On Fri, Aug 21, 2015 at 2:51 AM, Nick Coghlan <ncoghlan@gmail.com> wrote:
On 21 August 2015 at 05:58, Robert Collins <robertc@robertcollins.net> wrote:
> On 21 August 2015 at 07:25, Donald Stufft <donald@stufft.io> wrote:
>>
>> On August 20, 2015 at 3:23:09 PM, Daniel Holth (dholth@gmail.com) wrote:
>>> If you need that for some reason just put the longer information in the
>>> metadata, inside the WHEEL file for example. Surely "does it work on my
>>> system" dominates, as opposed to "I have a wheel with this mnemonic tag,
>>> now let me install debian 5 so I can get it to run".
>>>
>>>
>>
>> It’s less about “now let me install Debian 5” and more like tooling that doesn’t run *on* the platform but which needs to make decisions based on what platform a wheel is built for.
>
> Cramming that into the file name is a mistake IMO.
>
> Make it declarative data, make it indexable, and index it. We can do
> that locally as much as via the REST API.
>
> That btw is why the draft for referencing external dependencies
> specifies file names (because file names give an ABI in the context of
> a platform) - but we do need to identify the platform, and
> platform.distribution should be good enough for that (or perhaps we
> start depending on lsb-release for detection

LSB has too much stuff in it, so most distros aren't LSB compliant out
of the box - you have to install extra packages.

/etc/os-release is a better option:
http://www.freedesktop.org/software/systemd/man/os-release.html

As per this discussion, and because I've discovered that the entire platform module is deprecated in 3.5 (and other amusements, like a Ubuntu-modified version of platform that ships on Ubuntu - platform as shipped with CPython detects Ubuntu as debian), I'm switching to os-release, but even that is unreliable - the file does not exist in CentOS/RHEL 6, for example. On Debian testing/sid installs, VERSION and VERSION_ID are unset (which is not wrong - there is no release of testing, but it does make identifying the platform more complicated since even the codename is not provided other than at the end of PRETTY_NAME). Regardless of whether a hash or a human-identifiable string is used to identify the platform, there still needs to be a way to reliably detect it.

Unless someone tells me not to, I'm going to default to using os-release and then fall back to other methods in the event that os-release isn't available, and this will be in some sort of library alongside pep425tags in wheel/pip.

FWIW, os-release's `ID_LIKE` gives us some ability to make assumptions without explicit need for a binary-compatibility.cfg (although not blindly - for example, CentOS sets this to "rhel fedora", but of course RHEL/CentOS and Fedora versions are not congruent).

--nate
 


My original concern with using that was that it *over*specifies the
distro (e.g. not only do CentOS and RHEL releases show up as different
platforms, but so do X.Y releases within a series), but the
binary-compatibility.txt idea resolves that issue, since a derived
distro can explicitly identify itself as binary compatible with its
upstream and be able to use the corresponding wheel files.

Regards,
Nick.

--
Nick Coghlan   |   ncoghlan@gmail.com   |   Brisbane, Australia
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