Chapter 1. Frequently Asked Questions

Anyone who wishes to read and/or edit the Pacemaker source code. Casual contributors should feel free to read just this FAQ, and consult other sections as needed.

The source code for Pacemaker is kept on GitHub, as are all software projects under the ClusterLabs umbrella. Pacemaker uses Git for source code management. If you are a Git newbie, the gittutorial(7) man page is an excellent starting point. If you’re familiar with using Git from the command line, you can create a local copy of the Pacemaker source code with: git clone https://github.com/ClusterLabs/pacemaker.git pacemaker

See INSTALL.md in the main checkout directory.

You’ll be mostly fine if you simply follow the example of existing code. When unsure, see the relevant section of this document for language-specific recommendations. Pacemaker has grown and evolved organically over many years, so you will see much code that doesn’t conform to the current guidelines. We discourage making changes solely to bring code into conformance, as any change requires developer time for review and opens the possibility of adding bugs. However, new code should follow the guidelines, and it is fine to bring lines of older code into conformance when modifying that code for other reasons.

See existing examples in the git log. The first line should look like change-type: affected-code: explanation where change-type can be Fix or Bug for most bug fixes, Feature for new features, Log for changes to log messages or handling, Doc for changes to documentation or comments, or Test for changes in CTS and regression tests. You will sometimes see Low, Med (or Mid) and High used instead for bug fixes, to indicate the severity. The important thing is that only commits with Feature, Fix, Bug, or High will automatically be included in the change log for the next release. The affected-code is the name of the component(s) being changed, for example, crmd or libcrmcommon (it’s more free-form, so don’t sweat getting it exact). The explanation briefly describes the change. The git project recommends the entire summary line stay under 50 characters, but more is fine if needed for clarity. Except for the most simple and obvious of changes, the summary should be followed by a blank line and then a longer explanation of why the change was made.

Most importantly, Pacemaker has regression tests for most major components; these will automatically be run for any pull requests submitted through GitHub. Additionally, Pacemaker’s Cluster Test Suite (CTS) can be used to set up a test cluster and run a wide variety of complex tests. This document will have more detail on testing in the future.

Except where noted otherwise in the file itself, the source code for all Pacemaker programs is licensed under version 2 or later of the GNU General Public License (GPLv2+), its headers and libraries under version 2.1 or later of the less restrictive GNU Lesser General Public License (LGPLv2.1+), its documentation under version 4.0 or later of the Creative Commons Attribution-ShareAlike International Public License (CC-BY-SA), and its init scripts under the Revised BSD license. If you find any deviations from this policy, or wish to inquire about alternate licensing arrangements, please e-mail andrew@beekhof.net. Licensing issues are also discussed on the ClusterLabs wiki.

Contributions of bug fixes or new features are very much appreciated! Patches can be submitted as pull requests via GitHub (the preferred method, due to its excellent features), or e-mailed to the developers@clusterlabs.org mailing list as an attachment in a format Git can import.

Ask on the developers@clusterlabs.org mailing list for development-related questions, or on the users@clusterlabs.org mailing list for general questions about using Pacemaker. Developers often also hang out on freenode’s #clusterlabs IRC channel.