PR#903: Update Python guidelines for Fedora 31 - packaging-committee

packaging-committee

#903 Update Python guidelines for Fedora 31

Merged 5 years ago by churchyard. Opened 5 years ago by churchyard.

churchyard/packaging-committee python_rpm4.15 into master

https://fedoraproject.org/wiki/Changes/Python_means_Python3

Miro Hrončok • 5 years ago

fe68176

Update the %__python macro documentation after RPM 4.15

Miro Hrončok • 5 years ago

745fa2b

guidelines/modules/ROOT/pages/Python.adoc

file modified

+7 -5

		`@@ -19,7 +19,8 @@`

		`== Multiple Python Runtimes`

		- For backwards compatibility, `/usr/bin/python` is, if it is installed, a symbolic link to `/usr/bin/python2`.
		+ Since Fedora 31 `/usr/bin/python` is, if it is installed, a symbolic link to `/usr/bin/python3`.
		+ It was a symbolic link to `/usr/bin/python2` on previous releases.

		Packages in Fedora MUST NOT use `/usr/bin/python`. Instead packages for Python 3 MUST use `/usr/bin/python3` (even if upstream supports both Python 2 and 3). As a result of that `/usr/bin/python` (as well as `/usr/bin/env python` and similar) MUST NOT be used in shebang lines or as a dependency of a package. As of Fedora 30, all uses of unversioned python executables in shebang lines will fail the build.
		`These shebangs MUST be fixed. If it is necessary to disable the checks, please see the information in xref:index#_shebang_lines[Shebang lines].`
		`@@ -116,13 +117,14 @@`

		`=== The %python_provide macro`

		- In order to make the switch from Python 2 to Python 3 automatic, all packages that provide `+python3-%{srcname}+` (for any `+%{srcname}+`) SHOULD use the `+%python_provide+` macro with the package name, for example:
		+ All packages that provide `+python3-%{srcname}+` (for any `+%{srcname}+`) SHOULD use the `+%python_provide+` macro with the package name, for example:

		`----`
		`%{?python_provide:%python_provide python3-%{srcname}}`
		`----`

		- This eases distribution-wide renaming of Python packages. (For example, in the future a virtual provide of `+python-%{srcname}+` might become appropriate for Python 3 libraries. In that case, `+%python_provide+` will be changed to add it.) Packages that do not include this macro would need to be adapted to such changes manually.
		+ In Fedora 31 and further, it adds a virtual provide of `+python-%{srcname}+` for Python 3 libraries.
		`+ For previous releases, it used to add the virtual provide for Python 2 libraries.`

		`== Automatic Provides with a standardized name`

		`@@ -175,8 +177,8 @@`
		`\|Notes`

		\|`+%{__python}+`
		- \|`+/usr/bin/python+`
		`- \|Prohibited (see note below).`
		+ \|`+/usr/bin/python+` (for backwards compatibility)
		+ \|Don't use this macro without redefining it. Defining is changes the meaning of other "unversioned" Python macros such as `+%{python_sitelib}+`.

		\|`+%{__python3}+`
		\|`+/usr/bin/python3+`

guidelines/modules/ROOT/pages/Python_Appendix.adoc

file modified

+3 -4

		`@@ -334,10 +334,9 @@`

		`* If only one executable is to be shipped, then it owns its own slot and should use /usr/bin/python3.`
		`* If executables are to be shipped for both python 2 and python 3:`
		`- ** Both python 2 and python 3 variants must provide symlinks with a '-X' and '-X.Y' suffix (python runtime major version, or python runtime major.minor version), unless upstream already provides appropriately versioned executables without the dash.`
		`- ** The unversioned executable should be the python3 version, unless it would break users expectations, in that case it may be the python2 version.`
		- ** For example, the python3 version of "twisted" must ship executables `+/usr/bin/twistd-3+` and `+/usr/bin/twistd-3.7+` (assuming python3 is currently version 3.7) and it should ship `+/usr/bin/twistd+`; while the python2 version must provide `+/usr/bin/twistd-2+` and `+/usr/bin/twistd-2.7+`.
		- ** As an example of the exception, users might except that the `+ipython+` command will run the same Python version as `+python+`.
		`+ ** Both python 2 and python 3 variants MUST provide symlinks with a '-X' and '-X.Y' suffix (python runtime major version, or python runtime major.minor version), unless upstream already provides appropriately versioned executables without the dash.`
		`+ ** The unversioned executable MUST be the python3 version.`
		+ ** For example, the python3 version of "twisted" MUST ship executables `+/usr/bin/twistd-3+` and `+/usr/bin/twistd-3.7+` (assuming python3 is currently version 3.7) and `+/usr/bin/twistd+`; while the python2 version MUST provide `+/usr/bin/twistd-2+` and `+/usr/bin/twistd-2.7+`.
		** For compatibility packages, the Python version is appended after the specific package version, for example `+/usr/bin/coverage-v1.2-3+` and `+/usr/bin/coverage-v1.2-3.4+` for python3-coverage1.2 compat package.

		`=== Running 2to3 from the spec file`

no initial comment

churchyard commented 5 years ago

(This is not yet true.)

tibbs commented 5 years ago

Technically I guess we should mention that (with the current PR against python-rpm-macros) attempting to use %__python will result in an error parsing the specfile.

churchyard commented 5 years ago

I agree. Marking this WIP.