I’ve been involved in setting up continuous integration for quite a while. So far so good. However, because the project is composed of several components, things were getting a little ugly. The problem was that it spent far too long to finish a complete build, which made me split it into two separate ones. One for the normal, relatively fast build which only performs unit tests and limited report generating. The other one is daily build which takes much longer to generate a complete Maven project site. I still wasn’t very satisfied with this strategy because the normal build still took me 10 minutes to complete. It did not provide static analysis report either (which I really think should be part of a normal build).
The tools I use are CruiseControl and Maven. I have set up one CruiseControl instance for each of the two builds. The root cause of the slowness is that there are many components. Each time we build, we build every component, from the first to the last. Even if only one of the components have changes, we still build all of them every time. I have thought of having one CruiseControl instance for each component. However, that did not work because I had no way of detecting binary dependency. Say if component A depends on component B, we should rebuild A when A has any change. We should also rebuild A as long as B has any change. If A and B all have their own separate CruiseControl instances, I don’t know how to achieve that effect.
Well, luckily I have spotted this paper today: Enterprise Continuous Integration Using Binary Dependencies. The basic idea is that we will publish the latest build artifacts of all components to a central repository. If component A depends on B, then it will fetch B from the repository instead of building B manually. When we are building A, we check in the repository whether the latest version of B has been modified or not. That way we can detect changes from binary dependencies!
The key for me is that CruiseControl can have multiple modification sets. So I will have one modification set for source code repository and one for binary dependencies. By using Maven, I already have the ability to detect changes of dependenciy versions. Luckily CruiseControl even has a modification set called mavensnapshotdependency (finally there’s some return from using Maven). This way I don’t have to rebuild all components every time. Only build necessary components when only necessarily. What a perfect world!
