Dependency resolution issues

Bug #453543 reported by BJ Dierkes on 2009-10-16
This bug affects 1 person
Affects Status Importance Assigned to Milestone
IUS Community Project
BJ Dierkes

Bug Description

[root@centos5-2 ~]# rpm -qa | grep php

[root@centos5-2 ~]# yum repolist
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
 * epel:
 * base:
 * updates:
 * addons:
 * ius:
 * extras:
epel | 3.4 kB 00:00
base | 1.1 kB 00:00
updates | 951 B 00:00
addons | 951 B 00:00
ius | 1.9 kB 00:00
primary.sqlite.bz2 | 105 kB 00:00
extras | 1.1 kB 00:00
repo id repo name status
addons CentOS-5 - Addons enabled : 0
base CentOS-5 - Base enabled : 3272
epel Extra Packages for Enterprise Linux 5 - enabled : 4469
extras CentOS-5 - Extras enabled : 288
ius IUS Community Packages for Enterprise Li enabled : 187
updates CentOS-5 - Updates enabled : 700
repolist: 8916

[root@centos5-2 ~]# yum install cacti
...output snipped...
Resolving Dependencies
--> Running transaction check
---> Package cacti.noarch 0:0.8.7e-1.el5 set to be updated
--> Processing Dependency: php-mysql for package: cacti
--> Processing Dependency: php-snmp for package: cacti
--> Running transaction check
---> Package php-mysql.x86_64 0:5.1.6-23.el5 set to be updated
--> Processing Dependency: php-common = 5.1.6-23.el5 for package: php-mysql
--> Processing Dependency: php-pdo for package: php-mysql
---> Package php-snmp.x86_64 0:5.1.6-23.el5 set to be updated
--> Running transaction check
---> Package php-common.x86_64 0:5.1.6-23.el5 set to be updated
---> Package php-pdo.x86_64 0:5.1.6-23.el5 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

 Package Arch Version Repository Size
 cacti noarch 0.8.7e-1.el5 epel 2.1 M
Installing for dependencies:
 php-common x86_64 5.1.6-23.el5 base 154 k
 php-mysql x86_64 5.1.6-23.el5 base 87 k
 php-pdo x86_64 5.1.6-23.el5 base 64 k
 php-snmp x86_64 5.1.6-23.el5 base 29 k

Transaction Summary
Install 5 Package(s)
Update 0 Package(s)
Remove 0 Package(s)

Total download size: 2.5 M
Is this ok [y/N]:

Related branches

BJ Dierkes (derks) wrote :

The following is the Yum feature request added upstream

An issue exists with compare_providers if the packages that provide a dependency do not have the same name. For example:

root@el5-x86_64 ~]# rpm -qa | grep php

root@el5-x86_64 ~]# yum install cacti

In this situation, the following is true based on the repos available:

    * cacti requires php-mysql, php-snmp
    * php53-mysql provides php-mysql, php53-snmp provides php-snmp
    * php-mysql provides php-mysql, php-snmp provides php-snmp (stock rhel packages)

That said, Yum resolves the dependency with stock php-mysql, and php-snmp even though php53 is installed and php53-mysql/php53-snmp are available. This happens because compare_providers does not compare versions if the package name is different, and php-mysql/php-snmp are the shortest package names so they win out.

I propose an additional check to add to compare providers to accommodate the comparison of different package names that provide the same dependency, based on whether that provider's sourcerpm is already installed. Meaning, if the providers source rpm is already installed and provides the dependency then it should be awarded points.

This might sound expensive, but the only expensive part is generating the self.installedSourceRPMS list (which is only once). The per pkg operation is simply a 'if po.sourcerpm in self.installedSourceRPMS' check.

Patch against latest git checkout attached.

BJ Dierkes (derks) wrote :

Temporary work around: Add items to the global exclude list. For example, when using the php52 packages, add 'exclude=php*5.1*' to /etc/yum.conf. Not a great solution, but temporary.

BJ Dierkes (derks) wrote :

Packages for yum3 have been added to ius-el5-testing and should be pushed to stable within the next week after some more testing. Fingers crossed this issue will be fixed in the next Yum release as well as RHEL 5.5 (we hope). Once that happens we will drop the optional yum3 package.

Quick instructs:

yumdownloader yum3
rpm -e yum --nodeps
rpm -Uvh yum3*.rpm

It is exactly the same version as RHEL5 with 1 additional patch to add better dependency resolution (which is being added upstream).

BJ Dierkes (derks) wrote :

This should be resolved once yum-3.2.22-23.el5 makes it to RHEL5.

BJ Dierkes (derks) wrote :

This is now resolved in RHEL 5.5/RHEL 6 .... therefore, the yum3.ius package is no longer required.

Changed in ius:
status: Confirmed → Fix Released
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