Motivation

• Plack?
• Webhosting
  • You can’t run a compiler in your hosted solution to install the needed XS module.
  • You can’t upgrade Perl to use the new try feature.
• Running a server at home
  • Your ISP doesn’t guarantee a static IP address.
  • You don’t want to have a server at home running all the time.

Motivation

• Webhosting
  • You can’t run a compiler in your hosted solution to install the needed XS module.
  • You can’t upgrade Perl to use the new try feature.
• Running a server at home
  • Your ISP doesn’t guarantee a static IP address.
  • You don’t want to have a server at home running all the time.

Rent a virtual server

• Full control of the configuration and installed dependencies.
• I pay €53/year (cheapest HW they offered).
  
• You are responsible for keeping the OS up-to-date and the machine secured. 😱

Operating system

What was available to me:

• None
• Linux
  • Alpine Linux
  • CentOS
  • Debian
  • Devuan
  • Fedora Server
  • openSUSE
  • Ubuntu Server
• FreeBSD

Installation of Perl & modules

• Create a new user to run the application, don’t run it as root!
• Compile your own Perl, or use local::lib.
• Use your favourite CPAN client to install any modules.
• Use root to install development packages for C dependencies.

Registering a domain

In most cases, already included in the service.

From the moment my domain was registered, the server began to be bombarded by various requests (HTTP, SSH).

Fortify the server

• Configure the firewall
  • Only open the ports you really need (HTTP, HTTPS, SSH).
  • Configure your firewall to forward the ports 80 and 443 to the actual ports your application runs on (e.g. 5000).
  • You can also run sshd on a non-standard port.
• Disable root login in sshd_config:

  PermitRootLogin no

Fortify the server (2)

• In case you screw up: emergency console.
  

Fortify the server (3)

• Use fail2ban or a similar tool to block traffic from suspicious IPs

The application

I’ll use the application I run on my server as an example. It lists my Perl talks with slides (and can show the graph we saw in the previous slide).

.
├── cpanfile
├── lib
│   ├── BanGraph.pm
│   ├── MyTemplate.pm
│   ├── NoTrailingSlash.pm
│   └── Talks.pm
├── app.pl
└── talks.in

The application (2)

• Plack::Middleware::Static — serve static files with Plack

  # from the Synopsis
  
  use Plack::Builder;
  
  builder {
      enable 'Static',
          path => qr{^/(images|js|css)/},
          root => './htdocs/';
      $app
  };
  

The application (3)

#! /usr/bin/perl
use warnings;
use strict;

use Plack::Builder;
use FindBin;

use lib './lib';
use Talks;
use BanGraph;
use NoTrailingSlash;
use MyTemplate;

my $root = $FindBin::Bin;

my $app = sub {
    my $env = shift;
    my $status = 200;
    my $headers = ['Content-type' => 'text/html'];

    my $body = [ MyTemplate::page(title => 'E. Choroba',
                                  h1    => 'My Talks',
                                  li    => [Talks::talks($root)]) ];
    return [ $status, $headers, $body ]
};

builder {
    my $dirs_re = Talks::dirs_re($root);

    enable sub { NoTrailingSlash::add_index(shift, $dirs_re) };

    enable 'Static',
        path => sub { s{^/($dirs_re)/$}{$1/index.html} },
        root => $root;

    enable 'Static',
        path => qr{^/$dirs_re/.},
        root => $root;

    mount '/ban.png' => sub { BanGraph::png($root) };

    mount '/' => $app;
};

The application (4)

No Trailing Slash

Unfortunately, this doesn’t work:

enable 'Static',
    path => sub { s{^/($dirs_re)/$}{$1/index.html} },
    root => $root;

The application (4)

No Trailing Slash

Unfortunately, this doesn’t work:

enable 'Static',               # ↓ #
    path => sub { s{^/($dirs_re)/?$}{$1/index.html} },
    root => $root;

It breaks relative links.

The application (5)

No Trailing Slash

package NoTrailingSlash;
use Plack::Request;

sub add_index {
    my ($app, $dirs_re) = @_;
    sub {
        my ($env) = @_;

        my $req = 'Plack::Request'->new($env);
        my $path = $req->path;
        return [ 301, [ Location => "$1/index.html" ], [] ]
            if $path =~ m{^/($dirs_re)$};

        my $res = $app->($env);
        $res
    }
}

__PACKAGE__

Enabling HTTPS

• The easiest and cheapest way is to use Let’s Encrypt.
• Crypt::LE

  le.pl --key account.key        \
        --email name@example.com \
        --csr domain.csr         \
        --csr-key domain.key     \
        --crt domain.crt         \
        --generate-missing       \
        --domains 'example.com'

Running under HTTPS

starman --port 5000             \
        --access-log access.log \
        --ssl-key domain.key    \
        --ssl-cert domain.crt   \
        --enable-ssl            \
        app.pl &> https.log

Wrap up

To run an application on a virtual server, you need

• a server,
• basic system administration skills,
• to install Perl and Plack,
• to install Crypt::LE and Starman to enable HTTPS.