Changes/Platform Python Stack

System Python Stack

Summary

A revisit of the System Python change from Fedora 24. System Python will be a separate stack fo Python packages aimed to provide all necessary dependencies to run and build dnf. In Fedora 27 this will be Python 3.6 (same version as python3, but this might change in the future with the Modularity effort).

Owner

• Name: Miro Hrončok
• Email: <python-maint at redhat.com>
• Release notes owner:

Current status

• Targeted release: Fedora 27
• Last updated: 2017-06-30
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

The changes made during the System Python change from Fedora 24 will be reverted.

A new system-python (source) package will be created as a copy of python3 package. Unlike python3, it will be changed so that:

• the location of files will not be /usr/lib/python3.6/ but /usr/lib/system-python/
  • the script that generates the python(abi) requirement will be adapted to generate system-python(abi) requirement for that location
• the location of the binary will be /usr/libexec/system-python
• all the macros will use the system python binary and will be renamed
• all subpackages will be named system-python-*
• the debug build will be disabled
• the modules that are (before this change) not part of system-python-libs but rather python3-libs will relocate to system-python-libs-devel to be available only on build-time
• system-python-libs will provide system-python(abi) instead of python(abi)

Several packages will introduce a new system-python- subpackage. Example specfile of such package:

%global pypi_name foo

Name:           python-%{pypi_name}
Version:        0.13
Release:        1%{?dist}
Summary:        Python %{pypi_name} module

License:        GPLv2
URL:            https://github.com/fedora-python/%{pypi_name}
Source0:        https://files.pythonhosted.org/packages/source/f/%{pypi_name}/%{pypi_name}-%{version}.tar.gz

BuildRequires:  python2-devel
BuildRequires:  python2-setuptools

BuildRequires:  python3-devel
BuildRequires:  python3-setuptools

BuildRequires:  system-python-devel
BuildRequires:  system-python-setuptools

BuildArch:      noarch

%description
...

%package -n     python2-%{pypi_name}
Summary:        %{summary}
Requires:       python2-bar
%{?python_provide:%python_provide python2-%{pypi_name}}

%description -n python2-%{pypi_name}
...

%package -n     python3-%{pypi_name}
Summary:        %{summary}
Requires:       python3-bar
%{?python_provide:%python_provide python3-%{pypi_name}}

%description -n python3-%{pypi_name}
...


%package -n     system-python-%{pypi_name}
Summary:        %{summary}
Requires:       system-python-bar

%description -n system-python-%{pypi_name}
...


%prep
%autosetup -n %{pypi_name}-%{version}


%build
%py2_build
%py3_build
%sypy_build

%install
%py2_install
rm %{buildroot}%{_bindir}/%{pypi_name}

%sypy_install
rm %{buildroot}%{_bindir}/%{pypi_name}

%py3_install


%check
export PYTHONPATH=%{buildroot}%{python2_sitelib}
%{__python2} -m unittest discover -v

export PYTHONPATH=%{buildroot}%{python3_sitelib}
%{__python3} -m unittest discover -v

export PYTHONPATH=%{buildroot}%{systempython_sitelib}
%{__systempython} -m unittest discover -v


%files -n python2-%{pypi_name}
%doc README.rst CHANGES.rst
%license COPYING
%{python2_sitelib}/%{pypi_name}.so
%{python2_sitelib}/%{pypi_name}-%{version}-py?.?.egg-info

%files -n python3-%{pypi_name}
%doc README.rst CHANGES.rst
%license COPYING
%{_bindir}/%{pypi_name}
%{python3_sitelib}/%{pypi_name}.cpython-%{python3_version_nodots}*.so
%{python3_sitelib}/%{pypi_name}-%{version}-py?.?.egg-info

%files -n system-python-%{pypi_name}
%doc README.rst CHANGES.rst
%license COPYING
%{systempython_sitelib}/%{pypi_name}.cpython-%{systempython_version_nodots}*.so
%{systempython_sitelib}/%{pypi_name}-%{version}-py?.?.egg-info

%changelog
...

Benefit to Fedora

With the Modularity effort a minimal stack of Python only needed to run dnf is needed to be part of the Platform. Changing System Python to be a separate stack will allow us to do that.

Scope

• Proposal owners:
  • identify a list of runtime and build dependencies of dnf
  • create a system-python source package
  • change the script that generates the python(abi) requirements to also generate system-python(abi) requirements
  • revert system-python related things from the python3 package
  • add a system-python- subpackage to identified list of packages
  • switch dnf to use that stack

• Other developers: N/A (not a System Wide Change)

• Release engineering: #Releng issue number (a check of an impact with Release Engineering is needed)
  • List of deliverables: N/A (not a System Wide Change)

• Policies and guidelines: N/A (not a System Wide Change)

• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

N/A (not a System Wide Change)

How To Test

N/A (not a System Wide Change)

User Experience

Nothing should change for the user, except a slightly larger amount of packages will be installed on the system.

Dependencies

N/A (not a System Wide Change)

Contingency Plan

• Contingency mechanism: (What to do? Who will do it?) N/A (not a System Wide Change)
• Contingency deadline: N/A (not a System Wide Change)
• Blocks release? No (not a System Wide Change)
• Blocks product? No

If not done on time: Keep dnf running on python3. Finish the work in time of Fedora 28.

If proven not to work as designed: Retire system-python package and remove all the system-python- subpackages. Provide/obsolete system-python- subpackages from their python3- counterparts.

Documentation

N/A (not a System Wide Change)