NAME

    Carmel - CPAN Artifact Repository Manager

SYNOPSIS

      # Run with a directory with cpanfile
      carmel install
    
      # Manually pull a module if you don't have it
      carmel inject DBI@1.633 Plack@1.0000
    
      # list all the modules to be loaded
      carmel list
    
      # list all the modules in a tree
      carmel tree
    
      # show a location where a module is installed
      carmel show Plack
    
      # update Plack to the latest
      carmel update Plack
    
      # update all the modules in the snapshot
      carmel update
    
      # Runs your perl script with modules from artifacts
      carmel exec perl ...
    
      # Requires all your modules in cpanfile in one shot
      carmel exec perl -e 'use Carmel::Preload;'
    
      # Roll out the currently selected modules into ./local
      carmel rollout
    
      # package modules tarballs and index into ./vendor/cache
      carmel package
    
      # use Carmel packages inside a script (without carmel exec)
      perl -e 'use Carmel::Setup; ...'
    
      # prints export PATH=... etc for shell scripting
      carmel export
    
      # find a module in a repository
      carmel find DBI
    
      # find a module matching the version query
      carmel find Plack ">= 1.0000, < 1.1000"

DESCRIPTION

    Carmel is yet another CPAN module manager.

    Unlike traditional CPAN module installer, Carmel keeps the build of
    your dependencies in a central repository, then select the library
    paths to include upon runtime in development.

    Carmel also allows you to rollout all the files in a traditional perl
    INC directory structure, which is useful to use in a production
    environment, such as containers.

WORKFLOW

    Here's a typical workflow of using Carmel.

      # On your development environment
      > cat cpanfile
      requires 'Plack', '0.9980';
      requires 'Starman', '0.2000';
    
      > carmel install
      > echo /.carmel >> .gitignore
      > git add cpanfile cpanfile.snapshot .gitignore
      > git commit -m "add Plack and Starman"
    
      # On a new setup, or another developer's machine
      > git pull
      > carmel install
      > carmel exec starman -p 8080 myapp.psgi
    
      # Add a new dependency
      > echo "requires 'Try::Tiny';" >> cpanfile
      > carmel install
      > git commit -am 'Add Try::Tiny'
    
      # Update Plack to the latest
      > carmel update Plack
    
      # Production environment: Roll out to ./local
      > carmel rollout
      > perl -Ilocal/lib/perl5 local/bin/starman -p 8080 myapp.psgi

HOW IT WORKS

    Carmel will keep the build directory (artifacts) after a cpanm
    installation in a repository, which defaults to
    $HOME/.carmel/{version}-{archname}/builds, and your directory structure
    would look like:

      $HOME/.carmel/5.20.1-darwin-2level/builds
        Plack-1.0033/
          blib/
            arch/
            lib/
        URI-1.64/
          blib/
            arch/
            lib/
        URI-1.63/
          blib/
            arch/
            lib/

    Carmel scans this directory and creates the mapping of which version of
    any package belongs to which build directory.

    Given the list of modules and requirements from cpanfile, carmel
    install computes which versions satisfy the requirements best, and if
    there isn't, installs the modules from CPAN to put it to the artifact
    repository. The computed mappings are preserved as a snapshot in
    cpanfile.snapshot.

    Once the snapshot is created, each following carmel command runs uses
    both cpanfile and cpanfile.snapshot to determine the best versions to
    satisfy the requirements. When you update cpanfile to bump a version or
    add a new module, carmel will install the new dependencies and update
    the snapshot accordingly.

    carmel exec command, like install command, lists the build directories
    and .pm files you need from the repository, and then prepend the
    mappings of these files in the @INC hook. This is a handy way to run a
    perl program using the dependencies pinned by Carmel, without changing
    any include path.

    carmel update command allows you to selectively update a dependency
    while preserving other dependencies in the snapshot. carmel update
    Plack for example pulls the latest version of Plack from CPAN (and its
    dependencies, if it needs a newer version than pinned in the snapshot),
    and updates the snapshot properly. Running carmel update without any
    arguments would update all the modules in cpanfile, including its
    dependencies.

    On a production environment, you might want to use the carmel rollout
    command, which saves all the files included in the cpanfile, pinned
    with cpanfile.snapshot, to the local directory. This directory can be
    included like a regular perl's library path, with
    PERL5LIB=/path/to/local/lib/perl5, or with use lib, and you don't need
    to use carmel command in production this way.

 SNAPSHOT SUPPORT

    As of v0.1.29, Carmel supports saving and loading snapshot file in
    cpanfile.snapshot, in a compatible format with Carton. Versions saved
    in the snapshot file will be preserved across multiple runs of Carmel
    across machines, so that versions frozen in one environment can be
    committed to a source code repository, and can be reproduced in another
    box, so long as the perl version and architecture is the same.

DIFFERENCES WITH CARTON

    Carmel shares the same goal with Carton, where you can manage your
    dependencies by declaring them in cpanfile, and pinning them in
    cpanfile.snapshot. Most of the commands work the same way, so Carmel
    can most effectively be a drop-in replacement for Carton, if you're
    currently using it.

    Here's a few key differences between Carmel and Carton:

      * Carton does not manage what's currently being installed in local
      directory. It just runs cpanm command with -L local, with a hope that
      nothing has changed the directory except Carton, and whatever is in
      the directory won't conflict with the snapshot file. This can easily
      conflict when cpanfile.snapshot is updated by multiple developers or
      when you continuously update the dependencies across multiple
      machines.

      Carmel manages all the dependencies for your project in the Carmel
      repository under $HOME/.carmel, and nothing is installed under your
      project directory on development. The local directory is only created
      when you request it via carmel rollout command, and it's safe to run
      multiple times. Running carmel install after pulling the changes to
      the snapshot file will always install the correct dependencies from
      the snapshot file, as compared to Carton, which doesn't honor the
      snapshot on a regular install command, if whatever version in local
      already satisfies the version in cpanfile.

      * Carton has no easy way to undo a change once you update a version
      of a module in local, because which version is actually selected is
      only preserved as a file inside the directory, that's not managed by
      Carton. To undo a change you have to remove the entire local
      directory to start over.

      Carmel preserves this information to the cpanfile.snapshot file, and
      every invocation of Carmel resolves the dependencies declared in
      cpanfile and pinned in cpanfile.snapshot dynamically, to create a
      stable dependency tree, without relying on anything in a directory
      under your project other than the snapshot file. Undoing the change
      in cpanfile.snapshot file immediately reverts the change.

COMMUNITY

    https://github.com/miyagawa/Carmel

      Code repository, Wiki and Issue Tracker

AUTHOR

    Tatsuhiko Miyagawa <miyagawa@bulknews.net>

COPYRIGHT

    Copyright 2015- Tatsuhiko Miyagawa

LICENSE

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

SEE ALSO

    App::cpanminus Carton

