One thing that is clear in IT is that the market moves very fast, and every few years, a new trend breaks what was considered the perfect solution for a problem. CI software is not an exception to this. In the last few years (taking into account that this book was written in 2017), Infrastructure as Code has drawn a lot of attention to the DevOps world, but in CI, its equivalent is Pipelines as Code.
Jenkins and Bamboo have added support for declarative pipelines recently, but they are not built around them.
Drone is probably the newest CI server in the market. I decided to introduce it in this chapter as it was a big revelation to me when I found out about it working in nearForm Ltd. By that time, I was well used to Jenkins and it suited every single use case that I could come across in my professional life, from CI to continuous delivery and sometimes even as a bastion host using a feature called callback URL, where a job could be triggered by sending an HTTP request...