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Carton::Doc::FAQ(3)   User Contributed Perl Documentation  Carton::Doc::FAQ(3)

NAME
       Carton::Doc::FAQ	- Frequently Asked Questions

QUESTIONS
   It looks useful, but	what is	the use	case of	this tool?
       The particular problem that carton is trying to address is this:

       You develop a Perl-based	application, possibly but not limited to
       webapps,	with dozens of CPAN module dependencies. You install these
       modules on your development machine, and	describe these dependencies in
       your cpanfile.

       Now you get a production	environment, either on PaaS provider or	some
       VPS, you	install	the dependencies using "cpanm --installdeps ." and it
       will pull all the latest	releases from CPAN as of today and everything
       just works.

       A few weeks later, your application becomes more	popular, and you think
       you need	another	machine	to serve more requests.	You set	up another
       machine with vanilla perl installation and install the dependencies the
       same way. That will pull	the latest releases from CPAN on that date,
       rather than the same as what you	have today.

       And that	is the problem.	It's not likely	that everything	just breaks
       one day,	but there's always a chance that one of	the dependencies
       breaks an API compatibility, or just uploaded a buggy version to	CPAN
       on that particular day.

       Carton allows you to lock these dependencies into a version controlled
       system, so that every time you deploy from a checkout, it is guaranteed
       that all	the same versions are installed	into the local environment.

   How is this different from Pinto or CPAN::Mini::Inject?
       carton definitely shares	the goal with these private CPAN repository
       management tool.	But the	main difference	is that	rather than creating
       an actual CPAN-like repository that works with any CPAN clients,	Carton
       provides	a way to install specific versions of distributions from CPAN,
       or any CPAN-like	mirrors	(as well as git	repositories in	the future
       version of Carton).

       Existing	tools are designed to work with	CPAN clients such as CPAN or
       CPANPLUS, and have accomplished that by working around the CPAN mirror
       structure.

       carton internally does the same thing, but its user interface is
       centered	around the installer, by implementing a	wrapper	for cpanm, so
       you can use the same commands in	the development	mode and deployment
       mode.

       Carton automatically maintains the cpanfile.snapshot file, which	is
       meant to	be version controlled, inside your application directory. You
       don't need a separate database, a directory or a	web server to maintain
       tarballs	outside	your application. The cpanfile.snapshot	file can
       always be generated with	"carton	install" command, and "carton install"
       on another machine can use the version in the snapshot.

   I already use Pinto to create DarkPAN mirror. Can I use Carton with this?
       Yes, by specifying Pinto	mirror as your Carton mirror, you can take a
       snapshot	of your	dependencies including your private modules on Pinto,
       or whatever DarkPAN mirror.

   I'm already using perlbrew and local::lib. Can I use	carton with this?
       If you're using local::lib already with perlbrew	perl, possibly with
       the new "perlbrew lib" command, that's great! There are multiple
       benefits	over using perlbrew and	local::lib for development and use
       Carton for deployment.

       The best	practice and workflow to get your perl environment as clean as
       possible	with lots of modules installed for quick development would be
       this:

       o   Install fresh perl using perlbrew. The version must be the same
	   against the version you'll run on the production environment.

       o   Once	the installation is done, use "perlbrew	lib" command to	create
	   a new local lib environment (let's call it devel) and always	use
	   the library as a default environment. Install as many modules as
	   you would like into the devel library path.

	   This	ensures	to have	a vanilla "perl" library path as clean as
	   possible.

       o   When	you build a new	project	that you want to manage	dependencies
	   via Carton, turn off	the devel local::lib and create	a new one,
	   like	myapp. Install Carton and all of its dependencies to the myapp
	   local::lib path. Then run "carton install" like you normally	do.

	   Because devel and myapp are isolated, the modules you installed
	   into	devel doesn't affect the process when carton builds the
	   dependency tree for your new	project	at all.	This could often be
	   critical when you have a conditional	dependency in your tree, like
	   Any::Moose.

   I'm using perlbrew, but "carton install" uses system	perl, how to fix?
       The issue is most likelly caused	by a inital bad	install	of "cpanm" or
       "carton"	or both, that ended up with a shebang line pointed to the
       (wrong) system perl.

       Re-install Carton on you	perlbrew environment
	   Run "cpanm -f Carton". This will force-install Carton, and because
	   your	"cpanm"	is now using the correct "perl", the same will happen
	   with	"carton".

       Make sure the shebang (the first	line) of your "carton" script points
       to the right perl path, rather than "/usr/bin/perl".

perl v5.32.1			  2016-05-24		   Carton::Doc::FAQ(3)

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