not really matter. I just want a simple easy to use scripting language to bang out code for the ESP with and Lua fits the bill for the most part (until the MicroPython port is completed :) I can keep my old man code all neat and beautiful!

Now back to the show...

My plans for the server is two-fold, control and status. I want to be able to see whats going on the bot and send commands to drive it or turn things on and off.

I figured I would share this for anyone wanting a clean NodeMCU httpd example.

Update 04/03/2015 - Added function to parse and build a lua table with the request data.

-- Simple NodeMCU web server (done is a not so nodeie fashion :-)
--
-- Written by Scott Beasley 2015
-- Open and free to change and use. Enjoy.
--

-- Your Wifi connection data
local SSID = "xxxxxxxx"
local SSID_PASSWORD = "xxxxxxxx"

local function connect (conn, data)
   local query_data

   conn:on ("receive",
      function (cn, req_data)
         query_data = get_http_req (req_data)
         print (query_data["METHOD"] .. " " .. " " .. query_data["User-Agent"])
         cn:send ("Hello World from ESP8266 and NodeMCU!!")
         -- Close the connection for the request
         cn:close ( )
      end)
end

function wait_for_wifi_conn ( )
   tmr.alarm (1, 1000, 1, function ( )
      if wifi.sta.getip ( ) == nil then
         print ("Waiting for Wifi connection")
      else
         tmr.stop (1)
         print ("ESP8266 mode is: " .. wifi.getmode ( ))
         print ("The module MAC address is: " .. wifi.ap.getmac ( ))
         print ("Config done, IP is " .. wifi.sta.getip ( ))
      end
   end)
end

-- Build and return a table of the http request data
function get_http_req (instr)
   local t = {}
   local first = nil
   local key, v, strt_ndx, end_ndx

   for str in string.gmatch (instr, "([^\n]+)") do
      -- First line in the method and path
      if (first == nil) then
         first = 1
         strt_ndx, end_ndx = string.find (str, "([^ ]+)")
         v = trim (string.sub (str, end_ndx + 2))
         key = trim (string.sub (str, strt_ndx, end_ndx))
         t["METHOD"] = key
         t["REQUEST"] = v
      else -- Process and reamaining ":" fields
         strt_ndx, end_ndx = string.find (str, "([^:]+)")
         if (end_ndx ~= nil) then
            v = trim (string.sub (str, end_ndx + 2))
            key = trim (string.sub (str, strt_ndx, end_ndx))
            t[key] = v
         end
      end
   end

   return t
end

-- String trim left and right
function trim (s)
  return (s:gsub ("^%s*(.-)%s*$", "%1"))
end

-- Configure the ESP as a station (client)
wifi.setmode (wifi.STATION)
wifi.sta.config (SSID, SSID_PASSWORD)
wifi.sta.autoconnect (1)

-- Hang out until we get a wifi connection before the httpd server is started.
wait_for_wifi_conn ( )

-- Create the httpd server
svr = net.createServer (net.TCP, 30)

-- Server listening on port 80, call connect function if a request is received
svr:listen (80, connect)