When I install an express scaffold app
express
Then run the npm install
npm install
and then run supervisor
supervisor app
I get
Starting child process with 'node app'
Program node app exited with code 0
The app.js file is a basic default express instance.
var express = require('express');
var path = require('path');
var favicon = require('static-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(favicon());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
app.use('/users', users);
/// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
/// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
The app that the generator creates calls ./bin/www
that includes app.js
and then starts listening for traffic.
app.js
does not do this itself.
I think this is important to understand.
app.listen
is not being called in app.js
but is called in ./bin/www
...and this is why you get the exit 0
result. When you call app.js
and not ./bin/www
it runs through the file but because is no command to listen for traffic, the program ends normally...i.e. without having done anything.
That said, you have two options..
Option 1
If you have a ./bin/www
file, you could run supervisor ./bin/www
to get things started.
Option 2
If you don't have the ./bin/www
file for whatever reason, you can edit your app file to look like this.
In your app listing, replace
module.exports = app;
with this
app.set('port', process.env.PORT || 3000);
var server = app.listen(app.get('port'), function() {
debug('Express server listening on port ' + server.address().port);
});
Important Note
While that edit will start the app listening and you won't get an exit 0
any more, I cannot guarantee that the app won't crash with some other error if other files and directories are missing. For example, if the routes
directory isn't present, then the declarations requiring routes/index
and routes/users
will fail and other bad things will happen.