Going beyond Builds with Build Servers

A build server provides great benefits to a development team, including:

* Convenient way of sharing build results and artifacts.
* Ability to run builds without having to mess with command line parameters.
* Tight integration with version control.
* History and statistics.
* Accountability and audit (e.g., who ran what build).

In most instances build servers, such as Hudson, Continuum or LuntBuild are used mostly for continuous integration and development builds. But they can be used for much more than that. A build server provides a generic framework for performing any kind of deployment or operations-related activity, including deployment of an application into acceptance and production environments, configuring of an app server (e.g., setting up data sources and JMS destinations) and even app server monitoring.

Several things make it possible. Build servers have flexible scheduling capabilities allowing to schedule any kind of repetitive activity, such as “pinging” a server every 15 minutes. Integration with version control makes it easier to manage the scripts. Very often, scripts for administration or configuration tasks are created in an ad-hoc fashion with multiple versions scattered around different servers and directories. A build server is able to check out a specific version of a script from a version control system and execute it. In other words, a build server helps treating admin scripts same way with business applications. Additionally, build servers can publish logs. This is powerful, since it lets anyone (who has permissions) see results of configuration activities or monitoring scripts. Finally, build servers do a great job of notifying all interested parties via e-mail, RSS, IM and other means of communication.

Security could be another important benefit of leveraging a build server outside of development builds. Usually, access to production environments is tightly controlled. In many organizations, developers have no access to production whatsoever. Build server can help enforce this policy yet give developers visibility into the details of production deployment. This can be done by creating a separate build configuration just for production deployments.

All the benefits that I mentioned in the beginning of this post also apply to non-build activities. For example, the ability to see history of all production deployments can be very valuable.

Not all build servers are created equal, especially open source ones. Security, for one, could be supported and implemented very differently in different products. Support for various version control features, such as labels and branches, also varies. In other words, careful evaluation is required before embarking on an effort of expanding the build server beyond development. But more importantly, this effort requires buy-in from operations and support organization and other groups that will become users of the build server.

As an example, with one of our clients we’ve been able to implement a number of interesting non-build functions using a build server (we started with LuntBuild and now migrated to Hudson):

* Deployment of pre-built EAR/WAR files into test and production environments.
* Configuration of application servers. In our case, most of the app server resources are shared, so we run the configuration script separately from application deployments. In fact, we treat configuration as a separate “unit of release” with its own lifecycle.
* Monitoring of application servers. We have a script which tests health of application servers using JMX.
* Log scanning. We’ve implemented a custom log scanning tool which “greps” logs for various patterns. The build server sends notification if a pattern is found in the logs.

Many of these functions can be accomplished using various commercial system management and monitoring products. These products however can get expensive and very often organizations simply don’t have enough licenses to cover all environments. So a combination of custom scripts with a build server provides a viable alternative.