Add platform.freedesktop_os_release()

[tiran]

BPO	28468
Nosy	@malemburg, @warsaw, @doko42, @vstinner, @tiran, @bitdancer, @asvetlov, @pmp-p, @matrixise, @stratakis, @pablogsal, @miss-islington
PRs	bpo-28468: Add platform.freedesktop_osrelease #23492 bpo-28468: Fix typo in _os_release_candidates #23913

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-11-30.21:37:48.382>
created_at = <Date 2016-10-18.08:47:38.710>
labels = ['type-feature', 'library', '3.10']
title = 'Add platform.freedesktop_os_release()'
updated_at = <Date 2020-12-23.16:36:03.116>
user = 'https://github.com/tiran'

bugs.python.org fields:

activity = <Date 2020-12-23.16:36:03.116>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2020-11-30.21:37:48.382>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2016-10-18.08:47:38.710>
creator = 'christian.heimes'
dependencies = []
files = []
hgrepos = []
issue_num = 28468
keywords = []
message_count = 62.0
messages = ['278847', '278849', '278850', '278851', '278860', '278861', '278862', '278863', '278864', '278865', '278868', '278869', '278871', '278874', '381719', '381721', '381722', '381724', '381726', '381727', '381728', '381729', '381730', '381733', '381734', '381735', '381736', '381737', '381741', '381742', '381743', '381744', '381745', '381747', '381750', '381757', '381758', '381768', '381798', '381799', '381804', '381805', '381808', '381812', '381813', '381814', '381816', '381817', '381819', '381820', '381825', '381849', '381851', '381855', '381856', '382181', '382184', '382194', '382195', '382196', '382197', '383649']
nosy_count = 12.0
nosy_names = ['lemburg', 'barry', 'doko', 'vstinner', 'christian.heimes', 'r.david.murray', 'asvetlov', 'pmpp', 'matrixise', 'cstratak', 'pablogsal', 'miss-islington']
pr_nums = ['23492', '23913']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue28468'
versions = ['Python 3.10']

[tiran]

bpo-1322 has deprecated platform.linux_distribution(). The feature is going to be removed without replacement functions in the stdlib. It's no longer possible to detect the Linux distribution from stdlib. Let's add a function to read /etc/os-release [1] instead. It's a very simple format and pretty standard for many years.

[1] http://0pointer.de/blog/projects/os-release

[matrixise]

and for the older distributions without Systemd ? What do you suggest ?

[stratakis]

Also there is an external project now aiming to provide this functionality:

https://github.com/nir0s/distro

[tiran]

I'm not suggesting a generic platform detection function but rather a limited function just for os-release. On platforms without /etc/os-release the function should obviously fail and raise an exception.
/etc/os-release is available on distributions without systemd. Even my oldest Debian installation on a Raspberry Pi has it.

A large majority of Linux distributions has the file. It's available on Debian, Fedora, RHEL 6+, Ubuntu 14.04+ and many more.

[doko42]

-1

This is not available everywhere, not even on Linux distributions. Why would you implement something which only works on 50% of existing Linux distributions? Who would even use that? And for what would you use it? You have a distro module available now from PyPi, you can use that one instead, and it gives 100% correct results for all currently known distros, and can be updated independent of Python releases.

If it's that a simple function, then please implement it for your own needs. I think it's bad style too, to rely on specific distro and release information instead of checking release names and versions. Such a style should not be encouraged in the standard lib from my point of view.

[vstinner]

Can you elaborate the expected API? /etc/os-release is not a single line, but a list of variables. Example on my Fedora 24:
---

$ cat /etc/os-release 
NAME=Fedora
VERSION="24 (Workstation Edition)"
ID=fedora
VERSION_ID=24
PRETTY_NAME="Fedora 24 (Workstation Edition)"
ANSI_COLOR="0;34"
CPE_NAME="cpe:/o:fedoraproject:fedora:24"
HOME_URL="https://fedoraproject.org/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=24
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=24
PRIVACY_POLICY_URL=https://fedoraproject.org/wiki/Legal:PrivacyPolicy
VARIANT="Workstation Edition"
VARIANT_ID=workstation

---

I think that you should return a dictionary key=>value. Maybe we can simply return an empty dictionary if the file doesn't exist or cannot be read (but raise an error on parsing error).

FYI On Fedora 24, /etc/os-release is in fact a symbolic link to a symbolic link:
---

$ ls -l /etc/os-release 
lrwxrwxrwx. 1 root root 21 24 juin  03:25 /etc/os-release -> ../usr/lib/os-release

$ ls -l /usr/lib/os-release
lrwxrwxrwx. 1 root root 37 13 sept. 09:51 /usr/lib/os-release -> ./os.release.d/os-release-workstation

$ ls -l /usr/lib/os.release.d/os-release-workstation
-rw-r--r--. 1 root root 518 24 juin  03:25 /usr/lib/os.release.d/os-release-workstation

---

See also systemd manual page:
https://www.freedesktop.org/software/systemd/man/os-release.html

[vstinner]

"This is not available everywhere, not even on Linux distributions. Why would you implement something which only works on 50% of existing Linux distributions?"

According to http://0pointer.de/blog/projects/os-release systemd requires /etc/os-release. Since all major Linux distribution now use systemd, it makes sense to me to add such function.

We can document that the feature is specific to Linux (or don't declare the function on Linux?), document that it only works on recent versions of Linux distributions, and document that it doesn't work on all Linux distributions.

[tiran]

Please read the title of this issue. It is "Add platform.linux_os_release()". The name of the function clearly indicats that the function only works on Linux with a os-release file.

[doko42]

"Since all major Linux distribution now use systemd, it makes sense to me to add such function."

I'm not aware of any embedded Linux distro using systemd (no, I don't consider Raspian an embedded Linux distro).

[doko42]

"The name of the function clearly indicats that the function only works on Linux with a os-release file."

No, it does not. That would be linux_distribution_with_os_release_file().

[bitdancer]

I hate systemd. So does the company I'm currently doing most of my work for. We're using centos6 because it doesn't have systemd. I personally use gentoo without systemd.

That said, I don't use the platform module, so this doesn't actually affect me.

[tiran]

ETOOMUCHBIKESHEDDING and another uncalled systemd flame wars.