So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Viewable online at: http://www.python.org/dev/peps/pep-0453/
Abstract
This PEP proposes the inclusion of a method for explicitly bootstrapping
pip_ as the default package manager for Python. It also proposes that the
distributions of Python available via Python.org will automatically run this
explicit bootstrapping method and a recommendation to third party
redistributors of Python to also provide pip by default (in a way reasonable
for their distributions).
Proposal
This PEP proposes the inclusion of a getpip bootstrapping module in
Python 3.4, as well as in the next maintenance releases of Python 3.3 and
2.7.
This PEP does not propose making pip (or any dependencies) part of the standard library. Instead, pip will be a bundled application provided along with CPython for the convenience of Python users, but subject to its own development life cycle and able to be upgraded independently of the core interpreter and standard library.
Rationale
Installing a third party package into a freshly installed Python requires first installing the package manager. This requires users ahead of time to know what the package manager is, where to get them from, and how to install them. The effect of this is that these external projects are required to either blindly assume the user already has the package manager installed, needs to duplicate the instructions and tell their users how to install the package manager, or completely forgo the use of dependencies to ease installation concerns for their users.
All of the available options have their own drawbacks.
If a project simply assumes a user already has the tooling then they get a confusing error message when the installation command doesn't work. Some operating may ease this pain by providing a global hook that looks for commands that don't exist and suggest an OS package they can install to make the command work.
If a project chooses to duplicate the installation instructions and tell their users how to install the package manager before telling them how to install their own project then whenever these instructions need updates they need updating by every project that has duplicated them. This will inevitably not happen in every case leaving many different instructions on how to install it many of them broken or less than optimal. These additional instructions might also confuse users who try to install the package manager a second time thinking that it's part of the instructions of installing the project.
The problem of stale instructions can be alleviated by referencing pip's
own bootstrapping instructions
<http://www.pip-installer.org/en/latest/installing.html>__, but the user
experience involved still isn't good (especially on Windows, where
downloading and running a Python script with the default OS configuration is
significantly more painful than downloading and running a binary executable
or installer). The situation becomes even more complicated when multiple
Python versions are involved (for example, parallel installations of Python
2 and Python 3).
The projects that have decided to forgo dependencies altogether are forced to either duplicate the efforts of other projects by inventing their own solutions to problems or are required to simply include the other projects in their own source trees. Both of these options present their own problems either in duplicating maintenance work across the ecosystem or potentially leaving users vulnerable to security issues because the included code or duplicated efforts are not automatically updated when upstream releases a new version.
By providing the package manager by default it will be easier for users trying
to install these third party packages as well as easier for the people
distributing them as they no longer need to pick the lesser evil. This will
become more important in the future as the Wheel_ package format does not have
a built in "installer" in the form of setup.py so users wishing to install
a Wheel package will need an installer even in the simple case.
Reducing the burden of actually installing a third party package should also decrease the pressure to add every useful module to the standard library. This will allow additions to the standard library to focus more on why Python should have a particular tool out of the box instead of needing to use the difficulty in installing a package as justification for inclusion.
Providing a standard installation system also helps with bootstrapping
alternate build and installer systems, such as setuptools,
zc.buildout and the hashdist/conda combination that
is aimed
specifically at the scientific community. So long as
pip install <tool> works, then a standard Python-specific installer
provides a reasonably secure, cross platform mechanism to get access to
these utilities.
Explicit Bootstrapping
An additional module called getpip will be added to the standard library
whose purpose is to install pip and any of its dependencies into the
appropriate location (most commonly site-packages). It will expose a single
callable named bootstrap() as well as offer direct execution via
python -m getpip. Options for installing it such as index server,
installation location (--user, --root, etc) will also be
available
to enable different installation schemes.
It is believed that users will want the most recent versions available to be installed so that they can take advantage of the new advances in packaging. Since any particular version of Python has a much longer staying power than a version of pip in order to satisfy a user's desire to have the most recent version the bootstrap will contact PyPI, find the latest version, download it, and then install it. This process is security sensitive, difficult to get right, and evolves along with the rest of packaging.
Instead of attempting to maintain a "mini pip" for the sole purpose of
installing pip the getpip module will, as an implementation detail,
include a private copy of pip and its dependencies which will be used to
discover and install pip from PyPI. It is important to stress that this
private copy of pip is only an implementation detail and it should not
be relied on or assumed to exist.
Not all users will have network access to PyPI whenever they run the
bootstrap. In order to ensure that these users will still be able to
bootstrap pip the bootstrap will fallback to simply installing the included
copy of pip. The pip --no-download command line option will be supported
to force installation of the bundled version, without even attempting to
contact PyPI.
This presents a balance between giving users the latest version of pip, saving them from needing to immediately upgrade pip after bootstrapping it, and allowing the bootstrap to work offline in situations where users might already have packages downloaded that they wish to install.
Proposed CLI
The proposed CLI is based on a subset of the existing pip install
options::
Usage:
python -m getpip [options]
Download Options:
--no-download Install the bundled version, don't attempt to download
-i, --index-url <url> Base URL of Python Package Index (default
https://pypi.python.org/simple/).
--proxy <proxy> Specify a proxy in the form
[user:passwd@]proxy.server:port.
--timeout <sec> Set the socket timeout (default 15 seconds).
--cert <path> Path to alternate CA bundle.
Installation Options:
-U, --upgrade Upgrade pip and dependencies, even if already installed
--user Install using the user scheme.
--root <dir> Install everything relative to this alternate root
directory.
Additional options (such as verbosity and logging options) may also be supported.
Automatic installation of setuptools
pip currently depends on setuptools to handle metadata
generation
during the build process, along with some other features. While work is
ongoing to reduce or eliminate this dependency, it is not clear if that
work will be complete for pip 1.5 (which is the version likely to be
bundled with Python 3.4.0).
This PEP proposes that, if pip still requires it, setuptools will be
bundled along with pip itself, and thus installed when running
python -m getpip.
However, this behaviour will be officially declared an implementation
detail. Other projects which explicitly require setuptools should still
provide an appropriate dependency declaration, rather than assuming
setuptools will always be installed alongside pip.
Updating the bundled pip
In order to keep up with evolutions in packaging as well as providing users
who are using the offline installation method with as recent version as
possible the getpip module should be updated to the latest versions of
everything it bootstraps. After each new pip release, and again during the
preparation for any release of Python, a script, provided as part of this
PEP, should be run to ensure the bundled packages have been updated to the
latest versions.
This means that maintenance releases of the CPython installers will include
an updated version of the getpip bootstrap module.
Feature Addition in Maintenance Releases
Adding a new module to the standard library in Python 2.7 and 3.3 maintenance releases breaks the usual policy of "no new features in maintenance releases".
It is being proposed in this case as the bootstrapping problem greatly affects the experience of new users, especially on Python 2 where many Python 3 standard library improvements are available as backports on PyPI, but are not included in the Python 2 standard library.
By updating Python 2.7, 3.3 and 3.4 to easily bootstrap the PyPI ecosystem, this should aid the vast majority of Python users, rather than only those with the freedom to adopt Python 3.4 as soon as it is released.
This is also a matter of starting as we mean to continue: similar to IDLE
(see PEP 434), getpip will be permanently exempted from the "no new
features in maintenance releases" restriction, as it will include (and
rely on) upgraded versions of pip even in maintenance releases.
Pre-installation
During the installation of Python from Python.org python -m getpip should
be executed, leaving people using the Windows or OSX installers with a working
copy of pip once the installation has completed. The exact method of this is
left up to the maintainers of the installers, however if the bootstrapping is
optional it should be opt-out rather than opt-in.
The Windows and OSX installers distributed by Python.org will automatically
attempt to run python -m getpip by default however the make
install
and make altinstall commands of the source distribution will not. Note
that getpip itself will still be installed normally (as it is a regular
part of the standard library), only the installation of pip and its
dependencies will be skipped.
Keeping the pip bootstrapping as a separate step for make based
installations should minimize the changes CPython redistributors need to
make to their build processes. Avoiding the layer of indirection through
make for the getpip invocation also ensures those installing from a custom
source build can easily force an offline installation of pip, install it
from a private index server, or skip installing pip entirely.
Open Question: Uninstallation
No changes are currently proposed to the uninstallation process. The bootstrapped pip will be installed the same way as any other pip installed packages, and will be handled in the same way as any other post-install additions to the Python environment.
At least on Windows, that means the bootstrapped files will be left behind after uninstallation, since those files won't be associated with the Python MSI installer.
.. note::
Perhaps the installer needs to be updated to clobber everything in site-packages and the Scripts directory, but I would prefer not to make this PEP conditional on that change.
Open Question: Script Execution on Windows
While the Windows installer was updated in Python 3.3 to make python
available on the PATH, no such change was made to include the scripts
directory. This PEP proposes that this be changed to also add the scripts
directory.
Without this change, the most reliable way to invoke pip on Windows (without
tinkering with paths) is actually be py -m pip (or py -3 -m pip
if both Python 2 and 3 are installed) rather than simply calling pip.
Adding the scripts directory to the system PATH would mean that pip
works reliably in the "only one Python installation" case, with
py -m pip needed only for the parallel installation case.
Python Virtual Environments
Python 3.3 included a standard library approach to virtual Python environments
through the venv module. Since it's release it has become clear that very
few users have been willing to use this feature in part due to the lack of
an installer present by default inside of the virtual environment. They have
instead opted to continue using the virtualenv package which does
include
pip installed by default.
To make the venv more useful to users it will be modified to issue the
pip bootstrap by default inside of the new environment while creating it. This
will allow people the same convenience inside of the virtual environment as
this PEP provides outside of it as well as bringing the venv module closer
to feature parity with the external virtualenv package making it a more
suitable replacement. To handles cases where a user does not wish to have pip
bootstrapped into their virtual environment a --without-pip option will be
added. The --no-download option will also be supported, to force the
use of the bundled pip rather than retrieving the latest version from
PyPI.
Bundling CA Certificates with CPython
The reference getpip implementation includes the pip CA
bundle along with the rest of pip. This means CPython effectively includes
a CA bundle that is used solely for getpip.
This is considered desirable, as it ensures that pip will behave the
same across all supported versions of Python, even those prior to Python
3.4 that cannot access the system certificate store on Windows.
Recommendations for Downstream Distributors
A common source of Python installations are through downstream distributors such as the various Linux Distributions [#ubuntu]_ [#debian]_ [#fedora]_, OSX package managers [#homebrew]_, or python specific tools [#conda]_. In order to provide a consistent, user friendly experience to all users of Python regardless of how they attained Python this PEP recommends and asks that downstream distributors:
Ensure that whenever Python is installed pip is also installed.
- This may take the form of separate packages with dependencies on each other so that installing the Python package installs the pip package and installing the pip package installs the Python package.
Do not remove the bundled copy of pip.
- This is required for offline installation of pip into a virtual environment.
- This is similar to the existing
virtualenvpackage for which many downstream distributors have already made exception to the common "debundling" policy. - This does mean that if
pipneeds to be updated due to a security issue, so does the bundled version in thegetpipbootstrap module - However, altering the bundled version of pip to remove the embedded CA certificate bundle and rely the system CA bundle instead is a reasonable change.
Migrate build systems to utilize
pip_ andWheel_ instead of directly usingsetup.py.- This will ensure that downstream packages can more easily utilize the
new metadata formats which may not have a
setup.py.
- This will ensure that downstream packages can more easily utilize the
new metadata formats which may not have a
Ensure that all features of this PEP continue to work with any modifications made.
- Online installation of the latest version of pip into a global or virtual
python environment using
python -m getpip. - Offline installation of the bundled version of pip into a global or virtual
python environment using
python -m getpip. pip install --upgrade pipin a global installation should not affect any already created virtual environments.pip install --upgrade pipin a virtual environment should not affect the global installation.
- Online installation of the latest version of pip into a global or virtual
python environment using
Policies & Governance
The maintainers of the bundled software and the CPython core team will work together in order to address the needs of both. The bundled software will still remain external to CPython and this PEP does not include CPython subsuming the responsibilities or decisions of the bundled software. This PEP aims to decrease the burden on end users wanting to use third party packages and the decisions inside it are pragmatic ones that represent the trust that the Python community has placed in the authors and maintainers of the bundled software.
Backwards Compatibility
The public API of the getpip module itself will fall under the typical
backwards compatibility policy of Python for its standard library. The
externally developed software that this PEP bundles does not.
Most importantly, this means that the bundled version of pip may gain new features in CPython maintenance releases, and pip continues to operate on its own 6 month release cycle rather than CPython's 18-24 month cycle.
Security Releases
Any security update that affects the getpip module will be shared prior
to
release with the PSRT. The PSRT will then decide if the issue inside warrants
a security release of Python.
Appendix: Rejected Proposals
Implicit Bootstrap
PEP439_, the predecessor for this PEP, proposes its own solution. Its
solution involves shipping a fake pip command that when executed would
implicitly bootstrap and install pip if it does not already exist. This has
been rejected because it is too "magical". It hides from the end user when
exactly the pip command will be installed or that it is being installed at all.
It also does not provide any recommendations or considerations towards
downstream packagers who wish to manage the globally installed pip through the
mechanisms typical for their system.
Including pip In the Standard Library
Similar to this PEP is the proposal of just including pip in the standard
library. This would ensure that Python always includes pip and fixes all of the
end user facing problems with not having pip present by default. This has been
rejected because we've learned through the inclusion and history of
distutils in the standard library that losing the ability to update the
packaging tools independently can leave the tooling in a state of constant
limbo. Making it unable to ever reasonably evolve in a timeframe that actually
affects users as any new features will not be available to the general
population for years.
Allowing the packaging tools to progress separately from the Python release and adoption schedules allows the improvements to be used by all members of the Python community and not just those able to live on the bleeding edge of Python releases.
.. _Wheel: http://www.python.org/dev/peps/pep-0427/ .. _pip: http://www.pip-installer.org .. _setuptools: https://pypi.python.org/pypi/setuptools .. _PEP439: http://www.python.org/dev/peps/pep-0439/
References
.. [#ubuntu] Ubuntu <http://www.ubuntu.com/>
.. [#debian] Debian <http://www.debian.org>
.. [#fedora] Fedora <https://fedoraproject.org/>
.. [#homebrew] Homebrew <http://brew.sh/>
.. [#conda] Conda <http://www.continuum.io/blog/conda>
Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
On 15 September 2013 16:33, Donald Stufft donald@stufft.io wrote: [...]
pip currently depends on
setuptools to handle metadata generation
during the build process, along with some other features. While work is
ongoing to reduce or eliminate this dependency, it is not clear if that
work will be complete for pip 1.5 (which is the version likely to be
bundled with Python 3.4.0).
Might be better worded as "(which is the version likely to be current when Python 3.4.0 is released)",
This PEP proposes that, if pip still requires it,
setuptools will be
bundled along with pip itself, and thus installed when running
python -m getpip.
Do you mean "thus installed"? Surely the current version from PyPI will be installed except in --no-download cases?
Actually, I'd be inclined to avoid the use of the word "bundled". getpip has an "internal copy" of pip, which users aren't supposed to care about except for the fact that it's the "static version included for offline installation", and there's also the "current version on PyPI" which is what is normally installed. I don't think that any of the 3 quoted terms really corresponds to "bundled" in the sense that people will expect it to mean.
Updating the bundled pip
[..]
This means that maintenance releases of the CPython installers will include
an updated version of the getpip bootstrap module.
Is this solely the copy of pip that will be updated, or if there are logic changes in getpip itself (I can't immediately think of any that might be added) will they be included as well?
While the Windows installer was updated in Python 3.3
to make python
available on the PATH,
Correction: it was updated to optionally make Python available, and the option is off by default.
no such change was made to include the scripts directory. This PEP proposes that this be changed to also add the scripts directory.
Without this change, the most reliable way to invoke pip on Windows (without
tinkering with paths) is actually be py -m pip (or py -3 -m pip
if both Python 2 and 3 are installed) rather than simply calling pip.
Adding the scripts directory to the system PATH would mean that pip
works reliably in the "only one Python installation" case, with
py -m pip needed only for the parallel installation case.
Technically, for the 'the user only selected the "put Python on PATH" option for one installation" case.... And if the user selected it more than once, they are already in the land of confusing which-comes-first PATH ordering fun, so working out which pip gets run won't be much extra pain :-)
I think it's also still an open question as to whether getpip should be run in --user mode by default (or as an option) as part of the installation process. There are issues around PATH with doing so, as well as possible confusion because pip does not default to --user. I suspect that the probably answer here should be "--user installs are too immature at the moment to have as the default, but we should look at this again later".
But these minor points aside, I'm +1 on this.
Paul
On Sunday, 15 September 2013, Donald Stufft wrote:
So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Viewable online at: http://www.python.org/dev/peps/pep-0453/
<snip PEP text>Hey,
I've been trying hard to follow the discussions but please forgive this question if its has been hashed out already.
I was a little concerned, despite it being an implementation detail, about bundling a pip which ends up being present somewhere whwerever the bootstrap is.
I know the concept of a mini-pip has been abandoned, but I couldn't help thinking about the pip / setuptools as wheels in Nick's roadmap summary. Instead of a copy of pip, could there not be minimal code to simply fetch the wheel and install that or perhaps even use it directly (a la what was possible with eggs)?
Perhaps that is already too much code and there are good reasons not to do this, but hoped asking would make it clear.
Thanks, Alex J Burke.
On Sep 15, 2013, at 3:56 PM, Alex Burke alexjeffburke@gmail.com wrote:
On Sunday, 15 September 2013, Donald Stufft wrote: So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Viewable online at: http://www.python.org/dev/peps/pep-0453/
<snip PEP text>Hey,
I've been trying hard to follow the discussions but please forgive this question if its has been hashed out already.
I was a little concerned, despite it being an implementation detail, about bundling a pip which ends up being present somewhere whwerever the bootstrap is.
I know the concept of a mini-pip has been abandoned, but I couldn't help thinking about the pip / setuptools as wheels in Nick's roadmap summary. Instead of a copy of pip, could there not be minimal code to simply fetch the wheel and install that or perhaps even use it directly (a la what was possible with eggs)?
Perhaps that is already too much code and there are good reasons not to do this, but hoped asking would make it clear.
Thanks, Alex J Burke.
Basically three reasons:
- There's a lot of code to handle a variety of situations in pip, it would
be much harder to extract this code and keep it up to date in a way
that the "mini pip" could use it. It would also not be as battle worn as
the pip code.
- On top of the one time cost there is the ongoing cost. As the packaging
ecosystem progresses the stdlib implementation will need to be kept
up to date as well as the pip code.
- We need to include a copy of pip in order to support offline installs either
way. Since we have the private copy there to support offline we might as
well use it to handle everything.
Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
On Sun, Sep 15, 2013 at 6:33 PM, Donald Stufft donald@stufft.io wrote:
So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Just want to say that It is good to see that over three year pip
has
gained strength to be the tool of choice for Python package
management. My attempt to propose this three years ago had failed,
because there was no package management tool people could agree to,
even though the proposal was for the interactive user script that
could recommend all :
https://mail.python.org/pipermail/distutils-sig/2010-March/015894.html
So, why PIP?
anatoly t.
On 15 September 2013 16:33, Donald Stufft donald@stufft.io wrote:
So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Explicit Bootstrapping
An additional module called getpip will be added to the standard library
whose purpose is to install pip and any of its dependencies into the
appropriate location (most commonly site-packages). It will expose a single
callable named bootstrap() as well as offer direct execution via
python -m getpip. Options for installing it such as index server,
installation location (--user, --root, etc) will also be
available
to enable different installation schemes.
It is believed that users will want the most recent versions available to be installed so that they can take advantage of the new advances in packaging. Since any particular version of Python has a much longer staying power than a version of pip in order to satisfy a user's desire to have the most recent version the bootstrap will contact PyPI, find the latest version, download it, and then install it. This process is security sensitive, difficult to get right, and evolves along with the rest of packaging.
Instead of attempting to maintain a "mini pip" for the sole purpose of
installing pip the getpip module will, as an implementation detail,
include a private copy of pip and its dependencies which will be used to
discover and install pip from PyPI. It is important to stress that this
private copy of pip is only an implementation detail and it should not
be relied on or assumed to exist.
Not all users will have network access to PyPI whenever they run the
bootstrap. In order to ensure that these users will still be able to
bootstrap pip the bootstrap will fallback to simply installing the included
copy of pip. The pip --no-download command line option will be supported
to force installation of the bundled version, without even attempting to
contact PyPI.
This presents a balance between giving users the latest version of pip, saving them from needing to immediately upgrade pip after bootstrapping it, and allowing the bootstrap to work offline in situations where users might already have packages downloaded that they wish to install.
I still don't understand why this is preferable to just shipping a recent stable pip/setuptools and providing instructions to update post-install. That would surely be a lot simpler not just to implement but for others to understand.
If I'm happy to use the bundled version of pip then why do I need to do anything to make it usable after having already run the installer? If I want the new version then why is 'py -m getpip' better than 'py -m pip install -U pip'?
>
Recommendations for Downstream Distributors
A common source of Python installations are through downstream distributors such as the various Linux Distributions [#ubuntu]_ [#debian]_ [#fedora]_, OSX package managers [#homebrew]_, or python specific tools [#conda]_. In order to provide a consistent, user friendly experience to all users of Python regardless of how they attained Python this PEP recommends and asks that downstream distributors:
Ensure that whenever Python is installed pip is also installed.
- This may take the form of separate packages with dependencies on each other so that installing the Python package installs the pip package and installing the pip package installs the Python package.
Do not remove the bundled copy of pip.
Are distros really going to be okay with this idea? Many of them have CPython in their base install so you're basically asking that they always ship a parallel package management system that is outside of their control.
Personally I think that it's unfortunate that distro package managers don't have a --user option like pip does but I've always assumed that they had some good reason for not wanting any old user to be able to easily install things without admin/root privileges. This would break that arrangement since any user would be able to use 'pip install --user' to install anything from PyPI. I imagine that lots of deployment sites would want to disable this even if the distro has it enabled by default.
Oscar
Hi,
Donald Stufft <donald <at> stufft.io> writes:
This is also a matter of starting as we mean to
continue: similar to IDLE
(see PEP 434), getpip will be permanently exempted from the "no new
features in maintenance releases" restriction, as it will include (and
rely on) upgraded versions of pip even in maintenance releases.
This sounds rather weird. If the whole point of getpip is for people
to
get the latest pip version without it being bundled, the why does getpip
itself need to be upgraded in maintenance releases?
(barring bug and compatibility fixes, obviously)
The reference getpip implementation
includes the pip CA
bundle along with the rest of pip. This means CPython effectively includes
a CA bundle that is used solely for getpip.
This is considered desirable, as it ensures that pip will behave the
same across all supported versions of Python, even those prior to Python
3.4 that cannot access the system certificate store on Windows.
You mean... it ensures that getpip will behave the same, right?
Policies & Governance
The maintainers of the bundled software and the CPython core team will work together in order to address the needs of both. The bundled software will still remain external to CPython and this PEP does not include CPython subsuming the responsibilities or decisions of the bundled software.
Ok, to be clear: "bundled software" means the private pip copy, not "getpip" itself, right? Otherwise I'm afraid I don't agree :-) Whichever public API is exposed by the CPython distribution is certainly within the realm and moral responsibility of the CPython core developers.
By the way, the parallel with IDLE here is flawed, because IDLE is a very annex and secondary piece of software that few people care about (which is why IDLE was several times proposed out of the stdlib).
For the rest, +1.
Regards
Antoine.
On 16 Sep 2013 20:06, "Antoine Pitrou" antoine@python.org wrote: > >
Hi,
Donald Stufft <donald <at> stufft.io> writes: >
This is also a matter of starting as we mean to
continue: similar to
IDLE
(see PEP 434), getpip will be permanently exempted from the "no new
features in maintenance releases" restriction, as it will include (and
rely on) upgraded versions of pip even in maintenance releases.
This sounds rather weird. If the whole point of getpip is for
people
to
get the latest pip version without it being bundled, the why does
getpip
itself need to be upgraded in maintenance releases?
(barring bug and compatibility fixes, obviously)
Because getpip contains a complete private copy of pip that it installs in the "--no-download" case and otherwise uses to download the latest version.
Technically you could lock down the getpip shim to prevent feature additions, but I don't see the point in introducing cross-version inconsistencies in maintained versions if we decide the shim should expose more pip features.
>
The reference
getpip implementation includes the pip CA
bundle along with the rest of pip. This means CPython effectively
includes
a CA bundle that is used solely for getpip.
This is considered desirable, as it ensures that pip will behave the
same across all supported versions of Python, even those prior to Python
3.4 that cannot access the system certificate store on Windows.
You mean... it ensures that getpip will behave the same, right?
Both, really. The behaviour of getpip and the behaviour of a "--no-download" pip bootstrap will be the same, since they use the same software.
>
Policies & Governance
The maintainers of the bundled software and the CPython core team will work together in order to address the needs of both. The bundled software will still remain external to CPython and this PEP does not include CPython subsuming the responsibilities or decisions of the bundled software.
Ok, to be clear: "bundled software" means the private pip copy, not "getpip" itself, right? Otherwise I'm afraid I don't agree :-) Whichever public API is exposed by the CPython distribution is certainly within the realm and moral responsibility of the CPython core developers.
getpip delegates to the included private copy of pip for the installation process, so it may gain new features in maintenance releases (e.g. signature validation if we get a TUF based system working).
This means I'm OK with requiring no backwards incompatible changes to getpip in maintenance releases, I'm not OK with disallowing feature additions (hence the comparison to IDLE).
>
By the way, the parallel with IDLE here is flawed, because IDLE is a very annex and secondary piece of software that few people care about (which is why IDLE was several times proposed out of the stdlib).
If this bundling approach works for pip, it wouldn't surprise me if IDLE migrated to this multi-version bundled application model in 3.5.
Cheers, Nick.
>
For the rest, +1.
Regards
Antoine.
Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig
Nick Coghlan <ncoghlan <at> gmail.com> writes:
On 16 Sep 2013 20:06, "Antoine Pitrou" <antoine <at> python.org> wrote: > >
Hi,
Donald Stufft <donald <at> stufft.io> writes: >
This is also a matter of starting as we mean to
continue: similar to IDLE
(see PEP 434), getpip will be permanently exempted from the "no new
features in maintenance releases" restriction, as it will include (and
rely on) upgraded versions of pip even in maintenance releases.
This sounds rather weird. If the whole point of getpip is for people
to
get the latest pip version without it being bundled, the why does getpip
itself need to be upgraded in maintenance releases?
(barring bug and compatibility fixes, obviously)
Because getpip contains a complete private copy of pip that it installs in
the "--no-download" case and otherwise uses to download the latest version.
Technically you could lock down the getpip shim to prevent feature
additions, but I don't see the point in introducing cross-version
inconsistencies in maintained versions if we decide the shim should expose
more pip features.
Well... Cross-version inconsistencies are the reason we have several maintained versions in the first place.
If you upgrade getpip's functionality in maintenance releases, this means someone with Python 2.7.7 won't get the same experience as, e.g., someone with Python 2.7.6 or 2.7.8. It breaks the expectation that maintenance releases are basically substitutable to each other (modulo, of course, bug fixes). It also makes support more complicated for the various Python communities ("wait, which 2.7 version do you have? then your getpip doesn't have that option, you must instead do this and that...").
It will probably also make Python maintenance more difficult for distributors (e.g. Linux distros) which commit to API stability between bugfix versions.
Regards
Antoine.
On 16 Sep 2013 19:55, "Oscar Benjamin" oscar.j.benjamin@gmail.com wrote: >
On 15 September 2013 16:33, Donald Stufft donald@stufft.io wrote:
So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Explicit Bootstrapping
An additional module called getpip will be added to the standard
library
whose purpose is to install pip and any of its dependencies into the
appropriate location (most commonly site-packages). It will expose a
single
callable named bootstrap() as well as offer direct execution via
python -m getpip. Options for installing it such as index server,
installation location (--user, --root, etc) will also be
available
to enable different installation schemes.
It is believed that users will want the most recent versions available to be installed so that they can take advantage of the new advances in packaging. Since any particular version of Python has a much longer staying power than a version of pip in order to satisfy a user's desire to have the most recent version the bootstrap will contact PyPI, find the latest version, download it, and then install it. This process is security sensitive, difficult to get right, and evolves along with the rest of packaging.
Instead of attempting to maintain a "mini pip" for the sole purpose of
installing pip the getpip module will, as an implementation detail,
include a private copy of pip and its dependencies which will be used to
discover and install pip from PyPI. It is important to stress that this
private copy of pip is only an implementation detail and it should
not
be relied on or assumed to exist.
Not all users will have network access to PyPI whenever they run the
bootstrap. In order to ensure that these users will still be able to
bootstrap pip the bootstrap will fallback to simply installing the
included
copy of pip. The pip --no-download command line option will be
supported
to force installation of the bundled version, without even attempting to
contact PyPI.
This presents a balance between giving users the latest version of pip, saving them from needing to immediately upgrade pip after bootstrapping it, and allowing the bootstrap to work offline in situations where users might already have packages downloaded that they wish to install.
I still don't understand why this is preferable to just shipping a recent stable pip/setuptools and providing instructions to update post-install. That would surely be a lot simpler not just to implement but for others to understand.
If I'm happy to use the bundled version of pip then why do I need to do anything to make it usable after having already run the installer? If I want the new version then why is 'py -m getpip' better than 'py -m pip install -U pip'?
You don't, the installer bootstraps it for you. Running it explicitly should only be needed when building from source, or bootstrapping a previously pip-free virtual environment.
The complicated bootstrapping dance is both to make pip easy to leave out if people really don't want it and to avoid the CPython platform installers and pip getting into a fight about who is responsible for the files.
Recommendations for Downstream Distributors
A common source of Python installations are through downstream distributors such as the various Linux Distributions [#ubuntu]_ [#debian]_ [#fedora]_, OSX package managers [#homebrew]_, or python specific tools [#conda]_. In order to provide a consistent, user friendly experience to all users of Python regardless of how they attained Python this PEP recommends and asks that downstream distributors:
Ensure that whenever Python is installed pip is also installed.
- This may take the form of separate packages with dependencies on each other so that installing the Python package installs the pip package and installing the pip package installs the Python package.
Do not remove the bundled copy of pip.
Are distros really going to be okay with this idea? Many of them have CPython in their base install so you're basically asking that they always ship a parallel package management system that is outside of their control.
Fedora is fine with it (we discussed it at Flock last month), while Ubuntu (and Debian?) already splits out a "python-core" package for inclusion on the installation media, so should be fine with having the full python have a circular dependency with pip.
Other distros will be free to make their own decisions, but I believe they all already tolerate this bundling approach inside virtualenv.
Windows and Mac OS X users are intended as the main beneficiaries though - bootstrapping pip with yum, apt, etc is much easier than bootstrapping it on either of those platforms.
Personally I think that it's unfortunate that distro package managers don't have a --user option like pip does but I've always assumed that they had some good reason for not wanting any old user to be able to easily install things without admin/root privileges. This would break that arrangement since any user would be able to use 'pip install --user' to install anything from PyPI. I imagine that lots of deployment sites would want to disable this even if the distro has it enabled by default.
Yep, but there are plenty of options available to do that, and the better ones work even if users download and install pip directly.
Our target audience here is the beginning enthusiast (regardless of OS). Sophisticated users (including admins that want to lock their system down) can still do so if they really want to.
Cheers, Nick.
> >
Oscar
Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig
On 16 Sep 2013 21:23, "Antoine Pitrou" antoine@python.org wrote: >
Nick Coghlan <ncoghlan <at> gmail.com> writes: >
On 16 Sep 2013 20:06, "Antoine Pitrou" <antoine <at> python.org> wrote: > >
Hi,
Donald Stufft <donald <at> stufft.io> writes: >
This is also a matter of starting as we mean to
continue: similar
to IDLE
(see PEP 434), getpip will be permanently exempted from the "no
new
features in maintenance releases" restriction, as it will include
(and
rely on) upgraded versions of pip even in maintenance releases.
This sounds rather weird. If the whole point of getpip is for
people to
get the latest pip version without it being bundled, the why does
getpip
itself need to be upgraded in maintenance releases?
(barring bug and compatibility fixes, obviously)
Because getpip contains a complete private copy of pip that it installs
in
the "--no-download" case and otherwise uses to download the latest
version.
Technically you could lock down the getpip shim to prevent feature
additions, but I don't see the point in introducing cross-version
inconsistencies in maintained versions if we decide the shim should expose
more pip features.
Well... Cross-version inconsistencies are the reason we have several maintained versions in the first place.
If you upgrade getpip's functionality in maintenance releases, this means someone with Python 2.7.7 won't get the same experience as, e.g., someone with Python 2.7.6 or 2.7.8. It breaks the expectation that maintenance releases are basically substitutable to each other (modulo, of course, bug fixes). It also makes support more complicated for the various Python communities ("wait, which 2.7 version do you have? then your getpip doesn't have that option, you must instead do this and that...").
Well, people shouldn't be running getpip manually very often in the first place.
The one thing I do not want to preclude is security improvements in maintenance releases. Those may require visible CLI changes (e.g. a flag to opt in to signature checking).
End users should then get the enhanced security automatically most of the time (as the installers and pyvenv pass in the flag), while direct invocations will remain unaltered (as they won't pass the new flag).
The next Python feature release would then make the flag opt-out rather than opt-in.
I'm happy to limit the exception to such security enhancements, though, rather than allowing free reign for arbitrary getpip changes in maintenance releases.
>
It will probably also make Python maintenance more difficult for distributors (e.g. Linux distros) which commit to API stability between bugfix versions.
If the API additions are limited to opt-in security improvements, they can probably live with it (although, to be honest, while I don't work for the Platform team, it wouldn't surprise me if Red Hat still left pip and getpip out of RHEL and only included it in Red Hat Software Collections, regardless of what our recommendations say).
Cheers, Nick.
>
Regards
Antoine.
Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig
Nick Coghlan <ncoghlan <at> gmail.com> writes:
Well, people shouldn't be running getpip manually very often in the first place. The one thing I do not want to preclude is security improvements in maintenance releases. Those may require visible CLI changes (e.g. a flag to opt in to signature checking). End users should then get the enhanced security automatically most of the time (as the installers and pyvenv pass in the flag), while direct invocations will remain unaltered (as they won't pass the new flag).
I definitely agree with this :)
(although, to be honest, while I don't work for the Platform team, it wouldn't surprise me if Red Hat still left pip and getpip out of RHEL and only included it in Red Hat Software Collections, regardless of what our recommendations say).
Yes, I suppose Debian may make the same choice. Distributions like their "minimal" packages :)
Regards
Antoine.
On 16 September 2013 12:27, Nick Coghlan ncoghlan@gmail.com wrote: >
On 16 Sep 2013 19:55, "Oscar Benjamin" oscar.j.benjamin@gmail.com wrote: >
I still don't understand why this is preferable to just shipping a recent stable pip/setuptools and providing instructions to update post-install. That would surely be a lot simpler not just to implement but for others to understand.
If I'm happy to use the bundled version of pip then why do I need to do anything to make it usable after having already run the installer? If I want the new version then why is 'py -m getpip' better than 'py -m pip install -U pip'?
You don't, the installer bootstraps it for you. Running it explicitly should only be needed when building from source, or bootstrapping a previously pip-free virtual environment.
Oh okay. So basically the normal thing is that pip just gets installed automatically when you install Python. For most people the whole of the "explicit bootstrapping" described in the PEP is an implementation detail that occurs implicitly during installation? The only point of relevance from a user perspective is that running the installer without a network connection leaves you with an older version of pip/setuptools.
The complicated bootstrapping dance is both to make pip easy to leave out if people really don't want it and to avoid the CPython platform installers and pip getting into a fight about who is responsible for the files.
Surely this is only relevant for people using the installers since if you're capable of building CPython from source then you should be plenty capable of installing pip/setuptools from source as well. Likewise if you're installing via a distro package manager then you're not going to use this bootstrapping script. If this is just for the Windows and OSX installers then can they not just have a tickbox for installing the bundled pip and another tickbox for updating it (both on by default)? If you need to update it after installation then you can just use pip to update itself.
Who, apart from the Windows and OSX installers, is going to use this bootstrap script?
When you say that pip and the installer could get into a fight about responsibility do you mean for uninstallation? Presumably if you're uninstalling Python then you also want to uninstall the associated pip installation so it's fine for the installer to just delete everything to do with pip anyway right?
Oscar
On 16 September 2013 22:08, Oscar Benjamin oscar.j.benjamin@gmail.com wrote:
On 16 September 2013 12:27, Nick Coghlan ncoghlan@gmail.com wrote: >
On 16 Sep 2013 19:55, "Oscar Benjamin" oscar.j.benjamin@gmail.com wrote: >
I still don't understand why this is preferable to just shipping a recent stable pip/setuptools and providing instructions to update post-install. That would surely be a lot simpler not just to implement but for others to understand.
If I'm happy to use the bundled version of pip then why do I need to do anything to make it usable after having already run the installer? If I want the new version then why is 'py -m getpip' better than 'py -m pip install -U pip'?
You don't, the installer bootstraps it for you. Running it explicitly should only be needed when building from source, or bootstrapping a previously pip-free virtual environment.
Oh okay. So basically the normal thing is that pip just gets installed automatically when you install Python. For most people the whole of the "explicit bootstrapping" described in the PEP is an implementation detail that occurs implicitly during installation? The only point of relevance from a user perspective is that running the installer without a network connection leaves you with an older version of pip/setuptools.
The complicated bootstrapping dance is both to make pip easy to leave out if people really don't want it and to avoid the CPython platform installers and pip getting into a fight about who is responsible for the files.
Surely this is only relevant for people using the installers since if you're capable of building CPython from source then you should be plenty capable of installing pip/setuptools from source as well. Likewise if you're installing via a distro package manager then you're not going to use this bootstrapping script. If this is just for the Windows and OSX installers then can they not just have a tickbox for installing the bundled pip and another tickbox for updating it (both on by default)? If you need to update it after installation then you can just use pip to update itself.
Who, apart from the Windows and OSX installers, is going to use this bootstrap script?
As noted in the PEP, pyvenv will use it to add pip to virtual environments by default (with an option to turn it off when creating the venv). The only case where we expect getpip won't be used is for system installs of Python on Linux distributions (since the system package manager will likely provide it instead).
When you say that pip and the installer could get into a fight about responsibility do you mean for uninstallation? Presumably if you're uninstalling Python then you also want to uninstall the associated pip installation so it's fine for the installer to just delete everything to do with pip anyway right?
No, it's a problem when you install a new maintenance version of CPython over an existing installation. With getpip, we can treat that like any other case of running getpip when pip is already installed. With a bundled pip, the OS installer will try to overwrite the existing installation (which may be a downgrade if you previously used pip to upgrade itself to a more recent version than the bundled one).
Separating the two (installer owns getpip, pip owns pip) makes a lot of competing upgrade related issues just go away.
The other aspect is a social one, though. The bootstrapping dance helps make it clearer that only getpip is developed directly under the normal CPython governance model - pip is developed by PyPA/distutils-sig and merely shipped with CPython.
However, I just noticed that the PEP doesn't currently specify the effect of running "python -m getpip" when pip is already installed. I believe it should attempt to upgrade pip, so that in the normal course of events (i.e. just installing CPython maintenance releases without manually upgrading pip), then pip will be automatically upgraded to the latest version each time CPython itself is updated.
Cheers, Nick.
-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia
On Sep 16, 2013, at 7:27 AM, Nick Coghlan ncoghlan@gmail.com wrote:
Other distros will be free to make their own decisions, but I believe they all already tolerate this bundling approach inside virtualenv.
Going through this thread but just wanted to mention i've heard positive things from a few people involved in FreeBSD too. Not a certain +1 but a general willingness to figure something out.
Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
On Sep 16, 2013, at 8:08 AM, Oscar Benjamin oscar.j.benjamin@gmail.com wrote:
Oh okay. So basically the normal thing is that pip just gets installed automatically when you install Python. For most people the whole of the "explicit bootstrapping" described in the PEP is an implementation detail that occurs implicitly during installation? The only point of relevance from a user perspective is that running the installer without a network connection leaves you with an older version of pip/setuptools.
Yes, ideally a user will never have to invoke it manually. However we can't control what the downstream distributors do so for some Linux versions they may have to invoke it (or use system packages if pip is there).
It also works as a nice fallback if you somehow end up with pip uninstalled on a system that doesn't have something like apt-get to get it back.
And yes by default the online/offline stuff is behind the scenes for the typical user and they'll get the latest version of pip during install that we can locate.
Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
On Sep 16, 2013, at 10:15 AM, Nick Coghlan ncoghlan@gmail.com wrote:
However, I just noticed that the PEP doesn't currently specify the effect of running "python -m getpip" when pip is already installed. I believe it should attempt to upgrade pip, so that in the normal course of events (i.e. just installing CPython maintenance releases without manually upgrading pip), then pip will be automatically upgraded to the latest version each time CPython itself is updated.
TBH I just assumed it would say that pip is already bootstrapped, but I'm
OK with making it upgrade as well. My thinking was if you already had
pip then pip install --upgrade pip is easier but making the bootstrap
upgrade too does mean that installing a maintenance release will upgrade
your pip too which is kinda nice.
Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
On 17 September 2013 12:21, Donald Stufft donald@stufft.io wrote: >
On Sep 16, 2013, at 10:15 AM, Nick Coghlan ncoghlan@gmail.com wrote:
However, I just noticed that the PEP doesn't currently specify the effect of running "python -m getpip" when pip is already installed. I believe it should attempt to upgrade pip, so that in the normal course of events (i.e. just installing CPython maintenance releases without manually upgrading pip), then pip will be automatically upgraded to the latest version each time CPython itself is updated.
TBH I just assumed it would say that pip is already bootstrapped, but I'm
OK with making it upgrade as well. My thinking was if you already had
pip then pip install --upgrade pip is easier but making the bootstrap
upgrade too does mean that installing a maintenance release will upgrade
your pip too which is kinda nice.
Yeah, that's the exact same thought process I went through :)
Cheers, Nick.
-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia
On 16 September 2013 18:07, anatoly techtonik techtonik@gmail.com wrote:
On Sun, Sep 15, 2013 at 6:33 PM, Donald Stufft donald@stufft.io wrote:
So there've been a number of updates to PEP453, so i'm posting it here again for more discussion:
Just want to say that It is good to see that over three year pip
has
gained strength to be the tool of choice for Python package
management. My attempt to propose this three years ago had failed,
because there was no package management tool people could agree to,
even though the proposal was for the interactive user script that
could recommend all :
https://mail.python.org/pipermail/distutils-sig/2010-March/015894.html
So, why PIP?
The design of pip is heavily based around addressing various issues with the design of easy_install, while still providing equivalent functionality. The last big missing piece was an updated alternative to the binary egg format that supported FHS compliant installation, and that was addressed in pip 1.4 with the initial version of pip's wheel support.
The amicable resolution of the setuptools/distribute split (with distribute merging back into setuptools and development moving to the PyPA account on BitBucket) also makes it easier for python-dev to officially bless pip as the default installation tool, which people can use unless/until they need something with more sophisticated handling of external dependencies (like zc.buildout or conda).
Cheers, Nick.
-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia
-
Alex Burke -
anatoly techtonik -
Antoine Pitrou -
Donald Stufft -
Nick Coghlan -
Oscar Benjamin -
Paul Moore