How to Setup Jenkins Pipeline Environment Variables. Jenkins is an open-source automation server. It helps automate the parts of software development related to building, testing, and deploying, facilitating continuous integration and continuous delivery. It is a server-based system that runs in servlet containers such as Apache Tomcat. In addition, it supports version control tools, including AccuRev, CVS, Subversion, Git, Mercurial, Perforce, ClearCase, and RTC. It can execute Apache Ant, Apache Maven, and sbt based projects and arbitrary shell scripts, and Windows batch commands.