What is Jenkins? Architecture and Characteristics

Continuous integration, testing, and delivery have become the norm for modern software development. These are important aspects of leading software development methodologies, may it be DevOps or Agile. There are numerous tools that make CI, CD, and CT easy, and one of them is Jenkins.

This blog is dedicated to Jenkins. It is a free-to-use automation server that makes continuous integration and continuous delivery easy and efficient. Let’s know more about it in the following section.

What is Jenkins?

Jenkins is an open-source Java-based server that may run on any platform. It lets you automate the continuous integration process by letting you run a series of commands. Servlet containers, such as Apache Tomcat, are used to execute this CI server.

It automates the aspects of building, testing, and deployment in software development, allowing for continuous integration and delivery. This allows developers to easily work on improving the product by introducing changes to the project.

Jenkins automates software builds in a continuous manner and notifies developers of mistakes as soon as they occur. An active community is one of the key reasons for its success. In addition to being flexible, the popular CI/CD tool has a thriving plugin ecosystem. It is capable of performing the following tasks:

• To generate software, it leverages build systems like Gradle and Maven.
• Automated testing is done with test frameworks like Nose2, PyTest, Robot, Selenium, and so on.
• Testing scripts can be run using Windows terminal, Linux shell, and so forth.
• Gather software test results and follow up with activities such as printing test reports and other similar tasks.
• Execute test scenarios with a variety of input combinations to increase test coverage.
• Continuous Integration (CI) is a process in which artifacts are created and tested automatically. This makes it easier to identify product flaws early in the development process.
• At the time of writing this blog, Jenkins blog had close to 1,500+ plugins donated by the community. Plugins allow you to customize your experience with the CD tool as well as provide support for expediting operations such as creating, deploying, and automating a project.

The History of Jenkins

Jenkins gets a head start in the competition because it has been in development since 2011. Kohsuke Kawaguchi created Jenkins (previously known as ‘Hudson’) while working at Sun Microsystems. Hudson was first released in February 2005, following its production in the summer of 2004.

Following Oracle’s acquisition of Sun Microsystems, the Hudson community approved a proposal to create the Jenkins project. In February 2011, Oracle decided that Hudson’s development should continue, therefore it was forked instead of merging with Jenkins.

Despite the fact that Hudson and Jenkins were developed independently, the latter accumulated many more projects and contributors than the former. As a result, the community no longer maintained Hudson.

The Release Process of Jenkins

Jenkins, like many other open-source projects, has two release lines: LTS (Long-Term Support) and Weekly (Regular). It is excellent at handling releases, with stable releases coming out every four weeks. The most recent LTS and Weekly versions of the automation server are 2.235.2 and 2.249, respectively.

Key Characteristics of Jenkins

Jenkins is more functionality-driven than UI-driven, thus there is a good learning curve to grasping what the open-source automation server is all about. It provides the following significant developer-centric features:

• Simple Setup and Configuration

Jenkins is a self-contained Java software that doesn’t care about the platform it’s running on. It runs on practically all popular operating systems, including Windows, various versions of Unix, and macOS. It comes as a standard installer as well as a .war file. Once it has been installed, it’s straightforward to set up the CD tool using the online interface.

• Open-Source Software

Since it is open-source, it’s completely free to use. The community is quite involved in its development, which makes it a very powerful CI/CD tool. You may get help from the giant, active community with anything connected to Jenkins, may it be extensions, usage, troubleshooting, or anything else.

• A Thriving Ecosystem of Plugins

The active community is the backbone of Jenkins, and members play a key role in the development (and testing) of nearly 1,500 plugins available for the free-to-use automation server in the Update Center.

• Convenient Distribution

Jenkins is built in such a way that distributing work across numerous machines and platforms for expedited building, testing, and deployment is extremely simple.

Jenkins Architecture

To understand how Jenkins works, we must first understand its architecture. It leverages a master-slave architecture to manage distributed builds. The interplay between the many aspects of the CI tool is detailed in the following steps:

• Developers update the source code as needed and commit it to the repository. A new version of that file will be created in the version control system that is used to maintain the source code repository.
• The Jenkins CI server keeps an eye on the repository for changes (in the form of code or libraries) and pushes them to the server.
• The next step is to see if the build with the ‘pulled changes’ is still progressing. The build server then executes a build with the code and generates an executable if the build process is successful. If a build fails, an automated email with a link to the build logs and other build artifacts is sent to the developer.
• If the build is successful, the created application (or executable) is uploaded to the test server. This stage facilitates the installation of continuous testing, which involves running a series of automated tests on the newly produced executable. Developers will be alerted if any functionality is lost as a result of the modifications.
• The changes and tested applications are automatically deployed to the production server if there are no build, integration, or testing issues with the checked-in code.

What is Jenkins Pipeline?

Jenkins Pipeline is a collection of plugins that help you set up and integrate continuous delivery pipelines into Jenkins. Through the ‘Pipeline Domain-Specific Language (DSL)’ syntax, Jenkins Pipeline also provides a collection of tools for designing basic and sophisticated delivery pipelines.

What is Jenkinsfile?

Jenkinsfile is saved as a text file. It explains how to set up and run a Jenkins Pipeline. The CD Pipeline is regarded as any other piece of code in Jenkinsfile, and it is versioned, committed, and reviewed just like any other piece of code.

Conclusion

Jenkins is a fantabulous CI/CD tool with a galore of features, and the best thing is that it’s free to use. We may infer that the automation server provides characteristics that increase release speed by offering CI services.

Jenkins Pipeline is a new tool that extends the capabilities of the CI/CD tool by allowing you to create a Pipeline as Code using DSL. Despite the fact that there are competing CI/CD technologies on the market, Jenkins thrives because of its active community and an excellent set of capabilities (especially Jenkins Pipeline), which provides faster feedback through CI tools.