How CI/CD Pipeline Works

[KodeKloud]

In the fast-paced world of modern software development, the ability to deliver updates and improvements to users quickly and reliably is a significant competitive edge. Rapid, consistent, and high-quality software delivery is not just a goal but a necessity, and this has led to the widespread adoption of CI/CD, key components of the broader practices of Agile and DevOps. 

The main idea behind CI/CD is to automate the software supply chain, enabling faster delivery of software to production. This not only produces code that is more secure and of higher quality but also facilitates faster feedback, ultimately leading to a quicker time to market for the product.

In this blog post, you’ll learn what a CI/CD pipeline is and how it works. Let’s get started!

What is a CI/CD Pipeline?

In the software development lifecycle, between developers writing software and users using it, the software typically goes through three key stages: build, test, and deploy. A CI/CD pipeline serves as a blueprint, providing a clear guide for the automated execution of these stages.

As the name suggests, a CI/CD pipeline consists of two parts: CI and CD.

CI 

The term CI stands for continuous integration. Whenever developers make any commits to a code repository, the CI portion of a pipeline builds and then runs tests and performs other checks on the code to ensure that it integrates well with the project’s stable code base.  

CD

The term CD can mean either continuous deployment or continuous delivery. It takes over once the CI processes are successfully completed.

Continuous deployment ensures that every change that passes the automated tests is automatically deployed to the production environment. Continuous delivery is the same as continuous deployment, with one exception: the final action of releasing to production requires human intervention.

How Does a CI/CD Pipeline Work?

A typical CI/CD pipeline has three fundamental stages: 

Build

Whenever developers complete a feature, fix a bug, or make any other significant code changes, they merge these changes into the main branch of the code repository. This branch represents the most current, stable version of the project.

Whenever a code commit occurs, the CI system automatically triggers a build process. This process involves compiling source code into executable or deployable artifacts. Depending on the requirements, it may include steps like bundling and other preprocessing steps necessary to create a version of the software that can be executed or deployed. 

The build step is essential because it verifies that the codebase is free of compilation errors. 

Note: Whether a build process is necessary and what it entails depends on the type of programming language used. For compiled languages such as C++, and Java, building is a crucial step that converts source code into executable binaries. For interpreted languages such as Python, the build process may include bundling scripts, managing dependencies, and setting application-specific configurations rather than traditional code compilation.

Test

After the build, the CI system automatically initiates a series of tests on the built software to check for errors, bugs, and other issues. The tests can include:

• Unit tests: These are automated tests that check the functionality of individual pieces of code.
• Integration tests: These tests ensure that different parts of the application work together as expected.
• Performance tests: These tests assess how the application behaves under various conditions, focusing on aspects like response times, scalability, and resource usage.

Note: In some contexts, certain types of tests might occur before the build stage, but these are generally limited to linting, static code analysis, etc. These tests don’t require the code to be built.

Deploy

Once the software has successfully passed through the build and test stages of the CI/CD pipeline, it progresses to the final and crucial stage: Deployment. 

This stage is where the verified and tested software gets delivered to various environments, including test, staging, and production. The choice of environment depends on the stage of the release process and the purpose of the deployment.

It’s important to differentiate between continuous deployment and continuous delivery within this stage. Under continuous deployment, every change that passes the CI portion of the pipeline is automatically deployed to the production environment. In contrast, under continuous delivery, the changes are ready for deployment and can be released to production, but there might be a manual step required for the final release. 

Note: In sophisticated CI/CD pipelines, the process often extends beyond the standard build, test, and deploy stages. For example, there can be a monitor and optimize stage, where metrics are collected and analyzed to eliminate risks and optimize release time. 

Benefits of CI/CD

Here are three key benefits of CI/CD:

#1 Enhanced software quality and reliability

Automated testing is a cornerstone of the CI/CD approach, playing a pivotal role in catching errors early in the development process. This early detection is crucial, as it not only maintains higher code quality but also significantly reduces the time and resources needed to address bugs later on. 

By identifying and fixing issues promptly, the approach ensures a consistent level of quality throughout the development cycle. Additionally, the automation extends to the deployment process, which further reduces human errors, a notable factor in software reliability challenges. This comprehensive automation guarantees that the software is not just of high quality but also consistently reliable and ready for release at any time with minimal risk of failure.

#2 Improved operational efficiency and collaboration

CI/CD automates the software development lifecycle, streamlining workflows from code integration to deployment. This reduces the time taken for each development cycle, enabling more work to be done in less time. Moreover, automation minimizes human-induced errors in the development process. Fewer errors mean less downtime and rework, which directly translates to increased operational efficiency.

Besides operational gains, CI/CD encourages different teams (development, operations, quality assurance, etc.) to work together throughout the development process. The ongoing communication between team members not only helps in identifying and addressing issues more collaboratively and efficiently but also helps in breaking down silos and fostering a culture of shared responsibility.

#3 Accelerated time to market 

CI/CD pipelines play a crucial role in reducing the time it takes to bring new features and functionalities to market. This acceleration is achieved by enabling small, steady, and frequent changes, which are much easier to manage and deploy than large-scale updates. By continuously integrating and delivering incremental updates, CI/CD ensures a constant flow of improvements to users, effectively reducing the time between ideation and availability.

Furthermore, the automation of the deployment process within CI/CD minimizes the manual effort involved in releasing new updates. This not only speeds up the process but also reduces the likelihood of delays caused by human errors. As a result, organizations respond more swiftly to market demands and customer feedback.

Tools to Build CI/CD Pipelines

There are many tools out there to help you build CI/CD pipelines. These tools can be broadly divided into three main categories:

• Cloud-managed solutions: Examples include AWS CodePipeline, Google Cloud Build, and Microsoft Azure Pipelines. 
• Open-source solutions: Tools such as Jenkins, GitLab CI/CD, and Spinnaker fall into this category. 
• Software-as-a-service (Saas) solutions: Examples of this category are CircleCI, Travis CI, and GitHub Actions.

Note that this list is not exhaustive but highlights some of the most popular tools in each category. The choice among these categories will largely depend on your organization's specific requirements, expertise, and the existing technology stack. 

Whether you prefer the flexibility and control of open-source tools, the robustness of cloud-managed solutions, or the convenience of SaaS offerings, there is a CI/CD tool out there that fits your project's needs.

Want to learn popular CI/CD tools? Check out our CI/CD learning path.

Conclusion

In this blog post, we learnt what a CI/CD pipeline is and how it functions, along with an overview of some popular tools we can use to build one. We covered the three common stages of a typical CI/CD pipeline – build, test, and deploy – and how they work together to ensure a smooth, efficient, and reliable software development process.

KodeKloud offers comprehensive courses designed to help you master popular CI/CD tools. Check them out below: 

• GitHub Actions: This is a course designed to help you master GitHub Actions. You’ll learn the concepts, workflow structures, and core components of GitHub actions. You’ll also learn how to create reusable workflows, custom actions, and self-hosted runners, along with a focus on security practices.
• Jenkins: In this course, you'll learn how to effectively use Jenkins, including the creation of pipelines and the utilization of different plugins. You'll also gain insights into Jenkins security and much more. Along with theoretical knowledge, the course provides hands-on practice to help you build a strong foundation in Jenkins.
• AWS CodePipeline: This course will help you gain a thorough understanding of CI/CD pipelines in the AWS cloud. You'll learn how to build and secure custom pipelines, integrate them with various tools, and manage their costs and limitations. The course includes practical exercises for a hands-on experience, equipping you with the skills to improve software release processes.

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