Scripting YUM provides search using Python

Update 24-06-15

Thanks to this page, I fixed my script. It no longer requires root privillages. I also muted informational messages because they were not very informational.

The Story

Today I had a list of files (nagios check scripts), and I wanted to check for every file if there’s a package containing it (I’m a big fan of getting files from the repo rather than downloading manually). Although YUM provides a way to search for packages containing a file pattern, like this:

yum provides '*/check_mailq'

The output is quite complicated to parse:

Loaded plugins: fastestmirror, presto
Loading mirror speeds from cached hostfile
 * base: mirrors.seas.harvard.edu
 * epel: mirror.symnds.com
 * extras: mirror.ash.fastserv.com
 * updates: mirror.cogentco.com
private-chef-1.4.15-1.el6.x86_64 : The full stack of private-chef
Repo        : chef-stable
Matched from:
Filename    : /opt/opscode/embedded/nagios/libexec/check_mailq



private-chef-1.4.14-1.el6.x86_64 : The full stack of private-chef
Repo        : chef-stable
Matched from:
Filename    : /opt/opscode/embedded/nagios/libexec/check_mailq



nagios-plugins-mailq-1.4.16-10.el6.x86_64 : Nagios Plugin - check_mailq
Repo        : epel
Matched from:
Filename    : /usr/lib64/nagios/plugins/check_mailq

The first part is irrelevant (info messages that should IMO go to stderr), and every entry in the actual result contains multiple lines… bah. Luckily, YUM is completely written in python so we can copy its behaviour with a custom script.

The Solution

I used this post to help me with basic discovery. The rest is my work.
This script requires root (or sudo). I didn’t bother finding out how to run it otherwise.

import logging
import yum
yb=yum.YumBase()
yb.setCacheDir()
logging.disable(logging.WARNING) # Mute loggers
files=['YOUR','file','name','go','here']

res={}
for f in files:
  r=yb.searchPackageProvides(['*/'+f]) # ,('*/'+f+'.*')
  res[f]=map(lambda x: x.name, r)

The following part varies by your objective. I wanted to list the packages required for each file, and also a sorted list of all relevant packages:

print '**No matches:'
for p in filter(lambda x: len(res[x])==0, res): print p

print
print '**Matches:'
for p in filter(lambda x: len(res[x])>0, res): print p,res[p]

print
print '**Duplicates:'
for p in filter(lambda x: len(res[x])>1, res): print p,res[p]

print
print '**Packages to be installed:'
pkgs=map(lambda x: res[x],filter(lambda x: len(res[x])>0, res))
print sorted(list(set([item for sublist in pkgs for item in sublist])))

The result is quite nice:

**No matches:
check_sockets.sh
check_threads.sh
check_exit_code.pl
check_duplicate_process

**Matches:
check_nagios ['nagios-plugins-nagios']
check_breeze ['nagios-plugins-breeze']
check_mrtgtraf ['nagios-plugins-mrtgtraf']
check_ldap ['check-mk', 'check-mk-docs', 'nagios-plugins-ldap']
check_ircd ['nagios-plugins-ircd']

**Duplicates:
check_ldap ['check-mk', 'check-mk-docs', 'nagios-plugins-ldap']
check_dns ['nagios-plugins-dns', 'check-mk', 'check-mk-docs']
check_smtp ['check-mk', 'nagios-plugins-smtp', 'check-mk-docs']

**Packages to be installed:
['check-mk', 'check-mk-docs', 'nagios-plugins-breeze', 'nagios-plugins-dns', 'nagios-plugins-ircd', 'nagios-plugins-ldap', 'nagios-plugins-mrtgtraf', 'nagios-plugins-nagios', 'nagios-plugins-smtp']

Looks good.