Archive for May, 2010

IUS Community RPMs for Red Hats RHEL

Sunday, May 16th, 2010

I was criticizing that software in RHEL is too outdated for web servers quite soon after release, see my blog post While this is true for a system fully supported by Red Hat, I learned an alternative from a comment on the post. This alternative is the so called IUS community repository.

About the IUS Community Project
The project was launched in September 2009. In spite of being a young project, it has a history. At Rackspace, a large hosting company which is operating thousands of production (web) servers, it was an internal project since 2006. They decided to build up a community around it, like Fedora is for RHEL, Quote: “IUS is The Fedora of Rackspace RPMS”

Like for other community repositories out there, you cannot expect a “official” support neither from Red Hat nor from IUS or Rackspace. Of course there are the usual support sources for communities such as forums, IRC, bugtracker etc.

The difference to other repositories
While most community repositories such as EPEL, rpmforge etc. are focused on providing missing software, IUS focuses on providing upgrades for web server related software which is included in RHEL. This includes PHP, Python, MySQL and others.

Package conflicts with the stock distribution
One may think replace stock software with newer version is tricky and create conflicts. There is one way to find out: Lets give it a try…

The test
The server is a basic install of the yesterday released Centos 5.5. The following installation turns this machine in a lightweight LAMP server:

yum install httpd php-mysql php php-cli php-common php-pgsql php-dba php-pdo php-gd mysql-server perl-DBD-MySQL.

Now we have the situation like it exists in many companies: An outdated webserver. Now we want to upgrade PHP to 5.3.x. Lets see what happens.

[root@centos5 ~]# rpm -i
warning: /var/tmp/rpm-xfer.o6JH6k: Header V3 DSA signature: NOKEY, key ID 9cd4953f
[root@centos5 ~]# rpm -i
warning: /var/tmp/rpm-xfer.MRnuo8: Header V3 DSA signature: NOKEY, key ID 9cd4953f
package epel-release-5-3.noarch (which is newer than epel-release-1-1.ius.el5.noarch) is already installed
[root@centos5 ~]#

Hmm… no GPG key…
The second output is confusing me. Is the package just a clone of epel-release-5-3.noarch? Lets go forward to see if it is working.

“yum clean-all && yum check-update” did not show any pending updates, so far so good. Now lets try to upgrade php.

root@centos5 ~]# yum install php53
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons:
* base:
* epel:
* extras:
* ius:
* updates:
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package php53.x86_64 0:5.3.2-3.ius.el5 set to be updated
--> Processing Dependency: php53-common = 5.3.2-3.ius.el5 for package: php53
--> Processing Dependency: php53-cli = 5.3.2-3.ius.el5 for package: php53
--> Processing Dependency: php53-pear >= 1:1.8 for package: php53

[omitted output]

--> Processing Conflict: php53 conflicts php < 5.3 --> Finished Dependency Resolution
php53-5.3.2-3.ius.el5.x86_64 from ius has depsolving problems
--> php53 conflicts with php
Error: php53 conflicts with php
You could try using --skip-broken to work around the problem
You could try running: package-cleanup --problems
package-cleanup --dupes
rpm -Va --nofiles --nodigest
The program package-cleanup is found in the yum-utils package.

Correct behaviour, since it is a replacement package. After removing php (and only php) yum was complaining about more conflicts. After removing all php related packages installed to prepare for the test, needed to be removed. So the dependencies has been proper solved. Also the installation of related stock distribution packages such as “php-pgsql” has been successfully prevented.

The IUS community repositories are working as expected. With such a basic test I cannot promise if there are not hidden conflicts with packages between stock RHEL/CentOS packages and those from IUS. The experience on the long term will bring more clarity. I think is is sane to do some real-life tests with servers that are in an early project phase.

Further readings:

Have fun!

CentOS 5.5 released

Sunday, May 16th, 2010

On May 15, the CentOS project released version 5.5 of its enterprise Linux. It is based on the sources of RHEL5.5 which was released on March, 31.

Unfortunately they – like always – removed the rhn-client-tools and friends from upstream. This is a pity, since it takes more efforts to manage CentOS-installation in Spacewalk.

For the full release notes have a look at

Have fun!

KVM supports live migration between CPUs with different features

Saturday, May 15th, 2010

The video is a bit old, it is from November 2008. But it is still quite interesting to see and discuss about it. With KVM you can upgrade your farm of servers easy, it does not matter if the new servers have CPUs with new features or not. I’m not sure if you can do this with ESX, I guess not, you probably need to migrate them shut down.

Have fun!

An example why open source software is cool

Saturday, May 15th, 2010

Recently I have set up an Apache Tomcat. As a replacement for the Tomcat manager I deployed Psi-Probe for easy deployment and access to statistics.

Afterwards I installed the production software which needs to add a JVM parameter to have the proper date and time format used in Switzerland. This had a unwanted side-effect to Psi-Probe. The Interface switched to German, no way to switch the language back to English. Since my mother tongue is German, no big deal so far. Really? No! I had really problems to understand what navigation items etc.  are meaning. The German translation was that bad, it actually crippled the application.

I had the choice to either life with it, or change it and contribute it to the project. I made the later. It was about one hour of work. Hours after submitting, the changed translation file it was in SVN. The next version now comes with a much improved German translation.

This is how open source software works. If someone is not happy with the product, simply change the annoying things and submit it upstream. By the way: Psi-Probe itself is a fork of Lambda-Probe which was not maintained anymore from its origin project owner.

Try to do that with closed source software…

Have fun!

RHN Inter-Satellite-Sync is kind of tricky and picky

Wednesday, May 5th, 2010

If you try to establish an ISS (Inter Satellite Sync) between two RHN Satellites, do not fully trust the documentation. A slave Satellite must be named by a hostname (IP is not enough) and must have an A and a PTR DNS record or have an /etc/hosts entry. Check it before restarting the satellite by issuing rhn-satellite restart. The check is simply done by entering gethostip and getent hosts <IP-address> on the commandline.

When Quoting the documentaion at Red Hats web site: means: A hostname, not just an IP. It is not clearly stated what kind of quality such an entry needs to have.


Have fun!