Raspy Http Server running on startup

Challenge

So we want to run a simple http server that will start running when the Raspberry Pi starts up?

Install node.js on Pi

Follow these simple instructions to install node.js on pi

wget http://node-arm.herokuapp.com/node_latest_armhf.deb 
sudo dpkg -i node_latest_armhf.deb

Test:

node --version

On your Pi create a folder called ~/nodejs.

Create a file called https.js on Mac with the following:

var http = require('http');
var number = 0;

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  var num = number.toString();
  res.end('Hello World ' + num + '\n' );
}).listen(1337, 'xxx.x.x.x');

var interval = setInterval(function(){
  number++; 
},2000);

console.log('Server running at http://xxx.x.x.x:1337/');

where xxx.x.x.x is the IP address of your Raspberry Pi. This server will increment a number every 2 seconds indefinitely and publish it.

Copy the file https.js to Pi's ~/nodejs folder as follows:

scp ./https.js pi@raspberrypi:~/nodejs
            ..or..
scp ./https.js pi@xxx.x.x.x:~/nodejs

On your pi edit the file /etc/rc.local. Add the following line:

su pi -c 'node /home/pi/nodejs/https.js'

This will run the node command at startup as the user pi (who installed node.js).

This way your http server will start running as soon as your Pi restarts.

To test on a browser

http://xxx.x.x.x:1337/

This will show a page as follows. The number will increment by one at each refresh at 2 second interval.

Hello World 905

Thanks to Pieter Beulque's tips here.

Quick and dirty Http client/server code with node.js

Http Server (sampler)

This node.js Http server samples a metric and serves it at regular intervals.

var http = require('http');
var number = 0;

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  var num = number.toString();
  res.end('Hello World ' + num + '\n' );
}).listen(1337, '127.0.0.1');

var interval = setInterval(function(){
  number++; 
},2000);

console.log('Server running at http://127.0.0.1:1337/');

Http Client (poller)

This node.js Http client polls (requests) data at regular intervals.

To test start server on a terminal, then client on a different terminal.

var http = require('http');

var interval = setInterval(function(){

  http.get("http://127.0.0.1:1337", function(res) {
    console.log("Got response: " + res.statusCode);
    res.on('data', function (chunk) {
      console.log('BODY: ' + chunk);
    });
  }).on('error', function(e) {
    console.log("Got error: " + e.message);
  });
},2000);

Http Client (agent)

This node.js Http client, when requested redirects GET request to the server on port 1337 and returns the response on port 1338.

To test start server on a terminal, then agent on a different terminal. On a browser request/refresh "http://127.0.0.1/1338".

var http = require('http');

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});

  http.get("http://127.0.0.1:1337", function(_res) {
    console.log("Got response: " + _res.statusCode);
    _res.on('data', function (chunk) {
      res.end('BODY: ' + chunk);
      console.log('BODY: ' + chunk);
    });
   }).on('error', function(e) {
      console.log("Got error: " + e.message);
  });

}).listen(1338, '127.0.0.1');