[Distutils] CentOS5 is EOL, impact on manylinux1?

[Nathaniel Smith]

On Wed, Apr 5, 2017 at 2:37 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> On 5 April 2017 at 15:59, Nathaniel Smith <njs at pobox.com> wrote:
>> On Tue, Apr 4, 2017 at 10:10 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>>> It may also be worth getting in touch with the CentOS CI folks about
>>> those aspects: https://wiki.centos.org/QaWiki/CI/GettingStarted
>>
>> That page seems to say that for CentOS 7 they only support x86_64?
>
> Sorry, I should have spelled out that chain of logic more clearly:
>
> - ppc64le machines aren't that easy to come by, especially in public
> cloud services
> - a build approach based on ppc64le VMs running on x86_64 hosts is
> likely to be easier to manage
> - that means the desired CI service feature is "run arbitrary VMs",
> rather than "bare metal ppc64le systems"
>
> You can kinda sorta do that to a limited degree in Travis, but our
> experience was that the CentOS Vagrant boxes didn't work by default,
> so we asked the CentOS CI maintainers what our options might be over
> there.
>
> And as it turns out, not only are we able to get bare metal machines
> to run our VMs on (rather than messing about with nested virt
> support), but the CentOS boxes are pre-cached on the local network, so
> they should be pretty quick to download (we haven't actually got our
> CI up and running yet, so I won't be able to vouch for that personally
> until we do).

I think bare metal access only matters for running x86 with hardware
accelerated virtualization? If we want to emulate a totally different
architecture like ppc64le then IIUC qemu does that as a regular
user-space program. You definitely can run qemu in this mode on
travis-ci, e.g. check out all the virtual architectures that rust
builds on:

   https://travis-ci.org/rust-lang/rust/

So I think travis-ci and centos-ci are equivalent on this axis – if we
want to go the qemu route, then either works, and if we don't, then
neither works?

For me the big question is whether emulation is actually a good idea.
When rust announced their plans I remember seeing some skepticism
about whether one can really trust emulated machines for this kind of
use case, though I can't find it again now... but it's definitely true
that all the major distributions go to great lengths to use real
hardware in their build farms, despite the obvious drawbacks (not just
in terms of maintenance, but also the ongoing pain of using tiny
little arm and mips machines that take dozens of hours to build
things). They know a whole lot more about this than I do so I assume
they have *some* reason :-).

It might be useful to get in touch with some of the distro's ppc64le
wranglers to get their opinion, if anyone knows any of them...

-n

-- 
Nathaniel J. Smith -- https://vorpus.org