1Carton::Doc::FAQ(3) User Contributed Perl Documentation Carton::Doc::FAQ(3)
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6 Carton::Doc::FAQ - Frequently Asked Questions
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9 It looks useful, but what is the use case of this tool?
10 The particular problem that carton is trying to address is this:
11 You develop a Perl-based application, possibly but not limited to
13 webapps, with dozens of CPAN module dependencies. You install these
14 modules on your development machine, and describe these dependencies in
15 your cpanfile.
16 Now you get a production environment, either on PaaS provider or some
18 VPS, you install the dependencies using "cpanm --installdeps ." and it
19 will pull all the latest releases from CPAN as of today and everything
20 just works.
21 A few weeks later, your application becomes more popular, and you think
23 you need another machine to serve more requests. You set up another
24 machine with vanilla perl installation and install the dependencies the
25 same way. That will pull the latest releases from CPAN on that date,
26 rather than the same as what you have today.
27 And that is the problem. It's not likely that everything just breaks
29 one day, but there's always a chance that one of the dependencies
30 breaks an API compatibility, or just uploaded a buggy version to CPAN
31 on that particular day.
32 Carton allows you to lock these dependencies into a version controlled
34 system, so that every time you deploy from a checkout, it is guaranteed
35 that all the same versions are installed into the local environment.
36 How is this different from Pinto or CPAN::Mini::Inject?
38 carton definitely shares the goal with these private CPAN repository
39 management tool. But the main difference is that rather than creating
40 an actual CPAN-like repository that works with any CPAN clients, Carton
41 provides a way to install specific versions of distributions from CPAN,
42 or any CPAN-like mirrors (as well as git repositories in the future
43 version of Carton).
44 Existing tools are designed to work with CPAN clients such as CPAN or
46 CPANPLUS, and have accomplished that by working around the CPAN mirror
47 structure.
48 carton internally does the same thing, but its user interface is
50 centered around the installer, by implementing a wrapper for cpanm, so
51 you can use the same commands in the development mode and deployment
52 mode.
53 Carton automatically maintains the cpanfile.snapshot file, which is
55 meant to be version controlled, inside your application directory. You
56 don't need a separate database, a directory or a web server to maintain
57 tarballs outside your application. The cpanfile.snapshot file can
58 always be generated with "carton install" command, and "carton install"
59 on another machine can use the version in the snapshot.
60 I already use Pinto to create DarkPAN mirror. Can I use Carton with this?
62 Yes, by specifying Pinto mirror as your Carton mirror, you can take a
63 snapshot of your dependencies including your private modules on Pinto,
64 or whatever DarkPAN mirror.
65 I'm already using perlbrew and local::lib. Can I use carton with this?
67 If you're using local::lib already with perlbrew perl, possibly with
68 the new "perlbrew lib" command, that's great! There are multiple
69 benefits over using perlbrew and local::lib for development and use
70 Carton for deployment.
71 The best practice and workflow to get your perl environment as clean as
73 possible with lots of modules installed for quick development would be
74 this:
75 • Install fresh perl using perlbrew. The version must be the same
77 against the version you'll run on the production environment.
78 • Once the installation is done, use "perlbrew lib" command to create
80 a new local lib environment (let's call it devel) and always use
81 the library as a default environment. Install as many modules as
82 you would like into the devel library path.
83 This ensures to have a vanilla "perl" library path as clean as
85 possible.
86 • When you build a new project that you want to manage dependencies
88 via Carton, turn off the devel local::lib and create a new one,
89 like myapp. Install Carton and all of its dependencies to the myapp
90 local::lib path. Then run "carton install" like you normally do.
91 Because devel and myapp are isolated, the modules you installed
93 into devel doesn't affect the process when carton builds the
94 dependency tree for your new project at all. This could often be
95 critical when you have a conditional dependency in your tree, like
96 Any::Moose.
97 I'm using perlbrew, but "carton install" uses system perl, how to fix?
99 The issue is most likelly caused by a inital bad install of "cpanm" or
100 "carton" or both, that ended up with a shebang line pointed to the
101 (wrong) system perl.
102 Re-install Carton on you perlbrew environment
104 Run "cpanm -f Carton". This will force-install Carton, and because
105 your "cpanm" is now using the correct "perl", the same will happen
106 with "carton".
107 Make sure the shebang (the first line) of your "carton" script points
109 to the right perl path, rather than "/usr/bin/perl".
110perl v5.36.0 2022-07-22 Carton::Doc::FAQ(3)