[CentOS-devel] URLs in centos-release-<sig> packages: /altarch vs. /centos/

Tue Mar 6 14:34:18 UTC 2018
Fabian Arrotin <arrfab at centos.org>

On 06/03/18 13:21, Murilo Opsfelder Araujo wrote:
> On 03/06/2018 03:11 AM, Brian Stinson wrote:
>> Hi Folks,
>>
>> Now that we have SIG Content in the /altarch directories for CentOS 7 on the
>> mirrors, we need to come with some requirements and recommendations for dealing
>> with the different locations. 
>>
>> tl;dr The current thinking is to add the following snippet in the %post of
>> centos-release and release to all of the arches. This will set a yum var to the
>> correct content location when a new system gets installed: 
>>
>>     `uname -m | grep -q 'x86_64'  && echo 'centos' >/etc/yum/vars/contentdir || echo 'altarch' >/etc/yum/vars/contentdir`
>>
>> Here's the start of a proposal from the SIG perspective
>>
>> ## Requirements:
>>
>> - The same noarch binary RPM *must* be distributable to the Extras
>>   repo for each architecture
>>
>> - The centos-release-<SIG> packages *must* require centos-release
>>
>>
>> ## New Recommendations for creating a centos-release file:
>>
>> - A yum variable called 'contentdir' will be populated with the toplevel
>>   directory for SIGs to use
>>
>> 1.) Modify baseurls in the SIG repo files to look like the following (using
>> openstack-queens as an example):
>>
>>
>>  [centos-openstack-queens]
>>  name=CentOS-7 - OpenStack queens
>>  baseurl=https://mirror.centos.org/$contentdir/cloud/$basearch/openstack-queens/
>>  gpgcheck=1
>>  enabled=1
>>  gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-Cloud
>>  exclude=sip,PyQt4
>>
>>
>> ## Discussion
>>
>> I'd like to hear thoughts, additions, and subtractions here before we update
>> the SIGGuide and rework centos-release. 
>>
>> Cheers!
>>
>>
> 
> Hi, Brian.
> 
> I don't have the whole background of why non-x86_64 architectures are
> placed at /altarch. Perhaps you or someone else from CentOS can provide
> some of the details.
> 
> Wouldn't it be simpler if a non-x86_64 architecture was just another
> directory on, for example, /centos/7/<content>/<arch> hierarchy?
> 
> This also simplifies packaging.
> 
> Cheers
> Murilo

The approach given by Brian isn't rocket science and would permit to
cover that /altarch/ vs /centos/ difference for baseurl=  , that's also
more or less what we use for armhfp , to redirect the kernel repo to
correct one, so it's just a one liner snippet in the .spec for the
-release noarch pkg :-)

WRT difference in the URI, it was a decision taken by KB and Jim when
the first altarch (aarch64) landed on mirror.centos.org, and then we
continued with it , as it also added more content/storage, and some
external mirrors weren't keen on adding all those arches.
That's the reason why they can then do an "opt-in" for those if they want :
 - https://www.centos.org/download/mirrors/
 - https://www.centos.org/download/altarch-mirrors/

Does that answer your question ?

-- 
Fabian Arrotin
The CentOS Project | https://www.centos.org
gpg key: 56BEC54E | twitter: @arrfab

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