Jenkins

Jenkins
Name	Jenkins
Developer	Kohsuke Kawaguchi, CloudBees, Jenkins community
Released	02 February 2011
Programming language	Java
Operating system	Cross-platform
Genre	Continuous integration, Continuous delivery
License	MIT License

Jenkins. It is an open-source automation server written in Java that facilitates continuous integration and continuous delivery (CI/CD) in software development. Originally forked from the Hudson project after a dispute with Oracle Corporation, it has become a cornerstone of modern DevOps practices. The tool is widely used to automate the building, testing, and deployment of software, enabling teams to integrate code changes frequently and reliably.

Overview

Jenkins operates as a server-based system that runs in servlet containers such as Apache Tomcat. Its primary function is to monitor version control systems like Git, Subversion, or Mercurial for changes and then trigger a series of automated steps defined in a build script. These steps can include compiling code, running unit tests, performing static code analysis, and deploying artifacts to environments. The platform is highly extensible, with its functionality significantly augmented by a vast library of community-developed plugins. This architecture allows it to integrate with a wide array of development tools, including Docker, Kubernetes, AWS, Jira, and SonarQube.

History

The project originated as Hudson, created by Kohsuke Kawaguchi while he was an engineer at Sun Microsystems. A naming dispute arose after Oracle Corporation acquired Sun in 2010, leading to a fork of the codebase. The community voted to rename the fork to Jenkins, with the first official release under this name occurring in February 2011. Since the fork, development has been stewarded by the Jenkins community and commercially supported by companies like CloudBees. Key milestones include the introduction of Jenkins Pipeline in 2016, which provided a more powerful and durable way to define delivery pipelines as code, and the ongoing Jenkins 2 initiative which emphasized pipeline-as-code and other usability improvements.

Architecture

At its core, Jenkins follows a master-agent architecture. The central Jenkins controller (formerly master) manages the configuration, schedules builds, and serves the web UI. It can delegate actual build jobs to agent nodes, which are machines with different operating systems or environments, allowing for distributed builds across platforms like Linux, Windows, and macOS. Communication between the controller and agents is typically handled by the JNLP protocol or SSH. The system state and job configurations are stored on the controller's file system, though configurations can be managed as code using tools like Job DSL or the Jenkins Configuration as Code plugin.

Features

Key features include a versatile web interface for configuration and monitoring, support for Pipeline as code via the Jenkinsfile, and built-in functionality for scheduling jobs and generating detailed build reports. It provides native integration for popular version control systems and can trigger builds based on webhook events. The tool offers extensive security controls, including role-based access control and integration with authentication providers like Active Directory and GitHub. Its distributed build capability allows for efficient resource utilization, and its built-in artifact archiving facilitates the storage and retrieval of build outputs.

Plugins and ecosystem

The Jenkins Plugin Index hosts over 1,500 plugins, which are central to its adaptability. These plugins extend Jenkins to support building projects in virtually any language, including Python, C++, and Node.js, and to integrate with cloud platforms like Azure, Google Cloud Platform, and OpenStack. Notable plugins include the Blue Ocean plugin for a modern user experience, the GitHub Integration plugin for tight coupling with GitHub Actions, and the Kubernetes plugin for dynamic provisioning of build agents. The Update Center allows for easy management and installation of these extensions directly from the web interface.

Usage and adoption

Jenkins is extensively used by organizations of all sizes, from startups to large enterprises like LinkedIn, Netflix, and Uber. It is a fundamental component in implementing CI/CD pipelines, often in conjunction with Infrastructure as Code tools like Terraform and configuration management systems like Ansible. Its adoption is prevalent in industries ranging from financial technology to video game development. While facing competition from newer SaaS platforms like GitLab CI/CD, CircleCI, and Travis CI, Jenkins remains highly popular due to its open-source nature, flexibility, and powerful plugin ecosystem, maintaining a strong presence in both on-premises and hybrid cloud environments.

Category:Free software programmed in Java Category:Continuous integration Category:Build automation