What is Jenkins?
Jenkins is an open-source continuous integration/continuous delivery and deployment (CI/CD) automation software DevOps tool written in the Java programming language. It is used to implement CI/CD workflows, called pipelines.
Pipelines automate testing and reporting on isolated changes in a larger code base in real time and facilitate the integration of disparate branches of the code into a main branch. They also rapidly detect defects in a code base, build the software, automate testing of their builds, prepare the code base for deployment (delivery), and ultimately deploy code to containers and virtual machines, as well as bare metal and cloud servers.
How does Jenkins work?
Jenkins runs as a server on a variety of platforms including Windows, MacOS, Unix variants and especially, Linux. It requires a Java 8 VM and above and can be run on the Oracle JRE or OpenJDK. Usually, Jenkins runs as a Java servlet within a Jetty application server. It can be run on other Java application servers such as Apache Tomcat. More recently, Jenkins has been adapted to run in a Docker container. There are read-only Jenkins images available in the Docker Hub online repository.
What are Plugins?
A plugin is an enhancement to the Jenkins system. They help extend Jenkins capabilities and integrated Jenkins with other software. Plugins can be downloaded from the online Jenkins Plugin repository and loaded using the Jenkins Web UI or CLI. Currently, the Jenkins community claims over 1500 plugins available for a wide range of uses.
Jenkins Security:
Jenkins security revolves around securing the server and the user. Server security is achieved in the same way any other server is secured. Access to where it resides, such as a VM or bare metal server, is configured to allow for the fewest number of processes to communicate with the server. This is accomplished through typical server OS and networking security features.