Re: Default to fetching from CDN first?

[Greg Troxel <gdt%lexort.com@localhost>]

I agree with tls@ that we should optimize for use and package-checking
separately.

Right now, if the distfile isn't found on the original master site, we
just fetch from CDN.  I think tls@ is only talking about changing the
order.

We do need to be careful not to break the path of how distfiles get
mirrored and uploaded to MASTER_SITE_BACKUP.  But, I think if there
isn't a file matching the distinfo, failover will get to the original
MASTER_SITE.

As I see it, the only real downsides are

  for developers, having to endure N quick fails to get a new distfile
  after updating version numbers

  for everyone, having N quick fails before fetching a NO_SRC_ON_FTP
  package.

I think it would be good to figure out how to make the cdn used first,
without using MASTER_SITE_OVERRIDE, and a default-on variable to turn
that off.  But putting MASTER_SITE_OVERRIDE?= might actually be ok, with
people setting it to empty if that's what they want.

Can someone articulate possible problems from such a change, in terms of
a specific example of distfile versions that are or aren't in specific
places?

I do see the point that people would be less likely to notice a missing
upstream.   But once you have fetched the distfile, you won't either.


We are close to freeze, and this seems like a change that could have
unanticipated consequences, so I sort it into "after the branch".