perl development environment tooling

Perl Development Environment Tooling

Jason Crome Technical Lead, All Around the World

August 25, 2016 Copyright 2016, Jason A. Crome

Who’s this for?• Devs who need to work with multiple versions of Perl

(module authors, large enterprises, masochists, etc.)

• Devs who have been through dependency hell

• Devs who need a specific Perl setup but system restrictions interfere

• Devs looking to make deployment easier

• People frustrated with bugs in system Perl

• People who want to use/test the latest Perl featuresCopyright 2016, Jason A. CromeAugust 25, 2016

What We’ll Cover• local::lib

• perlbrew

• plenv

• Carton

• Carmel and Pinto (very minimally)

Copyright 2016, Jason A. CromeAugust 25, 2016

local::lib

• Helps work with system Perl

• Helps avoid sysadmins

• Makes deployments easier

• Installs Perl modules to home (or another) directory, rather than updating the system lib/ directory.


local::lib… But why?

• Sometimes you can’t install the Perl you need

• Sometimes you install from packages (Debian, FreeBSD, etc.) that don’t update often.

• Sometimes your sysadmin is cautious and prevents you from installing what you need


About local::lib

• Your local modules take precedence

• Your local modules have no effect on other users

• System Perl doesn’t even need local::lib installed for you to use it! (to do this, look at the bootstrapping technique)


Using local::lib# Initialize local::lib (.bashrc, etc.) eval $( perl -Mlocal::lib );

# Install a module cpanm Dancer2

# In your code: # Nothing, you already set this up in your shell :)


perlbrew and plenv• Helps avoid system Perl

• Helps avoid system admins

• Makes deployments easier

• Useful for testing an app against other Perl versions

• Install one or more Perl versions to your home directory

• More flexible than local::libCopyright 2016, Jason A. CromeAugust 25, 2016

perlbrew and plenvjason@darwin PerlDancer/Dancer2-official (master) 7:22:47 git » plenv versions system aaw-5.22.0 bump-5.24.0 crome-plated dancer-5.10.1 * dancer-5.22.0 (set by ~/Projects/PerlDancer/.perl-version) fifo-5.22.0 pearlbee-5.18.4 vetminder-5.22.0 vetminder-5.24.0 veure-5.18.4 veure-5.22.1 veure-5.24.0 waste-classic waste-tng


perlbrew and plenv

• Not compatible with each other

• If you want to switch after you have installed one of these, you must completely uninstall the other


perlbrew - Pros and Cons

• It’s easy

• Don’t need sudo to install Perl modules

• Onus is placed on dev to change Perl versions when it is appropriate to do so

• When you switch Perl versions, you stay on that version until you switch to another


How perlbrew Works• By abusing your $PATH, that’s how.

• When you switch versions of Perl, perlbrew changes your path to point to the desired version of Perl

• Does this by exporting some shell functions that switches $PATH when needed

• Easy to understand

• Written in PerlCopyright 2016, Jason A. CromeAugust 25, 2016

Installing perlbrew# From the shell (all you should really need) \curl -L https://install.perlbrew.pl | bash perlbrew init

# Or, from CPAN sudo cpan App::perlbrew


Using perlbrew# What versions can be installed? perlbrew available

# Install a version perlbrew install perl-5.24.0

# List installed versions perlbrew list

# Change versions perlbrew switch perl-5.18.4 # Test against all installed versions perlbrew exec dzil test


plenv - Pros and Cons

• Lets you set local and global Perl configs

• This leaves .perl-version files in its wake. Add to .gitignore

• No $PATH munging to work

• Less functionality than perlbrew out of the box


How plenv works• Installs to one location and adds it to your path

• Creates a shim for each executable (base Perl plus those added through CPAN)

• Implemented in bash (no global shell functions)

• Shim looks at the appropriate .perl-version file to determine which Perl version to use


What’s in .perl-version?jason@darwin Projects/veure (master*) 10:57:21 git » cat .perl-version veure-5.24.0


Installing plenv# On mac? brew install plenv brew install perlbuild


Installing plenv# Otherwise git clone https://github.com/tokuhirom/plenv.git ~/.plenv

echo 'export PATH="$HOME/.plenv/bin:$PATH"' >> ~/.bash_profile

echo 'eval "$(plenv init -)"' >> ~/.bash_profile

exec $SHELL -l

git clone https://github.com/tokuhirom/Perl-Build.git ~/.plenv/plugins/perl-build/


Using plenv# What versions can be installed? plenv install --list

# Install a version plenv install 5.24.0 plenv install 5.24.0 --as dancer2-5.24.0

# List installed versions plenv versions

# Change versions plenv local dancer2-5.24.0 plenv global system # Test against all installed versions (need plenv-contrib) plenv exec-all dzil test


Carton• Top-notch dependency management

• Can specify a specific range of allowed versions, or a specific one. This is huge!

• Runs your app with only the modules you specify

• Super-easy to deploy and distribute your app with no module/dependency hell


Why’s this useful?• Consider Veure (Tau Station, our game)

• Developer stymied by test failures

• Only one on team using Test::Class::Moose 0.77

• Spend inordinate amount of time tracking down to find it was a version issue

• Better dependency/module management would have made this a non-issue


How Carton works

• Uses cpanfile to specify versions

• Can create a cpanfile.snapshot to pin specific versions that are currently installed

• Distribute these to other machines with your application to deploy/run your app


What’s in .cpanfile?# This version and any after requires “Dancer2", ">= 0.163000”;

# No specific version needed requires "Dancer2::Plugin::Database" => 0;

on "test" => sub { requires “Test::More" => "0"; requires “Test::Class::Moose”, ”>= 0.73, < 0.77”; };


Installing Carton# From CPAN cpanm Carton


Using Carton# Install module version listed in cpanfile from CPAN carton install

# Modules are installed to local/ # Version info captured to cpanfile.snapshot

# Commit to github git add cpanfile.snapshot git commit -m”Capture module version snapshot.” git push

# Clone to other machine, then carton install --deployment

# Now, run your app carton exec plackup sbin/app.psgi


Bundling with Carton

• carton bundle bundles the tarballs for your modules and their dependencies into a directory

• Easy to distribute across a local network

• Deploy via carton install --cached

• Can install without CPAN or an internet connection


A final note

• Carton creates two things in your project directory: local/ and .carton

• These should not be distributed with your app

• Make it easy: add to .gitignore


Carmel and Pinto

Honestly, I have little experience here

Both are marked experimental.

USE AT YOUR OWN RISKCopyright 2016, Jason A. CromeAugust 25, 2016

Carmel• Set up your own CPAN-like repositories of modules

• Carmel keeps a repo of all modules you build with it

• When you need a module, uses cpanfile to determine what it needs from that repo and builds @INC appropriately.

• Carmel and Carton are made to work togetherCopyright 2016, Jason A. CromeAugust 25, 2016

Pinto• Pinto works like a self-curated PAUSE/CPAN

• Unlike CPAN, lets you keep different module versions for dev, prod, test, etc.

• Has version control. Easy to rollback if you add a broken module release

• Allows you to use only modules and versions you want

• Works when you are offline/CPAN is downCopyright 2016, Jason A. CromeAugust 25, 2016

Thank you!


Resources• local::lib - https://metacpan.org/pod/local::lib

• perlbrew - https://perlbrew.pl/

• plenv - https://github.com/tokuhirom/plenv

• Carton - https://metacpan.org/pod/Carton

• Carmel - https://metacpan.org/pod/Carmel

• Pinto - https://metacpan.org/pod/PintoCopyright 2016, Jason A. CromeAugust 25, 2016

perl development environment tooling

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