When designing Continuous Delivery pipelines, the question remains, which technology to use. This includes not only the CI server itself, but all the tools used within the development workflow such as version control, artifact repositories, build systems, and runtime technologies.

What technology is being used depends on the actual requirements and not least of what the team is familiar with. The following examples will make use of Jenkins, Git, Maven, Docker, and Kubernetes. As of writing this book these are widely-used technologies. However, for engineers it's more important to comprehend the underlying principles and motivations. The technology is quite interchangeable.

No matter what tools are selected, it's advisable to use the tools for what they are meant for. Experience shows that tools are quite often being misused for tasks that would better be executed using different technology. A prime example for this is the build system, for example Maven. Projects often define build processes that have more responsibilities than just building the artifacts.

It makes sense not to mix responsibilities of building containers or deploying software into the artifact build. These concerns are preferably realized directly by the Continuous Integration server. Bringing these steps into the build process unnecessarily couples the build technology to the environment.

It's therefore advisable to use the tools for what they were intended to do, in a straightforward way. For example, Docker containers are advisably built via the corresponding Docker binaries rather than build system plugins. Required abstraction layers are rather added in pipeline as code definitions, as demonstrated in the following examples.