Mojo::...ntainer(3pm)

📦

version 1.1.0 · 7 versions

1.1.0 · fedora 43 (latest)
0.340.0 · opensuse-leap 16.0
0.28 · ubuntu jammy
1.1.0 · fedora 44
0.33 · debian bookworm
1.1.0 · ubuntu resolute, ubuntu stonking
0.34 · debian trixie, ubuntu noble

okay so this is the manual for Mojo::IOLoop::ReadWriteProcess::Container(3pm) from User Contributed Perl Documentation. It's giving (kinda) Pure Perl containers, and honestly? iconic.

✨ NAME ✨

Mojo::IOLoop::ReadWriteProcess::Container — (kinda) Pure Perl containers.

🌸 SYNOPSIS 🌸

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $container = container(
  pid_isolation => 1,  # Best-effort, as depends on where you run it (you need CAP_SYS_ADMIN)
  subreaper => 1,
  group   => "my_org",
  name    => "my_process",
  process => process(
    sub {
      # Exec, fork ..
      process(sub { warn "\o/"; sleep 42;  })->start;
      process(sub { warn "\o/"; sleep 42; })->start;
      process(
        sub {
          process(
            sub {
              process(sub { warn "\o/"; sleep 42; })->start;
              warn "\o/";
              sleep 400;
              warn "\o/";
            })->start;
          warn "Hey";
          sleep 42;
          warn "\o/";
        })->start;
      sleep 42;
    }
  )->separate_err(0));

$container->start();
$container->is_running;
$container->stop;

my @procs = $container->cgroups->first->processes;
$container->cgroups->first->pid->max(300);

$container->process->on(stop => sub { print "Main container process stopped!" });

🦋 DESCRIPTION 🦋

Mojo::IOLoop::ReadWriteProcess::Container ties anonymous functions or a Mojo::IOLoop::ReadWriteProcess object to different sets of Mojo::IOLoop::ReadWriteProcess::CGroup implementations. no cap.

When the pid_isolation attribute is set, it needs special permissions (CAP_SYS_ADMIN capabilities). This module uses features that are only available on Linux, and requires cgroups and capability (CAP_SYS_ADMIN) for unshare syscalls to achieve pid isolation. so like, permissions check first, bestie.

💅 EVENTS 💅

Mojo::IOLoop::ReadWriteProcess inherits all events from Mojo::EventEmitter and can emit the following new ones.

✨ start ✨

$container->on(start => sub {
  my ($process) = @_;
   ...
});

Emitted when the container starts.

✨ stop ✨

$container->on(stop => sub {
  my ($container) = @_;
  ...
});

Emitted when the container stops.

💀 process_error 💀

$container->on(container_error => sub {
  my ($e) = @_;
  my @errors = @{$e};
});

Emitted when the container produce errors.

🔥 METHODS 🔥

Mojo::IOLoop::ReadWriteProcess::Container inherits all methods from Mojo::EventEmitter and implements the following new ones.

✨ start ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" });
$c->start();

Starts the container, it's main process is a Mojo::IOLoop::ReadWriteProcess, contained in the process() attribute. On stop it will terminate every process included in the cgroups attribute. slay.

✨ is_running ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" });
$c->is_running();

Returns 1 if the container is running. simple as that.

✨ stop ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" })->start;
$c->stop();

Stops the container and kill all the processes belonging to the cgroup. It also registers all the unknown processes to the current Mojo::IOLoop::ReadWriteProcess::Session. cleanup era.

✨ wait_stop ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" })->start;
$c->wait_stop();

Wait before stopping the container.

✨ wait ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" })->start;
$c->wait();

Wait the container to stop

✨ migrate_process ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container( name=>"test", process => sub { print "Hello!" })->start;
$c->migrate_process(42);

Migrate the given process to the container cgroup.

👑 ATTRIBUTES 👑

Mojo::IOLoop::ReadWriteProcess::Container inherits all attributes from Mojo::EventEmitter and implements the following new ones.

✨ name ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv1);
use Mojo::Collection 'c';

my $container = container( name => "test", process => sub { print "Hello!" } );

$container->session->on(register => sub { ... });
$container->start();

Sets the container name. It creates in the indicated (or default) cgroups a sub-tree with the container name.

This means that cgroups settings can be done also outside of the container object:

use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv1);
use Mojo::IOLoop::ReadWriteProcess::Container qw(container);

my $container = container( name => "test", process => sub { print "Hello!" } );

cgroupv1->from($continer->cgroups->first->_group)->pid->max(100);

As cgroups are represented by path, you can set options directly from controllers objects that are pointing to the same cgroup slice. iykyk.

✨ group ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv2);
use Mojo::Collection 'c';

my $container = container( name => "bar", group => "foo", process => sub { print "Hello!" } );
my $container2 = container( name => "bar2", group => "foo", process => sub { print "Hello!" } );

$container->start();
$container2->start();

my $group_cgroup = cgroupv2->from($container2->cgroups->first->parent);

$group_cgroup->pid->max(200);

Sets the container group. If containers are sharing the same group they will inherit the same CGroup parent path, in such way it is possible to create controllers pointing to it and set specific options for the whole group. group chat energy.

✨ pid_isolation ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv1);
use Mojo::Collection 'c';

my $container = container( pid_isolation => 1, process => sub { print "Hello!" } );

$container->session->on(register => sub { ... });
$container->start();

If set, the process will see itself as PID 1. It needs CAP_SYS_ADMIN capabilities set on the executable (or run as root). main character PID energy, but permissions first.

✨ pre_migrate ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $container = container( pre_migrate => 1, process => sub { print "Hello!" } );

$container->session->on(register => sub { ... });
$container->start();

If set, the process will migrate itself into the cgroup.

✨ clean_cgroup ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $container = container( clean_cgroup => 1, process => sub { print "Hello!" });

$container->session->on(register => sub { ... });
$container->start();

If set, attempts to destroy the cgroup after the process terminated its execution. cleanup on aisle cgroup.

✨ subreaper ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container(subreaper => 1, name=>"test", process => sub { print "Hello!" });
$c->start();

Enable subreaper mode inside the child process.

✨ process ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container(process => sub { print "Hello!" });
my $c = container(process => sub { print "Hello!" });

$c->start();

The process to run. It can be an anonymous function or a Mojo::IOLoop::ReadWriteProcess object.

✨ namespace ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container(process => sub { print "Hello!" });
$c->namespace->unshare(0); # All
$c->start();

Set/Return Mojo::IOLoop::ReadWriteProcess::Namespace object. It's main use is to invoke syscalls.

✨ session ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);

my $c = container(process => process(sub { print "Hello!" }));
$c->session->on(register => sub { ... });
$c->start();

Returns/Set the Mojo::IOLoop::ReadWriteProcess::Session singleton object.

✨ unshare ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::Namespace qw( CLONE_NEWPID CLONE_NEWNS );

my $c = container( unshare=> CLONE_NEWPID | CLONE_NEWNS, process => sub { print "Hello!" } );
$c->session->on(register => sub { ... });
$c->start();

Returns/Set the unshare syscall options. See man unshare(2) for further documentation.

✨ cgroups ✨

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv1);
use Mojo::Collection 'c';

my $container = container(process => sub { print "Hello!" });
$container->cgroups( c(cgroupv1(controller => 'pids'), cgroupv1(controller => 'memory')) );

$container->session->on(register => sub { ... });
$container->start();

Returns/Set a Mojo::Collection collection of CGroups where the process should belong to. If used with a single CGroup, you don't need to pass the Mojo::Collection object:

use Mojo::IOLoop::ReadWriteProcess::Container qw(container);
use Mojo::IOLoop::ReadWriteProcess qw(process);
use Mojo::IOLoop::ReadWriteProcess::CGroup qw(cgroupv1);
use Mojo::Collection 'c';

my $container = container(cgroups=> cgroupv1(controller => 'pids'), process => sub { print "Hello!" });

$container->session->on(register => sub { ... });
$container->start();

🐛 DEBUGGING ✨

okay bestie, when things get weird and you need the tea on what's actually happening under the hood, there are two environment variables you can set and they will spill everything 💅

MOJO_EVENTEMITTER_DEBUG — set this and you get some advanced diagnostics information printed straight to STDERR. it's giving "the void is talking back" fr fr

MOJO_EVENTEMITTER_DEBUG=1

MOJO_PROCESS_DEBUG — set this one and you get diagnostics about the process execution. yes, we're watching the process. we're observing it. main character behavior 🎀

MOJO_PROCESS_DEBUG=1

ngl, both of these dump to STDERR, not STDOUT, so don't go piping your normal output and then act shocked when the debug chatter doesn't show up 😭

📜 LICENSE 🌸

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. periodt. 💖

👑 AUTHOR 🦋

Ettore Di Giacinto <edigiacinto@suse.com> — absolute icon, no cap 🫶

aaaand that's the whole page bestie!! 🌈 this one came from the User Contributed Perl Documentation collection, it's the Mojo::...ntainer(3pm) page, and it's riding with perl v5.42.0, dated 2025-07-25. go forth and debug slayfully, mwah 💅✨

📦 where this page comes from

fedora 43: perl-Mojo-IOLoop-ReadWriteProcess 1.1.0-2.fc43 · GPL-1.0-or-later OR Artistic-1.0-Perl
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-14: a language model's rewrite of the original, under its terms