Currently the default yum configuration references mirror.centos.org.
When yum looks up the IP address it finds several but it will only try
one and fail if that server is down or does not have the headers for
whatever reason.
If yum were to reference a mirrorlist it would skip servers that fail
and keep trying them all until it finds one that works or exhausts all
the mirrors. Centos would host a file on their web server for each
repository that has a list of mirror baseurls.
I created a test script to generate mirrorlists from the
mirror.centos.org DNS lookup and changed yum to reference the local
files that were generated as a mirrorlist= and it worked. The
non-synced servers that did not have the correct directories setup were
skipped and it found servers that did work.
Are there any plans to provide a centos-yumconf rpm that links to a
mirrorlist on centos.org instead of just using the DNS round-robin of
mirror.centos.org which will cause yum to fail if it happens to get an
IP that does not work? Centos would just need to change the mirrorlist
file on the main website to change mirrors for clients. Each mirror
would need to have a DNS entry of its own but it would make things work
better for updates when 1 server is not synced properly or has some
other problem(down, etc).
---- begin gen-centos-mirrorlist.sh script ----
#!/bin/sh
host mirror.centos.org | grep " has address " | cut -f 4 -d " " | \
sed "s#.*#http://\0/centos/4/updates/i386/#"; > \
/etc/centos-mirror-updates.list
host mirror.centos.org | grep " has address " | cut -f 4 -d " " | \
sed "s#.*#http://\0/centos/4/os/i386/#"; > /etc/centos-mirror-base.list
host mirror.centos.org | grep " has address " | cut -f 4 -d " " | \
sed "s#.*#http://\0/centos/4/addons/i386/#"; > \
/etc/centos-mirror-addons.list
host mirror.centos.org | grep " has address " | cut -f 4 -d " " | \
sed "s#.*#http://\0/centos/4/extras/i386/#"; > \
/etc/centos-mirror-extras.list
host mirror.centos.org | grep " has address " | cut -f 4 -d " " | \
sed "s#.*#http://\0/centos/4/centosplus/i386/#"; > \
/etc/centos-mirror-centosplus.list
---- end generation script ----
---- begin changed CentOS-Base.repo yum configuration ----
[base]
name=CentOS-$releasever - Base
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
mirrorlist=file:///etc/centos-mirror-base.list
gpgcheck=1
#released updates
[update]
name=CentOS-$releasever - Updates
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
mirrorlist=file:///etc/centos-mirror-updates.list
gpgcheck=1
#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever - Addons
#baseurl=http://mirror.centos.org/centos/$releasever/addons/$basearch/
mirrorlist=file:///etc/centos-mirror-addons.list
gpgcheck=1
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
mirrorlist=file:///etc/centos-mirror-extras.list
gpgcheck=1
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
mirrorlist=file:///etc/centos-mirror-centosplus.list
gpgcheck=1
enabled=0
NOTE: My hack with using IPs from mirror.centos.org has the flaw in that
the http servers in the list files are referenced by IP. If the mirror
http server is using a Name Virtual Host and centos is not the default
web site for that IP then it might try pulling the files from the wrong
configured virtual host on that mirror. This might make some mirrors
not work.
