Introduction to Continuous Integration

Software development and IT operations (DevOps) practices are crucial for effective software development life cycle (SDLC), and high quality of the products. Continuous Integration (CI) is a software development practice, that enables a team to integrate their changes continuously, and even multiple times per day. Ideally, each integration would be built and tested automatically, to detect, and prevent integration issues. This strategy reduces the occurrence of having to solve multiple and large code conflicts at once. In this post, I’ll describe how to enable Continuous Integration using Jenkins server.

The rapid growth of tech companies, size, and complexity of software solutions contributed to the need for CI and CD within the software development teams. Without CI, the integration is done manually, often with multiple procedures defined in workflows, and keep Integration Engineers focused on these tasks for most of their working time. This results in a decreased efficiency of engineers, because it is always an ongoing process, and it takes incomparably longer than developing and maintaining automated CI.

The proposed strategy is to use an automation server, with pipelines that reflect workflow procedures in the source code. Automation servers are a widely used solution, because of their flexibility to adjust to multiple workflows, and they can use private, and 3rd party tools, such as Python, Bash, and Perl scripts.

Software Development Life Cycle

Benefits of Continuous Integration

By incorporating Continuous Integration practices in the SDLC, you can drastically improve your development process and reduce bugs and errors in the final release. Continuous Integration also provides the following benefits:

• Improves code quality by detecting defects as early as possible in the development cycle.
• Increases developer productivity by automating the testing process and delivering new features faster.
• Maintains consistency across builds by identifying and fixing inconsistencies early in the process.
• Provides a clear audit trail of the entire development cycle.

Setting up a CI server using Jenkins

The first step is to install Jenkins on the machine where you’ll be running the build processes. There are several free and commercial options available, including Jenkins Community Edition, Jenkins Enterprise and Jenkins X (formerly known as CloudBees Jenkins). Regardless of which option you choose, you can follow the basic setup steps outlined below to install and configure your CI server. Once it is installed, you should modify the default settings to your specific requirements. You can configure the default credentials for your CI server using Jenkins Admin page. For additional details please refer to the official documentation.

Once you have completed the initial setup and installed a pipeline plugin, you can start creating your first project and adding test jobs to it. Create a Jenkinsfile in your Git repository, or write a declarative pipeline script in the Jenkins job configuration of your choice. You can then also create a build trigger or a cron job and schedule it to run at regular intervals. The build can then be executed automatically whenever you push changes to your repository. You can also create as many pipelines as you want and assign different projects to them so that separate teams can use the same CI server without the need for overlapping pipelines.

Jenkins automation server dashboard

Creating a Pipeline in Jenkins

Once your Jenkins server is installed and set up, you can create and manage automated build processes and tasks using Jenkins’ Pipeline feature.

Each pipeline requires:

• Steps, that are single tasks, for example queuing a test. They are a part of a sequence to define what should be done at this specific time. Steps can also work in a parallel,
• Node, that uses available executors on an agent, for example, the user can be an agent, but thebest practice is to set up an agent with permissions to execute pipeline steps because the entire workflow automation should be isolated. The node creates an isolated workspace that only lasts for the duration of a pipeline to ensure performance. It also schedules the steps that are defined in the pipeline source code, by adding them to the build queue, if an agent is free to work, it will start running the defined steps.
• Stages that can have multiple steps, used to compose the pipeline syntax.

Depending on the workflow and required actions, the pipeline allows to also implement:

• Additional workspace that will take another executor, especially useful if there are processingheavy tasks that can work in a parallel,
• Define functions that can be used multiple times to make the source code more readable, use Groovy in-built functions, for example, to match regular expressions, conditionals such as “when” and “if/else”. As Java is a parent of the Groovy programming language, the “try/catch/finally” block is also available,
• If required, the default environmental variables can be changed for specified steps, which can be used to change the build tool,
• Pipelines enable engineers to implement build parameters for variables and conditionals that can change from build to build.

It is important to mention that to use automated builds and tests in the pipeline, these solutions must be developed first. Commonly used tools for the build automation are Gradle and Maven, whereas examples of testing automation tools are LambdaTest, Katalon Studio, and Kobiton. The choice depends on the tech stack and the business rules of the project.

Sample workflow which can be automated using Jenkins automation server

Advantages of CI over traditional QA process

Unlike traditional QA processes that focus on manual testing of individual features, continuous integration focuses on testing the entire application every time a change is made. Using this approach, developers can rapidly identify and fix any bugs they discover before deploying the code to production. By eliminating the risk of releasing broken applications, continuous integration increases team productivity and delivers high-quality software on time.

Useful links

Jenkins homepage

Jenkins documentation

Atlassian’s take on Continuous Integration