NAME¶
Pinto::Manual::Tutorial - A narrative introduction to Pinto
VERSION¶
version 0.097
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 -r ~/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 "-r" (or "--root") 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 -r ~/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 -r ~/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 -r ~/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 -r ~/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 -r ~/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 URL 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 look in other repositories for missing prerequisites. Usually, you
only want to install things 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 URL 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 -r ~/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 -r ~/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 -r ~/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 -r ~/repo pull --stack uri_upgrade URI~1.62
Now lets compare the "master" and "uri_upgrade" stacks using
the diff command:
$> pinto -r ~/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 -r ~/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 URL. 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 -r ~/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 -r ~/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 -r ~/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 upgraded until you are sure that the new release includes your patch
or the author has fixed the bug by other means.
$> pinto -r ~/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 -r ~/repo copy master trial
But before you can upgrade URI on the "trial" stack, you'll have to
unpin it there:
$> pinto -r ~/repo unpin --stack trial URI
Now you can proceed to upgrade URI on the stack and try building
"My::App" like this:
$> pinto -r ~/repo pull --stack trial URI~1.62
$> pinto -r ~/repo install --stack trial My::App
If all goes well, remove the pin from the "master" stack and pull your
latest version of URI back to it.
$> pinto -r ~/repo unpin URI
$> pinto -r ~/repo pull URI~1.62
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 -r ~/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 command)
AUTHOR¶
Jeffrey Ryan Thalhammer <jeff@stratopan.com>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2013 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.