How can I get the port that Mojolicious::Lite chooses?

Question

Joel Berger posted this little program to start a web server to serve local files, and it works great:

use Mojolicious::Lite;

@ARGV = qw(daemon);

use Cwd;
app->static->paths->[0] = getcwd;

any '/' => sub {
    shift->render_static('index.html');
    };

app->start;

I prepopulated the command line in @ARGV because I forget to do that. When it starts, it gives a message telling you which port it chose, using 3000 if it can:

$ perl ~/bin/mojo_cwd
[Fri Mar 29 19:14:09 2013] [info] Listening at "http://*:3000".
Server available at http://127.0.0.1:3000.

I'd like to get that port programmatically so a test suite can know where to look for it, and I'd prefer not to do it by scrapping output. None of my experiments for this were useful and I think I was always going in the wrong direction. It appears that it doesn't choose the port until it starts, and once I call start, that's the end of it.

I don't want to specify the port myself, either.

This isn't an urgent matter. I have a current solution to this with another simple HTTP framework, but I've been looking at replacing most of that stuff with Mojo if I can. Since the old stuff still works, this is really just something nice to have rather than something in my way.

Answer 1

You can't, but the daemon command only binds to port 3000 and will not try anything else unless you tell it to. If you're using Test::Mojo you don't need to know the port in advance anyway, for anything else you can always wrap your application in a little Mojo::Server::Daemon script.

use Mojolicious::Lite;
use Mojo::IOLoop;
use Mojo::Server::Daemon;

get '/' => {text => 'Hello World!'};

my $port   = Mojo::IOLoop->generate_port;
my $daemon = Mojo::Server::Daemon->new(
  app    => app,
  listen => ["http://*:$port"]
);
$daemon->run;

Answer 2

With the --listen param you specify to your app where to listen:

use Mojolicious::Lite;

@ARGV = qw(daemon --listen http://*:5000);

use Cwd;
app->static->paths->[0] = getcwd;

any '/' => sub {
    shift->render_static('index.html');
    };

app->start;

You can access the port number within the app with $self->tx->local_port:

#!/usr/bin/env perl
use Mojolicious::Lite;

@ARGV = qw(daemon --listen http://*:5000);

use Cwd;
app->static->paths->[0] = getcwd;

any '/' => sub {
    my $self = shift;

    $self->render_text('port: '. $self->tx->local_port);
    };

app->start if $ENV{MOJO_MODE} ne 'test';

1;

I like to test Mojolicious apps with Test::Mojo because you get access to the running app, for example, in a file t/test_mojo.t:

use strict;
use warnings;

use feature 'say';

use Test::More;
use Test::Mojo;

$ENV{MOJO_MODE} = 'test';

require "$FindBin::Bin/../test_mojo.pl";

my $t = Test::Mojo->new;
$t->get_ok('/')->status_is(200)->content_is('port: '.$t->tx->remote_port);

say 'local port: '. $t->tx->local_port; #as seen from the user-agent's perspective
say 'remote port:'. $t->tx->remote_port;
done_testing();

I'm not sure I correctly understood what you are trying to accomplish, but I hope this helps you.