How CI/CD Pipeline Works
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.
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, test, and deploy.
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.
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. The manual step ensures that all technical, business, and regulatory requirements are met, and that the software is deployed in the most strategic and safe manner possible.
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
Below are some of the benefits you get from adopting CI/CD:
- Faster delivery: Automation streamlines the entire application lifecycle, making faster releases possible.
- Improved quality: Frequent merges and deployment coupled with automated testing help improve overall code quality.
- Increased productivity: Developers spend less time on non-coding tasks and more time writing code.
- Better visibility: Automated builds provide visibility into the progress and health of development pipelines.
- Reduced risks: Integration issues are identified quickly, thanks to CI, and the risk of defects reaching production is reduced with CD.
Easy collaboration: Shared code repositories facilitate collaboration between teams and individuals.
Top 10 CI/CD Tools You Should Learn
Below are the top 10 most popular CI/CD tools:
#1. GitHub Actions
GitHub Actions has been making waves in the CI/CD space, and for good reason. This robust, cloud-native platform seamlessly integrates with the GitHub ecosystem, allowing developers to automate a wide range of tasks, from building and testing to deploying their applications. What sets GitHub Actions apart is its ease of use and the vast community of developers who have created pre-built "actions" (think of them as reusable building blocks) that can be easily incorporated into your workflows.
One of the key advantages of GitHub Actions is its flexibility. Whether you're working with a simple Node.js application or a complex, multi-service infrastructure, GitHub Actions can be tailored to fit your needs. Additionally, the platform's support for a diverse range of programming languages and cloud providers makes it a versatile choice for teams with diverse technology stacks.
Check out our course on GitHub Actions to learn more about this tool
#2. FluxCD
FluxCD, a GitOps operator for Kubernetes, is an open-source tool that automates the deployment of applications on Kubernetes clusters. Its focus on immutable infrastructure and automated releases has increased its popularity among DevOps engineers.
FluxCD's declarative configuration and event-driven architecture make it an ideal choice for managing containerized applications on Kubernetes.
As Kubernetes adoption continues to soar, I expect FluxCD to become an indispensable tool for DevOps professionals working with containerized applications.
To learn more about this, check out our course: GitOps With FluxCD.
#3. GitLab CI/CD
GitLab has long been a leader in the version control and DevOps space, and its CI/CD offering is no exception. GitLab CI/CD is a powerful, end-to-end platform that seamlessly integrates with the broader GitLab ecosystem, enabling teams to manage their entire software development life cycle within a single, unified interface.
What makes GitLab CI/CD stand out is its robust feature set and its customization level. From advanced testing and security scanning to built-in support for Kubernetes and container orchestration, GitLab CI/CD provides a comprehensive solution for teams of all sizes. Its intuitive, web-based interface and extensive capabilities make it one of the top CI/CD tools you should learn.
Check out our course GitLab CI/CD: Architecting, Deploying, and Optimizing Pipelines to learn more about this tool.
#4. Jenkins
While not the newest kid on the block, Jenkins remains a stalwart in the CI/CD landscape. This open-source automation server has been a go-to choice for developers for over a decade, and its longevity is a testament to its reliability and extensibility. Learn How to Automate CI/CD Pipeline Using Jenkins.
One of the key advantages of Jenkins is its vast plugin ecosystem, which allows you to tailor the platform to your specific needs. Whether you're looking to integrate with your favorite cloud provider, run security scans, or trigger deployments based on specific events, there's a Jenkins plugin for that. Additionally, Jenkins' flexibility in terms of deployment options (on-premises, cloud, or containerized) makes it a versatile choice for teams with diverse infrastructure requirements.
Enroll in our top-rated Jenkins course to get started with this popular CI/CD tool.
#5. Jenkins X
Jenkins X, a project by the creators of Jenkins, aims to simplify the CI/CD process for Kubernetes and modern cloud-native applications. With its opinionated approach to automating application build, testing, and deployment, Jenkins X offers a compelling solution for DevOps practitioners working with Kubernetes.
Jenkins X's integration with GitOps and its emphasis on promoting best practices make it a valuable tool for DevOps professionals working in cloud-native environments.
While Jenkins is a more general-purpose CI/CD tool, Jenkins X is a more specialized and automated tool for cloud-native application development.
#6. CircleCI
CircleCI is a cloud-based CI/CD platform that has gained significant traction in recent years. What sets CircleCI apart is its focus on developer experience and its ability to deliver fast, scalable, and reliable builds.
CircleCI's intuitive configuration language, which is based on YAML, makes it relatively easy for developers to set up and manage their CI/CD pipelines. Additionally, the platform's support for a wide range of programming languages, cloud providers, and container orchestration tools ensures that it can be seamlessly integrated into a variety of development workflows.
One of the standout features of CircleCI is its performance optimization capabilities. The platform's intelligent caching and parallelization features can help to significantly reduce build times, ultimately accelerating the deployment of your applications.
#7. Azure DevOps
Microsoft's Azure DevOps is a comprehensive DevOps platform that includes a robust set of CI/CD tools. While it may not be the first choice for teams outside of the Microsoft ecosystem, Azure DevOps has been steadily gaining traction, particularly among enterprises and large organizations.
The key strength of Azure DevOps lies in its seamless integration with other Microsoft products, such as Visual Studio and Azure. This tight integration can be especially beneficial for teams that are already heavily invested in the Microsoft technology stack because it allows them to manage their entire software development life cycle within a single, unified platform.
In addition to its CI/CD capabilities, Azure DevOps also offers a range of other DevOps-related features, including version control, work item tracking, and automated testing. This comprehensive approach can be particularly appealing for organizations looking to consolidate their toolchain and streamline their overall DevOps workflows.
To learn more about this tool, check out this blog: What Is Azure DevOps: Everything You Need to Know.
#8. AWS CodePipeline
While AWS CodePipeline is exclusively available on AWS, it offers a Jenkins-like experience without the operational overhead of self-hosting. For organizations that rely on AWS services, CodePipeline provides a compelling, fully managed, continuous delivery option.
However, concerns around lock-in may give some pause depending on infrastructure strategies. Still, CodePipeline offers AWS-focused firms a smoother modernization path for DevOps practices worth consideration
Learn more about this tool in our AWS CodePipeline course
#9. ArgoCD
Argo CD is a declarative GitOps continuous delivery tool for Kubernetes. It helps automate applications' deployment to Kubernetes clusters by using a Git repository as the source of truth for defining the desired application state. This way, changes to the application can be made through code and be version-controlled, promoting a more predictable and auditable deployment process.
Rather than one-off runner jobs, Argo CD fosters a model of continuous deployment that aligns well with industry best practices.
Learn more about this tool in our GitOps with Argo CD.
#10. Harness
Harness, a newer CI/CD market entrant, offers a unified platform supporting Continuous Integration and Continuous Deployment. Its emphasis on ease of use, automation, and security has attracted many users since its inception.
Harness' visual pipelines and templating features allow for efficient and maintainable configuration of complex CI/CD workflows. Although Harness is a paid solution, its generous free tier and impressive feature set make it an attractive option for teams looking to streamline their workflows.
KodeKloud offers comprehensive courses designed to help you master popular CI/CD tools. Check out these courses in 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.
