App::MechaCPAN - Mechanize the installation of CPAN things.


  # Install 5.24 into local/perl/
  user@host:~$ mechacpan perl 5.24
  # Install Catalyst into local/
  user@host:~$ mechacpan install Catalyst
  # Install everything from the cpanfile into local/
  # If cpanfile.snapshot exists, it will be consulted first
  user@host:~$ mechacpan install
  # Install perl and everything from the cpanfile into local/
  # If cpanfile.snapshot exists, it will be consulted exclusivly
  user@host:~$ mechacpan deploy
  user@host:~$ zhuli do the thing


App::MechaCPAN Mechanizes the installation of perl and CPAN modules. It is designed to be small and focuses more on installing things in a self-contained manner. That means that everything is installed into a local/ directory.

MechaCPAN was created because installation of a self-contained deployment required at least 4 tools:

plenv/Perl-Build or perlbrew to manage perl installations
cpanm to install packages
local::lib to use locally installed modules
carton to manage and deploy exact package versions

In development these tools are invaluable, but when deploying a package, installing at least 4 packages from github, CPAN and the web just for a small portion of each tool is more than needed. App::MechaCPAN aims to be a single tool that can be used for deploying packages in a automated fashion.

App::MechaCPAN focuses on the aspects of these tools needed for deploying packages to a system. For instance, it will read and use carton's cpanfile.snapshot files, but cannot create them. To create cpanfile.snapshot files, you must use carton.

Should I use App::MechaCPAN instead of <tool>

Probably not, no. It can be used in place of some tools, but its focus is not on the features a developer needs. If your needs are very simple and you don't need many options, you might be able to get away with only using App::MechaCPAN. However be prepared to run into limitations quickly.



  user@host:~/project/$ ls -la
  drwxr-xr-x  6 user users 20480 Jan 18 13:00 .
  drwxr-xr-x 25 user users  4096 Jan 18 13:00 ..
  drwxr-xr-x  8 user users  4096 Jan 18 13:05 .git
  -rw-r--r--  1 user users     7 Jan 18 13:06 .perl-version
  -rw-r--r--  1 user users   109 Jan 18 13:06 cpanfile
  drwxr-xr-x  3 user users  4096 Jan 18 13:10 lib
  user@host:~/project/$ mechacpan deploy

That command will do 2 things:

Install perl

It will install perl into the directory local/perl. It will use the version in .perl-version to decide what version will be installed.

Install modules

Then it will use the installed perl to install all the module dependencies that are listed in the cpanfile.



  user@host:~$ mechacpan perl 5.24

The perl command is used to install perl into local/. This removes the packages dependency on the operating system perl. By default, it tries to be helpful and include lib/ and local/ into @INC automatically, but this feature can be disabled. See App::MechaCPAN::Perl for more details.


  user@host:~$ mechacpan install Catalyst

The install command is used for installing specific modules. All modules are installed into the local/ directory. See See App::MechaCPAN::Install for more details.


  user@host:~$ mechacpan deploy

The deploy command is used for automating a deployment. It will install both perl and all the modules specified from the cpanfile. If there is a cpanfile.snapshot that was created by Carton, deploy will treat the modules lised in the snapshot file as the only modules available to install. See App::MechaCPAN::Deploy for more details.


Besides the options that the individual commands take, App::MechaCPAN takes several that are always available.


By default only informational descriptions of what is happening is shown. Turning verbose on will show every command and all output produced by running each command. Note that this is not the opposite of quiet.


Using quiet means that the normal information descriptions are hidden. Note that this is not the opposite of verbose, turning both options on means no descriptions will be show, but all output from all commands will be.


A log is normally outputted into the local/logs directory. This option will prevent a log from being created.


Changes to a specified directory before any processing is done. This allows you to specify what directory you want local/ to be in. If this isn't provided, the current working directory is used instead.


Every command that App::MechaCPAN runs is given an idle timeout before it is killed and a failure is returned. This timeout is reset every time the command outputs to STDOUT or STDERR. Using the environment variable MECHACPAN_TIMEOUT, you can override or disable this timeout. It is always in seconds and setting it to 0 will disable it. The default is 60 seconds.


This module WILL restart the running script IF it's used as a module (e.g. with use) and the perl that is running is not the version installed in local/. It does this at two points: First right before run-time and Second right after a perl is installed into local/. During restart, App::MechaCPAN will attempt to install itself into local/ unless it was invoked as a fully-contained version of mechacpan.

The scripts and modules that come with App::MechaCPAN are prepared to handle this. If you use App::MechaCPAN as a module, you should to be prepared to handle it as well.

This means that any END and DESTROY blocks WILL NOT RUN. Anything created with File::Temp will be cleaned up, however.


Jon Gentle <>


Copyright 2017- Jon Gentle


This is free software. You may redistribute copies of it under the terms of the Artistic License 2 as published by The Perl Foundation.