[Yum] dag repo problems

[Michael Stenner]

On Fri, Aug 04, 2006 at 04:44:23PM +0000, peter wrote:
> > try gethostip rather than nslookup.  I've seen issues with
> > /etc/nsswitch.conf and (for example) nis cause calls to
> > gethostbyname(3) to fail.
> 
> I think this is the reverse of the problem. What I want is for *yum*
> (or rather, Python) to do the lookup reliably. If I manually lookup
> the hostname for a repo, I get the correct IP addresses from nslookup
> (demonstrable by the fact that I can then manually go to the repo
> URI and see the files). But yum tells me that the repo is not there
> or is inaccessible, which is patently untrue.

I'm not helping you solve your problem (yet).  I'm helping you
diagnose it.  nislookup and python (urlgrabber/urllib2/socket) use
different methods for DNS lookups.  Python calls gethostbyname under
the hood, which talks to the OS and does a bunch of clever things like
/etc/hosts, local database lookups, nis, etc.  nslookup does something
different.  I think it goes to dns directly (I'm not sure, though).
Anyway, I've seen cases where nslookup works but gethostip does not.
In those cases, calls to gethostbyname from python fail.

So, I suggest you try gethostip rather than nslookup and see if it
fails.  If it does, then I suggest looking in the direction of
/etc/nsswitch.conf.

> My guess is that there is a timing problem somewhere: something is
> either expiring or simply failing to look something up. 
> 
> I'll look at the code and see if I can set some tracing breakpoints
> which will show me what yum is actually trying to do. Currently it
> just spins its wheels and says there are no more mirrors to try,
> without having specified what it found wrong with the ones it tried.
> I'm simply unwilling to believe that it couldn't turn up a working 
> mirror for updates-released :-)

I'm suggesting a 2-second check.  Do it first before you dive into yum
code.  Then tell me what you find and we'll go from there.

					-Michael
-- 
  Michael D. Stenner                            mstenner at ece.arizona.edu
  ECE Department and Optical Sciences Center                520-626-1619
  University of Arizona                                         ECE 524G