PEP 715: Disabling bdist_egg distribution uploads on PyPI (#3161)

Signed-off-by: William Woodruff <william@yossarian.net>
Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>

.github/CODEOWNERS

@@ -595,6 +595,7 @@ pep-0711.rst  @njsmith
 pep-0712.rst  @ericvsmith
 pep-0713.rst  @ambv
 pep-0714.rst  @dstufft
+pep-0715.rst  @dstufft
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pep-0715.rst

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+PEP: 715
+Title: Disabling bdist_egg distribution uploads on PyPI
+Author: William Woodruff <william@yossarian.net>
+Sponsor: Donald Stufft <donald@stufft.io>
+PEP-Delegate: Donald Stufft <donald@stufft.io>
+Status: Draft
+Type: Process
+Topic: Packaging
+Content-Type: text/x-rst
+Created: 06-Jun-2023
+Post-History:
+Resolution:
+
+Abstract
+========
+
+This PEP recommends deprecating and then disabling new uploads of the
+``bdist_egg`` distribution type on PyPI. In a parallel move, this PEP recommends
+deprecating and then disabling new uploads of distribution filenames that have
+the ``.egg`` suffix.
+
+It does not recommend removing or otherwise affecting any previously
+uploaded ``bdist_egg`` distributions or files with the ``.egg`` suffix.
+
+Rationale
+=========
+
+Previous Work
+-------------
+
+The groundwork for this proposal was established with :pep:`527`, which
+proposed deprecating and eventually removing upload support for a handful
+of un(der)used file extensions and distribution types.
+
+In particular, :pep:`527` proposed the removal of the ``bdist_dumb``,
+``bdist_rpm``, ``bdist_dmg``, ``bdist_msi``, and ``bdist_wininst`` distribution
+types, as well as the ``.tar``, ``.tar.bz2``, ``.tar.xz``, ``.tar.Z``,
+``.tgz``, and ``.tbz`` file extensions on distribution filenames.
+
+:pep:`527` was fully enacted with
+`PR #7529 <https://github.com/pypi/warehouse/pull/7529>`_ to Warehouse,
+which was merged on 13 April 2020.
+
+The ``bdist_egg`` format
+------------------------
+
+The ``bdist_egg`` filetype identifies distributions in the
+:term:`egg format <packaging:Egg>`. The
+egg format was introduced by setuptools in 2004 and is roughly equivalent
+in functionality to the
+:term:`wheel format <packaging:Wheel>`
+first introduced by :pep:`427` in 2012
+as :ref:`the standardized format <packaging:binary-distribution-format>`
+for :term:`packaging:Built Distributions`.
+
+Despite its longevity, the egg format has had
+`limited adoption on PyPI <https://github.com/pypi/warehouse/issues/10653>`_.
+Some observations from that issue:
+
+* In the month of May 2023, ``bdist_egg`` uploads accounted for 0.2% of all
+  distribution uploads to PyPI;
+* ``pip`` deprecated its ``--egg`` option in 2016;
+* ``setuptools`` has considered egg support deprecated since 2019;
+* ``build`` only supports the ``sdist`` and ``bdist_wheel`` filetypes.
+
+Given the above, this PEP proposes the removal of the ``bdist_egg`` format
+under the same justifications presented in :pep:`527`, namely:
+
+* Egg distributions are of of limited use to the broader ecosystem and
+  therefore represent a non-reciprocal maintenance burden;
+* Having an additional built distribution format
+  is confusing to end users, who may
+  mistakenly pick it over the wheel format;
+
+This PEP *additionally* offers an argument for removal rooted in
+standardization and duplication: the egg format is not standardized by any
+PEP or other community standard, and overlaps heavily with its standardized
+and well-supported alternative (wheel).
+
+The ``.egg`` file extension
+---------------------------
+
+The ``.egg`` file extension is used exclusively for distributions of the
+``bdist_egg`` format. As such, it serves no purpose in a scenario where
+PyPI disables new distribution uploads for ``bdist_egg`` distributions.
+
+Removal Process
+===============
+
+This PEP does **NOT** propose removing any existing files from PyPI, only
+disallowing new ones from being uploaded.
+
+PyPI will provide a deprecation period of one month. At the beginning
+of the deprecation period, maintainers of projects that have uploaded one or
+more egg distributions since 1 Jan 2023 will receive a one-time email informing
+them of the upcoming end of support for egg distribution uploads.
+
+During the deprecation period, users will continue to be allowed to upload egg
+distributions to new and existing projects. Uploading an egg distribution
+during this period will also send all maintainers of the project
+a similar email as above, reminding them of the upcoming end of support.
+
+After the deprecation period, support for uploading egg distributions will
+cease to exist on PyPI.
+
+Prior Art
+---------
+
+The removal process above was based on that of :pep:`527`, with the following
+changes:
+
+* All projects will be continue to be allowed to upload eggs
+  during the deprecation period, not just those that have done so previously.
+* Uploading an egg during the deprecation period will also trigger an email
+  to maintainers, in addition to the one-time email at the beginning.
+
+Backwards Compatibility
+=======================
+
+Limited Impact
+--------------
+
+As noted in the rationale section, this PEP is expected to have no impact
+on the overwhelming majority of PyPI users and projects, and there has been
+`substantial community coordination <https://github.com/pypi/warehouse/issues/10653>`_
+over the past 1 1/2 years to minimize the impact on the few last use cases.
+
+Hosted Files
+------------
+
+This PEP does **NOT** propose the removal of any egg distributions that have
+already been uploaded to PyPI. All previously uploaded egg distributions will
+remain downloadable, ensuring that existing users will continue to be able
+to download them.
+
+Deprecation Period
+------------------
+
+This PEP uses the removal process documented above, which specifies
+a deprecation period of 1 month for projects that have previously uploaded
+egg distributions to PyPI.
+
+After the end of the deprecation period, support for uploading new egg
+distributions will cease to exist on PyPI.
+
+Security Implications
+=====================
+
+This PEP does not identify any positive or negative security implications
+associated with removing upload support for egg distributions.
+
+How To Teach This
+=================
+
+As part of the removal process, PyPI will send emails to all maintainers of
+projects that have previously uploaded egg distributions in 2023.
+
+Additionally, PyPI will write a post on the
+`PyPI blog <https://blog.pypi.org/>`_ that publicly announces the deprecation
+period's start and end.
+
+Copyright
+=========
+
+This document is placed in the public domain or under the
+CC0-1.0-Universal license, whichever is more permissive.