Solving RPM installation conflicts

Peter Zaitsev

Feb. 25, 13 · Interview

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This post comes from Ignacio Nin at the MySQL Performance Blog.

Lately we’ve had many reports of the RPM packages for CentOS 5 (mostly) and CentOS 6 having issues when installing different combinations of our products, particularly with Percona Toolkit. Examples of bugs related to these issues are lp:1031427 and lp:1051874.

These problems arise when trying to install a package from the distribution that is linked against the version of libmysqlclient.so shipped by the distribution (libmysqlclient.so.15 for CentOS 5/libmysqlclient.so.16 for CentOS 6) and a version of Percona Server that depends on another version of libmysqlclient.so, usually more recent. Bug lp:1031427 is an example of this, and shows how the packages would conflict when trying to install libmysqlclient.so.

For example, when installing php-mysql alongside PS 5.5 in CentOS 6:

# yum -q install Percona-Server-server-55 php-mysql

Installing:
Percona-Server-server-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 15 M
php-mysql x86_64 5.3.3-14.el6_3 updates 79 k
Installing for dependencies:
Percona-Server-client-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 7.0 M
Percona-Server-shared-51 x86_64 5.1.67-rel14.3.506.rhel6 percona 2.8 M
Percona-Server-shared-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 787 k

Transaction Summary
=====================================================================================================================================================
Install 5 Package(s)

Is this ok [y/N]: y

Transaction Check Error:
file /usr/lib64/libmysqlclient.so conflicts between attempted installs of Percona-Server-shared-51-5.1.67-rel14.3.506.rhel6.x86_64 and Percona-Server-shared-55-5.5.29-rel29.4.401.rhel6.x86_64
file /usr/lib64/libmysqlclient_r.so conflicts between attempted installs of Percona-Server-shared-51-5.1.67-rel14.3.506.rhel6.x86_64 and Percona-Server-shared-55-5.5.29-rel29.4.401.rhel6.x86_64

The traditional solution for this situation was to provide a special package, Percona-Server-shared-compat (modeled after upstream’s MySQL-shared-compat) which would contain ALL versions of libmysqlclient.so.* together and wouldn’t conflict. Probably some of you are familiar with this approach.

 # yum -q install Percona-Server-server-55 Percona-Server-shared-compat php-mysql


Installing:

 Percona-Server-server-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 15 M

 Percona-Server-shared-compat x86_64 5.5.29-rel29.4.401.rhel6 percona 3.4 M

 php-mysql x86_64 5.3.3-14.el6_3 updates 79 k

 Installing for dependencies:

 Percona-Server-client-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 7.0 M

 Percona-Server-shared-55 x86_64 5.5.29-rel29.4.401.rhel6 percona 787 k

Transaction Summary
=====================================================================================================================================================
Install 5 Package(s)

Notice how PS-shared-compat installs along the -shared package, providing the older libmysqlclient.so.16 required by php-mysql.

However, this has proved non-intuitive and problematic, since the shared-compat package wouldn’t get selected unless explicitely installed — and many of our users would rather have it “just work” without requiring additional knowledge of what the particular workaround was, etc..

We’re now trying a solution in which our -shared packages won’t conflict anymore at libmysqlclient.so, so we are able to install them side-by-side, modelled after the mysql-libs packages provided by CentOS/Redhat. So even if the user wants to install PS 5.5 alongside packages that depend on 5.1/5.0, the -shared packages will work together. For example installing 5.5 and postfix in CentOS:

 # yum -q install Percona-Server-server-55 postfix

Installing:

 Percona-Server-server-55 x86_64 5.5.29-rel29.4.402.rhel5 percona-testing 19 M

 postfix x86_64 2:2.3.3-6.el5 base 3.8 M

 Installing for dependencies:

 Percona-SQL-shared-50 x86_64 5.0.92-b23.89.rhel5 percona-testing 1.8 M

 Percona-Server-client-55 x86_64 5.5.29-rel29.4.402.rhel5 percona-testing 9.1 M

 Percona-Server-shared-55 x86_64 5.5.29-rel29.4.402.rhel5 percona-testing 993 k

… and this will install without problems.

Additionally, this has the advantage of allowing an upgrade from 5.1 to 5.5 without uninstalling any software that depended on the old version.

# rpm -qa | grep ^Percona
Percona-Server-client-51-5.1.67-rel14.3.507.rhel6.x86_64
Percona-Server-shared-51-5.1.67-rel14.3.507.rhel6.x86_64
Percona-Server-server-51-5.1.67-rel14.3.507.rhel6.x86_64

In this case only Percona-Server-client-51 and Percona-Server-server-51 need be removed, allowing any package that depends on Percona-Server-shared-51 (providing libmysqlclient.so.16) to remain installed. After the server and client packages are uninstalled, you can install PS 5.5 without conflict.

The current package candidates for versions 5.0.92 (which required an update), 5.1.67-14.3 and 5.5.29-29.4 can be tested from the percona-testing repository. We encourage you to try these out and send us your feedback and/or file any bugs you find.

Installation instructions for Percona Testing repositories.

We’re aiming to include these fixes in our next releases of 5.1 and 5.5. Percona Toolkit users in particular will enjoy this update since it’ll mean no more trouble when installing it from repository!

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Published at DZone with permission of Peter Zaitsev, DZone MVB. See the original article here.

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