Integrating Trac, Jenkins and Cobbler—Customizing Linux Operating Systems for Organizational Needs

Organizations supporting Linux operating systems commonly have a need to build customized software to add or replace packages on production systems. This need comes from timing and policy differences between customers and the upstream distribution maintainers. In practice, bugs and security concerns reported by customers will be prioritized to appropriate levels for the distribution maintainers who are trying to support all their customers. This means that customers often need to support patches to fill the gap, especially for unique needs, until distribution maintainers resolve the bugs. </EndSoapBox>

Customers who desire to fill the support gap internally should choose tools that the distribution maintainers use to build packages whenever possible. However, third-party software packages often present challenges to integrate them into the distribution properly. Often these packages do not follow packaging guidelines and, as a result, do not support all distribution configurations or procedures for administration. These packages often require more generic processes to resolve the improper packaging. </EndSoapBoxAgain>

From this point on, the tools and methods discussed in this article are specific to Red Hat Enterprise Linux (RHEL). These tools and methods also work with derivative distributions like Scientific Linux or Community Enterprise OS (CentOS). Some of the tools do include support for distributions based on Debian. However, specifics on implementation of the process focus on integration with RHEL-based systems.

The build phase of the process (described in "A Process for Managing and Customizing HPC Operating Systems" in the April 2014 issue of LJ) requires three pieces of software that can be filled by Trac, Cobbler and Jenkins. However, these pieces of software do not fill all the gaps present from downloading source code to creation of the overlay repository. Further tools and processes are gained by analysis of the upstream distribution's package management process and guidelines.

The application of the Fedora Packaging Guidelines and its counterpart EPEL Packaging Guidelines are good references for how to package software for RHEL-based systems appropriately. These guidelines call out specifics that often are overlooked by first-time packagers. Also, tools used in the process, such as Mock, work well with the software mentioned previously.

Fedora uses other tools to manage building packages and repositories. These tools are very specific to Fedora packaging needs and are not general enough for use in our organization. This is primarily due to technical reasons and features that I go into in the Jenkins section of the article.

The rest of this article focuses on implementing Trac, Cobbler, Jenkins, and the gaps between the three systems. Some of the gaps are filled using native plugins associated with the three systems. However, others are left to be implemented using scripts and processes requiring human interactions. There are points where human interaction is required to facilitate communication between groups, and other points are where the process is missing a well implemented piece of software. I discuss setup, configuration and integration of Trac, Cobbler and Jenkins, along with some requests for community support.

Trac

Trac consists of an issue-tracking system and wiki environment to support software development projects. However, Trac also works well for supporting the maintenance of administrative processes and managing change on production systems. I'm going to discuss the mapping to apply a software development process to the process by which one administers a production system.

I realize that talking about issue tracking and wiki software is a religious topic for some. Everyone has their favorite software, and these two kinds of systems have more than enough open-source options out there from which people can choose. I want to focus on the features that we have found useful at EMSL to support our HPC system and how we use them.

The ticket-tracking system works well for managing small changes on production systems. These small changes may include individual critical updates, configuration changes and requests from users. The purpose of these tickets is to record relevant technical information about the changes for administrators as well as management. This helps all stakeholders understand the cost and priority of the change. These small changes can be aggregated into milestones, which correspond to outage dates. This provides a starting framework to track what change happens and when on production systems.

Trac's wiki has features that are required for the process. The first is the ability to maintain a history of changes to individual pages. This is ideal for storing documents and procedures. Another feature is the ability to reference milestones from within pages. This feature is extremely useful, since by entering a single line in the wiki, it displays all tickets associated with the milestone in one simple line. These two features help maintain the procedures and outage pages in the wiki.

The administrative procedures are documented in the wiki, and they include but are not limited to software configuration, startup, shutdown and re-install. The time required to perform these administrative procedures also should be noted in the page. We also make sure to use the plain-text options for specifying commands that need to be run, as other fonts may confuse readers. In many cases, we have specified the specific command to run in these procedures. For complex systems, creating multiple pages for a particular procedure is prudent. However, cross links between pages should be added to note when one part of the procedure from each page should be followed.

Trac's plugin infrastructure does not have plugins to Jenkins or Cobbler. However, what would be the point of a plugin going from Trac to continuous integration or provisioning? Most software development models keep ticket systems limited to human interaction between the issuer of the ticket and the people resolving it. Some exceptions are when tickets are considered resolved but are waiting for integration testing. Automated tests could be triggered by the ticketing system when the ticket's state is changed. However, mapping these sorts of features to administrative procedures for managing production systems do not apply.

Cobbler

Cobbler works well for synchronizing RPM-based repositories and using those repositories to deploy systems. The RPMs are synchronized daily from Jenkins and distribution maintainers. The other important feature is to exclude certain packages from being synchronized locally. These features provide a platform to deploy systems that have specific customized packages for use in the enterprise.

The initial setup for Cobbler is to copy the primary repositories for the distribution of your choice to "repos" in Cobbler. The included repositories from Scientific Linux are the base operating system, fastbugs and security. Other distributions have similar repository configurations (see the Repositories and Locations sidebar). The other repository to include is EPEL, as it contains Mock and other tools used to build RPMs. There are other repositories that individual organizations should look into, although these four repositories are all that is needed.

Repositories and Locations

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David Brown is a high-performance computing system administrator with a B.S. in Computer Science from Washington State University.