/README.md

# What is node.js auto restart

It is a set of examples and a module with common problems solved.

It allows easy development and stable production.



 - Run on boot:

   To make your program run automaticaly on boot with Upsrart(you need to configure a .sh file and a .conf file)

 - Auto restart:

   autoexit module to watch all .js files if they have been changed and to restart nodejs. 

 - A description of how to make your program crash proof from javascript errors. (segfaults still crash)

 - Auto reload a module:

   makes sense for fast development of slow loading app,



"http://github.com/shimondoodkin/node-hot-reload":http://github.com/shimondoodkin/node-hot-reload.



## How to use nodejs auto restart:

Copy `nodejs.sh` and `autoexit.js` to root folder of your application 

for example to `/var/www`. Copying of `autoexit.js` is optional and it can be included from deps folder



### Add to your script at top: 

    require.paths.unshift(__dirname); //make local paths accessible



### And to your script at end:



    // exit if any js file or template file is changed.

    // it is ok because this script encapsualated in a batch while(true);

    // so it runs again after it exits.

    var autoexit_watch=require('autoexit').watch;

    //

    var on_autoexit=function (filename) { } // if it returns false it means to ignore exit this time;  

    autoexit_watch(__dirname,".js", on_autoexit);

    //autoexit_watch(__dirname+"/templates",".html", on_autoexit);







### You might want to use: `try-catch` that will make your applicaiton not crash on errors

    try

    {

     //your code

    }

    catch(e)

    {

     console.log(e.stack)

    }



Also after serving one sucsessful request (application is fully loaded) I add an on error error handler:



    if(!app_loaded)

    {

     process.on('uncaughtException', function (err) {

       console.log('Caught exception: ' + err.stack);

     });

     app_loaded=true;

    }



As i like it, I want it to crash on load errors and exit the application but not on application errors.



### Example:

    require.paths.unshift(__dirname); //make local paths accessible

    

    var http = require('http');

    var app_loaded=false;



    http.createServer(function (req, res) {



      if(!app_loaded)

      {

       process.on('uncaughtException', function (err) {

       console.log('Caught exception: ' + err.stack);

       });

       app_loaded=true;

      }



      try

      {    



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

      res.end('Hello World\n');

      

      }

      catch(e)

      {

       console.log(e.stack);

      }

      

    }).listen(8124);

    console.log('Server running at http://127.0.0.1:8124/');

    

    // exit if any js file or template file is changed.

    // it is ok because this script encapsualated in a batch while(true);

    // so it runs again after it exits.

    var autoexit_watch=require('autoexit').watch;

    //

    var on_autoexit=function () { console.log('bye bye'); } 

    autoexit_watch(__dirname,".js", on_autoexit);

    //autoexit_watch(__dirname+"/templates",".html", on_autoexit);









### Edit nodejs.sh

Edit `nodejs.sh` to match to your server.js filename.





### To launch nodejs you type

    cd /var/www

    ./nodejs.sh



### To make it work with upstart  - make it run on boot

Copy `nodejs.conf` to `/etc/init/`

and modify it to point to nodejs.sh



Upstart is originated in Ubuntu linux. if your linux does not have upstart. An option for you migh be to install upstart.



### To use upstart you type :



    [command] + [init filename without conf extention]



    start nodejs 

    stop nodejs

    restrt nodejs



### When i start to develop I connect to the server with ssh and run:



    stop nodejs

    cd /var/www

    ./nodejs.sh





Then I will start to see application output and errors on the screen

If I want to stop the server I press `Control + C`

and the script stops.

note: the output will not bet visible if logging is configured in node.sh. the output will go to log.



### Nginx?

Yes I also use Nginx as front. (but it is not required). I use it

to let me in the future to change and integrate different servers seemlessly.

It is  basicly:  nginx<->nodejs as an upstream.

also i have added php-cgi to nginx to use +Rock mongo+ - a mongodb db editor.

also i've added a log.php , log file viewer so don't even need ssh.





### Multi Process

you can put nginx or haproxy as a front and create several .conf files for the upstart.



in each you modify the execution line to contain port number ex.:



in the nodejs1.conf

    exec sudo -u www-data /bin/bash /var/www/nodejs-mongodb-app/nodejs.sh 8001

in the nodejs2.conf

    exec sudo -u www-data /bin/bash /var/www/nodejs-mongodb-app/nodejs.sh 8002



and make port as an argument to your server.js.

    //http.createServer(server_handler_function).listen(process.argv[2]||8001);

    //see http://nodejs.org/api.html#process-argv-58

    //process.argv.forEach(function (val, index, array) {

    //  console.log(index + ': ' + val);

    //});



To achive best performance. it was found by testing (during development of twisted and nginx) that the number of processors should much the number of cores not more not lest. 

   

### the idea behind the architecture 

the idea is to add an extra level of fail-safety by using a stable system shell script to restart node instead of node itself.