plucky (3) Pinto::Manual::Tutorial.3pm.gz

Provided by: pinto_0.14000-2_all bug

NAME

       Pinto::Manual::Tutorial - A narrative introduction to Pinto

VERSION

       version 0.14

INTRODUCTION

       This tutorial walks you through some of the typical use cases for a Pinto repository.  Along the way, it
       demonstrates most of the pinto commands.  You are encouraged to try the commands as you read along.  If
       you would prefer to get a more condensed summary of features and commands, please read the
       Pinto::Manual::QuickStart. For detailed instructions on installing the software read
       Pinto::Manual::Installing.

BASIC OPERATIONS

   Creating a repository
       The first step in using Pinto is to create a repository, using the init command like this:

         pinto --root ~/repo init

       This will create a new repository in the ~/repo directory.  If that directory does not exist, it will be
       created for you.  If it already does exist, then it must be empty.

       The "--root" (or "-r") option specifies where the repository is. This argument is required for every
       pinto command.  But if you get tired of typing it, you can set the "PINTO_REPOSITORY_ROOT" environment
       variable to point to your repository instead.

       The repository is created with a stack called "master" which is also marked as the default stack.  We'll
       talk more about stacks and default stack later.

   Inspecting the repository
       Now that you have a repository, let's look inside it.  To see the contents of a repository, use the list
       command:

         pinto --root ~/repo list

       You will use the list command quite often.  But at this point, the listing will be empty because there is
       nothing in the repository.  So let's go ahead and add something...

   Adding dependencies
       Suppose we are working on an application called My-App that contains a package called "My::App".  The
       application also depends on the URI package.  Using the pull command, you can bring the URI package into
       your repository:

         pinto --root ~/repo pull URI

       You will be prompted to enter a log message that describes why this change is happening.  The message
       template will include a semi-informative generated message.  Feel free to edit this message as you see
       fit. Save the file and close your editor when you are done.

       Now, you should have URI in your local repository.  So lets look and see what we really got.  Once again,
       you use the list command to see inside the repository:

         pinto --root ~/repo list

       This time, the listing will look something like this:

         rf  URI                            1.60  GAAS/URI-1.60.tar.gz
         rf  URI::Escape                    3.31  GAAS/URI-1.60.tar.gz
         rf  URI::Heuristic                 4.20  GAAS/URI-1.60.tar.gz
         ...

       You can see that the URI package has been added to the repository, as well as all the prerequisites for
       URI, and all of their prerequisites, and so on.

   Adding your own distributions
       Now suppose that you've finished work on My-App and your ready to release the first version.  Using your
       preferred build tool (ExtUtils::MakeMaker, Module::Build, Module::Install etc.) you package a release as
       My- App-1.0.tar.gz.  Now put the distribution into the repository with the add command:

         pinto --root ~/repo add path/to/My-App-1.0.tar.gz

       When you list the repository contents now, it will include the "My::App" package and show you as the
       author of the distribution:

         rl  My::App                         1.0  JEFF/My-App-1.0.tar.gz
         rf  URI                            1.60  GAAS/URI-1.60.tar.gz
         rf  URI::Escape                    3.31  GAAS/URI-1.60.tar.gz
         rf  URI::Heuristic                 4.20  GAAS/URI-1.60.tar.gz
         ...

   Installing packages
       Now the repository contains both your application and all of its prerequisites, so you can install it
       into your environment using the install command:

         pinto --root ~/repo install My::App

       When "My::App" is installed, it will only use the prerequisites that are in your repository.  Even if a
       newer version of URI is released to the CPAN in the future, "My::App" will always be built with the same
       versions of the same prerequisites that you developed and tested against.  This ensures your application
       builds will be stable and predictable.

       On the surface, a Pinto repository looks like an ordinary CPAN, so you can also install packages from it
       using cpanm directly.  All you have to do is point them at the URI of your repository (under the hood,
       this is all the install command is really doing anyway).  For example:

         cpanm --mirror file:///home/jeff/repo --mirror-only My::App

       The "--mirror-only" flag is important because it tells cpanm to not use the "cpanmetadb" to resolve
       packages.  Instead you only want to use the index from your repository.

       You can do the same thing with cpan and cpanp as well.  See their documentation for information on how to
       set the URI of the repository.

   Upgrading a dependency
       Suppose that several weeks have passed since you first released My-App and now URI version 1.62 is
       available on the CPAN.  It has some bug critical fixes that you'd like to get.  Again, we can bring that
       into the repository using the pull command. But since your repository already contains a version of URI,
       you must indicate that you want a *newer* one by specifying the minimum version that you want:

         pinto --root ~/repo pull URI~1.62

       If you look at the listing again, this time you'll see the newer version of URI (and possibly other
       packages as well):

         rl  My::App                         1.0  JEFF/My-App-1.0.tar.gz
         rf  URI                            1.62  GAAS/URI-1.62.tar.gz
         rf  URI::Escape                    3.38  GAAS/URI-1.62.tar.gz
         rf  URI::Heuristic                 4.20  GAAS/URI-1.62.tar.gz
         ...

       If the new version of URI requires any new prerequisites, those will be in the repository too.  Now when
       you install "My::App", you'll get version 1.62 of URI.

WORKING WITH STACKS

       So far in this tutorial, we've treated the repository as a singular resource.  For example, when we
       upgraded URI in the last section, it impacted every person and every application that might have been
       using the repository.  But this kind of broad impact is undesirable. You would prefer to make those kinds
       of changes in isolation and test them before forcing everyone else to upgrade.  This is what stacks are
       designed for.

   What is a stack
       All CPAN-like repositories have an index which maps the latest version of each package to the archive
       that contains it.  Usually, there is only one such index per repository.  But with Pinto, there can be
       many indexes.  Each of these indexes is called a "stack".  This allows you to create different stacks of
       dependencies within a single repository. So you could have a "development" stack and a "production"
       stack. Whenever you add a distribution or upgrade a prerequisite, it only affects one stack.

   The default stack
       Before getting into the gory details, you first need to know about the default stack.  For most
       operations, the name of the stack is an optional parameter.  So if you do not specify a stack explicitly,
       then the operation is applied to whichever stack is marked as the default.

       In any repository, there is never more than one default stack.  When we created this repository, the
       "master" stack was marked as the default. You can also change the default stack or change the name of a
       stack, but we won't go into that here.  See the default command to learn more about that.

       Just remember that "master" is the name of the stack that was created when the repository was first
       initialized.

   Creating a stack
       Suppose your repository contains version 1.60 of URI, but version 1.62 has been released to the CPAN,
       just like in the earlier section.  You want to try upgrading, but this time you're going to do it on a
       separate stack.

       Thus far, everything you've added or pulled into the repository has gone onto the "master" stack.  You
       could create an entirely new stack, but the "master" stack already has the prerequisites for My-App, so
       we're just going to make a clone using the copy command:

         pinto --root ~/repo copy master uri_upgrade

       This creates a new stack called "uri_upgrade".  If you want to see the contents of that stack, just use
       the list command with the "--stack" option:

         pinto --root ~/repo list --stack uri_upgrade

       The listing should be identical to the "master" stack:

         rl  My::App                         1.0  JEFF/My-App-1.0.tar.gz
         rf  URI                            1.60  GAAS/URI-1.60.tar.gz
         ...

   Upgrading a stack
       Now that you've got a separate stack, you can try upgrading URI.  Just as before, you'll use the pull
       command. But this time, you'll tell Pinto that you want the packages to be pulled onto the "uri_upgrade"
       stack:

         pinto --root ~/repo pull --stack uri_upgrade URI~1.62

       Now lets compare the "master" and "uri_upgrade" stacks using the diff command:

         pinto --root ~/repo diff master uri_upgrade

         +rf URI                                              1.62 GAAS/URI-1.62.tar.gz
         +rf URI::Escape                                      3.31 GAAS/URI-1.62.tar.gz
         +rf URI::Heuristic                                   4.20 GAAS/URI-1.62.tar.gz
         ...
         -rf URI                                              1.60 GAAS/URI-1.60.tar.gz
         -rf URI::Escape                                      3.31 GAAS/URI-1.60.tar.gz
         -rf URI::Heuristic                                   4.20 GAAS/URI-1.60.tar.gz

       The output is similar to the diff(1) command. Records starting with a "+" were added and those starting
       with a "-" have been removed.

   Installing from a stack
       With URI upgraded on the "uri_upgrade" stack, you can now try building and testing our application.  All
       you have to do is run the install command and point to the right stack:

         pinto --root ~/repo install --stack uri_upgrade My::App

       This will build My::App using only the prerequisites that are on the "uri_upgrade" stack.  If the tests
       pass, then you can confidently upgrade URI on the "dev" stack as well.

       As mentioned earlier, you can also use cpanm to install modules from your repository.  But when
       installing from a stack other than the default, you must append "stacks/stack_name" to the URI.  For
       example:

         cpanm --mirror file:///home/jeff/repo/stacks/uri_upgrade --mirror-only My::App

USING PINS

       In the last section, we used a stack to experiment with upgrading a dependency.  Fortunately, all the
       tests passed.  But what if the tests didn't pass?  If the problem lies within My-App and you can quickly
       correct it, you might just modify your code, release version 2.0 of My-App, and then proceed to upgrade
       URI on the "master" stack.

       But if the issue is a bug in URI or it will take a long time to fix My-App, then you have a real problem.
       You don't want someone else to upgrade URI, nor do you want it to be upgraded inadvertently to satisfy
       some other prerequisite that My-App may have.  Until the bug is fixed (in either URI or My-App) you need
       to prevent URI from being upgraded.  This is what pins are for.

   Pinning a package
       When you pin a package, that version of the package is forced to stay in a stack.  Any attempt to upgrade
       it (either directly or via another prerequisite) will fail.  To pin a package, use the pin command like
       this:

         pinto --root ~/repo pin URI

       If you look at the listing for the "master" stack again, you'll see something like this:

         ...
         rl  My::App                         1.0  JEFF/My-App-1.0.tar.gz
         rf! URI                            1.60  GAAS/URI-1.60.tar.gz
         rf! URI::Escape                    3.31  GAAS/URI-1.60.tar.gz
         ...

       The "!" near the beginning of the line indicates the package has been pinned.  Notice every package in
       the URI-1.60.tar.gz distribution has been pinned, so it is impossible to partially upgrade a distribution
       (this situation could happen when a package moves into a different distribution).

   Unpinning a packages
       After a while, suppose you fix the problem in My-App or a new version of URI is released that fixes the
       bug.  When that happens, you can unpin URI from the stack using the unpin command:

         pinto --root ~/repo unpin URI

       At this point you're free to upgrade URI to the latest version whenever you're ready.  Just as with
       pinning, when you unpin a package, it unpins every other package it that distribution as well.

USING PINS AND STACKS TOGETHER

       Pins and stacks are used together to help manage change during the development cycle.  For example, you
       could create a stack called "prod" that contains your known-good dependencies.  Likewise, you could
       create a stack called "dev" that contains experimental dependencies for your next release.  Initially,
       the "dev" stack is just a copy of the "prod" stack.

       As development proceeds, you may upgrade or add several packages on the "dev" stack.  If an upgraded
       package breaks your application, then you'll place a pin in that package on the "prod" stack to signal
       that it shouldn't be upgraded.

   Pins and Patches
       Sometimes you may find that a new version of a CPAN distribution has a bug but the author is unable or
       unwilling to fix it (at least not before your next release is due).  In that situation, you may elect to
       make a local patch of the CPAN distribution.

       So suppose that you forked the code for URI and made a local version of the distribution called
       URI-1.60_PATCHED.tar.gz.  You can add it to your repository using the add command:

         pinto --root ~/repo add path/to/URI-1.60_PATCHED.tar.gz

       In this situation, it is wise to pin the package as well, since you do not want it to be updated until
       you are sure that the new release includes your patch or the author has fixed the bug by other means.

         pinto --root ~/repo pin URI

       When the author of URI releases version 1.62 with your patch, you'll want to try it before deciding to
       unpin from your locally patched version.  Just as before, this can be done by cloning the stack with the
       copy command.  Let's call it the "trial" stack this time:

        pinto --root ~/repo copy master trial

       But before you can update URI on the "trial" stack, you'll have to unpin it there:

         pinto --root ~/repo unpin --stack trial URI

       Now you can proceed to update URI on the stack and try building "My::App" like this:

         pinto --root ~/repo update --stack trial URI
         pinto --root ~/repo install --stack trial My::App

       If all the tests pass, then you can merge the changes back to the "master" stack:

         pinto --root ~/repo merge trial master

   Reviewing Past Changes
       As you've noticed by now, each command that changes the state of a stack requires a log message to
       describe it.  You can review those messages using the log command:

         pinto --root ~/repo log

       That should display something like this:

         revision 4a62d7ce-245c-45d4-89f8-987080a90112
         Date: Mar 15, 2013 1:58:05 PM
         User: jeff

              Pin GAAS/URI-1.59.tar.gz

              Pinning URI because it is not causes our foo.t script to fail

         revision 4a62d7ce-245c-45d4-89f8-987080a90112
         Date: Mar 15, 2013 1:58:05 PM
         User: jeff

              Pull GAAS/URI-1.59.tar.gz

              URI is required for HTTP support in our application

         ...

       The header for each message shows who made the change and when it happened. It also has a unique
       identifier similar to Git's SHA-1 digests.  You can use these identifiers to see the diffs between
       different revisions or to reset the stack back to a prior revision [NB: this feature is not actually
       implemented yet].

CONCLUSION

       In this tutorial, you've seen the basic pinto commands for pulling dependencies into the repository, and
       adding your own distributions to the repository.  You've also seen how to use stacks and pins to manage
       your dependencies in the face of some common development obstacles.

       Each command has several options that were not discussed in this tutorial, and there are some commands
       that were not mentioned here at all.  So you are encouraged to explore the manual pages for each command
       and learn more.

SEE ALSO

       Pinto::Manual::QuickStart

       Pinto::Manual::Installing

       Pinto (the library)

       pinto (the application)

AUTHOR

       Jeffrey Ryan Thalhammer <jeff@stratopan.com>

       This software is copyright (c) 2015 by Jeffrey Ryan Thalhammer.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.