[CentOS-devel] Using mirrorlist in centos-release-* packages

Hi, as mentioned in 
https://lists.centos.org/pipermail/centos-devel/2018-September/016949.html 
mirrorlist.centos.org has been updated to produce mirror lists for SIG 
content as well. Some centos-release-* packages have already been 
modified to use mirrorlist.centos.org instead of mirror.centos.org, but 
many still point to mirror.centos.org.

Most of mirror.centos.org hosts are also used for seeding the 600+ 
external mirrors we have. By directing some of their download traffic to 
external mirrors we can offer faster sync speeds for those external 
mirrors, and for people downloading individual rpms from 
mirror.centos.org. Second, most of those external mirrors offer faster 
download speeds to end users than what could be achieved by downloading 
from mirror.centos.org, so the users will benefit from this change as 
well. The better geographical coverage does not hurt either. 
mirror.centos.org nodes are donated servers, and it would be kind to the 
sponsors to use their bandwidth sparingly.

The .repo files should be modified so that the current baseurl line gets 
commented out and a mirrorlist entry gets added, like this:

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=storage-gluster-4.1
#baseurl=http://mirror.centos.org/$contentdir/$releasever/storage/$basearch/gluster-4.1/

Note that mirrorlist.c.o can automatically choose between main and 
altarch content based on the arch parameter. The repo names are 
constructed from the repository path by stripping away the architecture 
and changing any slashes to dashes: sclo/x86_64/rh -> sclo-rh, 
sclo/x86_64/sclo -> sclo-sclo, paas/x86_64/openshift-origin311 -> 
paas-openshift-origin311, storage/x86_64/gluster-5 -> storage-gluster-5 
etc. You can use 'curl' to check what mirrorlist outputs for your 
repository.

New repos are added to mirrorlist.centos.org automatically once the 
repository hits mirror.centos.org. That script is currently run every 
three hours. I guess it could be run more frequently (it's fairly 
lightweight), but you should give the external mirrors a few hours to 
sync before announcing your release anyway.

You can either submit an update to your current centos-release-* file 
now, or wait until you need to create a new centos-release-* package for 
other reasons such as releasing softwarepackage-(version+1) which uses 
different paths. My recommendation would be to submit an update to your 
current centos-release-* package, so that you would not need to worry 
about this when you eventually need to publish a new one for other 
reasons. We released an updated centos-release package for CentOS 
AltArch before 7.6.1810 was released for this exact reason, ie. we 
didn't need to worry about this change at 7.6.1810 release time.

Other people (such as bstinson, arrfab and hughesjr) can probably help 
with creating and publishing an updated centos-release-* package, but 
the usual tagging procedure to extras will apply. The SIG Guide 
https://wiki.centos.org/SIGGuide should have all the needed details for 
this (if not, complain to bstinson). It is highly recommended to 
actually test your new centos-release-* package from buildlogs before 
you ask that package to be signed and pushed to extras.

The holiday season is fast approaching so (I) don't expect much activity 
regarding these changes in the following days. I'm hoping that the SIGs 
would take a look at this in early 2019, though. Thanks to those SIGs 
who have already made these changes to their centos-release-* packages!

If you have questions, feel free to ask either here or on #centos-devel. 
Thanks for your time!