Yum metadata file does not match checksum error and fix

While using yum/ CentOS5.4 at a client site, came across error on trying to search for a package.  The error indicated a checksum mismatch like:

Loaded plugins: fastestmirror

openx-artifactory-released/primary                                                  | 1.1 MB     00:00     

http://abcd.company.org:8081/artifactory/libs-release-local/repodata/primary.xml.gz: [Errno -1] Metadata file does not match checksum

Trying other mirror.

Error: failure: repodata/primary.xml.gz from openx-artifactory-released: [Errno 256] No more mirrors to try.

This happens when the repo metadata files are out of sync for some reason (including outdated cache) and one of the quick way to resolve is to force not checking the checksum with fastestmirror of yum which can take command line option of user confirmation input (y(es) or N(o)).  So ran

> sudo yum -y remove yum-fastestmirror

If one doesn't check the dependency before removing a package one can get bitten. And that is what I ended up with :(.

Before running the above command I should have checked with 

> yum deplist yum-fastestmirror

Excluding Packages from CentOS-5 - Plus

Finished

Finding dependencies: 

package: yum-fastestmirror.noarch 1.1.16-14.el5.centos.1

  dependency: config(yum-fastestmirror) = 1.1.16-14.el5.centos.1

   provider: yum-fastestmirror.noarch 1.1.16-14.el5.centos.1

  dependency: yum >= 3.0

   provider: yum.noarch 3.2.22-20.el5.centos

   provider: yum.noarch 3.2.22-20.el5.centos

package: yum-fastestmirror.noarch 1.1.16-13.el5.centos

  dependency: config(yum-fastestmirror) = 1.1.16-13.el5.centos

   provider: yum-fastestmirror.noarch 1.1.16-13.el5.centos

   provider: yum-fastestmirror.noarch 1.1.16-13.el5.centos

  dependency: yum >= 3.0

   provider: yum.noarch 3.2.22-20.el5.centos

   provider: yum.noarch 3.2.22-20.el5.centos

and also yum itself depends on yum-fastestmirror!

> yum deplist yum

...

  dependency: yum-fastestmirror

   provider: yum-fastestmirror.noarch 1.1.16-13.el5.centos

   provider: yum-fastestmirror.noarch 1.1.16-13.el5.centos

   provider: yum-fastestmirror.noarch 1.1.16-14.el5.centos.1

....

On removing yum-fastestmirror (to quickly avoid the metadata checksum error), I ended up with bigger problem of having uninstalled the yum itself!

> yum search python

-bash: yum: command not found

> rpm -qi yum

package yum is not installed

Now the only solution is to get the new package of yum for this CentOS and install new.  I couldn't perform wget or http from behind the firewall and proxy due to security network on this system.  

> cat /etc/redhat-release

OpenX release 5.4 (based on CentOS 5.4)

httped to http://vault.centos.org/5.4/os/i386/CentOS/ and download yum 3.2.22 (yum-3.2.22-20.el5.centos.noarch.rpm) and yum-fastestmirror & yum-utils to my local laptop.  Then scped the packages to dev system

On the dev box, then, I ran

> sudo rpm -ivh yum-3.2.22-20.el5.centos.noarch.rpm yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm 

Note: You need to provide the both rpms at the same time (in single command) due to fact there is cyclic dependency.  If you try installing one at a time each will complain that other package is missing!

Once that install was good, I could perform

> yum search ctags