What is CI/CD? Definition, Process, Benefits, and Best Practices

Modern software development is virtually impossible without a CI/CD pipeline. However, for many newcomers to the IT industry, this topic still raises plenty of questions. In this article, NIX experts will explain the key aspects of CI/CD: from definitions to tools and best practices.

What is CI/CD?

CI/CD is a set of practices that significantly automate the processes of software development, code testing, and, most importantly, the deployment and delivery of products and updates to end users. The term CI/CD stands for Continuous Integration (CI) and Continuous Delivery (CD). These two concepts are foundational for all further automation.

To implement CI/CD, development teams create what are known as CI/CD pipelines. These pipelines contain clearly defined steps for every process: from creating a commit and changing code, to merging into the main branch and deploying into production environment, and beyond. The exact details of a CI/CD pipeline can vary from project to project, depending on the software being developed, the development team, available resources, and more. However, a basic software development lifecycle typically follows this pattern:

1. Work Planning: Management, development, and operations teams define the goals, methods, and tools for implementation. This applies to entire sprints and specific tasks related to new features.
2. Development: The core part of the work — actually making code changes based on the agreed plan, with requests for merging and processing by other developers.
3. Build: Once the new code is ready, developers create a build. During the build stage, new changes are integrated into the source code, and this is recorded in the version control system.
4. Testing: CI/CD involves not only developers but also QA teams. Ideally, this phase should involve comprehensive and, more importantly, automated code tests.
5. Deployment Process: Or, the deployment of updated software. Sometimes, the term Continuous Deployment is even used, but that’s a topic we’ll cover shortly.
6. Monitoring: After the deployment process, it’s crucial to monitor the service or application’s performance. This requires building a feedback collection system, which helps to fix bugs, optimize code, and add features. This, in turn, leads back to the first step.

While there may be variations depending on the project’s specifics, the key point is the repetition of processes in a loop. Software development must follow the principles of continuous integration, continuous testing, and continuous delivery. It’s no coincidence that the informal logo for this practice is often the infinity symbol.

The Essence of the CI/CD Process

Though this approach gained popularity only in the last 10-15 years, its essence is far from new. Development teams have long used version control systems like SVN, Git, and others. However, these only provide continuous integration of new code. Today, that’s no longer enough. You also need to automate the build and delivery of code into ready-to-use software or services. The combination of CI and CD enables high speed development, ensures repeatability of processes, improves software quality, and enhances the security of updates — all with minimal manual human intervention.

It’s worth noting that CI/CD isn’t strictly required for the software development lifecycle. Many developers find that a simple version control system is sufficient (though services like GitHub and GitLab do offer CI/CD capabilities). However, many professionals believe that without this automated process, it’s difficult to build large, complex projects that involve constant feature additions, updates, and code changes. For smaller products, continuous integration and continuous delivery might not be necessary. While there’s some logic to this, automating development, testing, and deployment still offers benefits regardless of a project’s size — such as helping to speed up time to market.

Differences Between CI and CD

While the set of methods known as CI/CD is often discussed together, it’s important to distinguish between continuous integration (CI) and continuous delivery (CD). This differentiation helps development and operations teams organize their work with the code at every stage of building and functioning within the CI/CD pipeline.

CI (Continuous Integration)

In traditional software development models, multiple developers work on code changes independently, and only when everything is ready do they merge the parts into a unified system. This approach has several issues. First, code releases take a long time. Secondly, code failures are almost always inevitable, requiring deep integration tests and bug fixes, which can lead to code conflicts. As a result, software updates are slow, bugs appear constantly, and customer satisfaction decreases. Continuous integration works differently. Every developer in the team works in their own code branch in the version control system, created for a specific task, and when ready, uploads the code to the master branch. The system includes automated testing to instantly detect conflicts, so developers can quickly address issues. The process is managed by a build server, which oversees the CI operations.

CD (Continuous Delivery)

Like continuous integration, the traditional software delivery model is manual, with the operations team handling all necessary code and environment procedures. This manual approach makes deployment a complex and time-consuming task, filled with checklists and bug-fixing. A continuous delivery pipeline eliminates these drawbacks. Developers only need to set up the system once using special tools, and from there, automation takes care of the rest. The CD process packages the code from the working repository, deploys it to a test environment, checks the new code for correctness, and, if everything passes, automatically deploys it to the central software repository.

While CI/CD pipelines are built on continuous integration and continuous delivery, some developers are now recommending another level of CD: Continuous Deployment. In this case, any code changes, even small ones, are deployed to production environments immediately after passing automated tests. This minimizes feedback time from users since developers no longer need to wait for common releases.

However, software development practice shows that continuous deployment is challenging to implement. Operations teams must ensure seamless automation of nearly all processes and develop a unique culture for working with code in the project. This requires considerable effort and control, but the work can be well worth it.

How CI/CD is Linked to DevOps

DevOps is a relatively new profession that emerged 5-8 years ago. The term is derived from Developers and Operations. DevOps engineers act as intermediaries between development and operations teams, facilitating the implementation of continuous integration, delivery, and deployment principles in projects. On a more granular level, DevOps teams ensure the infrastructure for CI/CD pipelines, handle automation, monitor processes at each stage, and consult with stakeholders.

DevOps engineers need to understand a wide range of areas, from coding and automated testing to network configuration. However, specialists are now emerging who focus on specific areas, such as LiveOps (responsible for maintaining production environments), SysOps (who manage infrastructure), SecOps (addressing security infrastructure issues), and CloudOps (working with cloud infrastructure). That said, this is a topic for another discussion. We recommend reading more about what is DevOps in our article.

Key Benefits of CI/CD

In general, several benefits of implementing a CI/CD pipeline in software development were already discussed above. However, in reality, there are much more. In this section, we have gathered only the most significant benefits of continuous integration and delivery.

• Increased Efficiency. Thanks to automation, development velocity is boosted as teams spend less time on routine tasks like setting up environments, handling bug fixes, and deploying projects. This means specialists will switch contexts less often, allowing them to focus more on their core work with the code. As a result, developer productivity on the project increases.
• Reduced Risk of Defects. In traditional development models, many bugs — especially simple ones related to typos and carelessness — survive until main testing. This distracts QA teams and developers, especially if the errors make it into the release. With CI/CD, these bugs are detected almost immediately after they appear in the code.
• Faster Product Deployment. Automation accelerates processes. But in the case of continuous delivery, the benefit is not just in task execution by tools instead of humans. More importantly, CI/CD pipelines allow new features to be released as soon as they are ready. Traditional releases do not happen every month, but with continuous deployment, updates can be launched daily.
• Increased Logs. Any software development model must have monitoring for code changes, testing, deployment, and performance. But in this practice, everything is taken to the next level. It’s impossible to imagine it without tools that track literally any changes in the behavior of teams and products. This allows for a much clearer understanding of the problems that arise, where, and why.
• Quick Rollback. Thanks to continuous integration and delivery, you can easily revert to a previous version if something goes wrong during an update. Developers frequently merge code, so it’s crucial to be able to roll back quickly, whether the issue is a code conflict or a problem in the production environment. With just a few keystrokes, you can return to a stable build.
• Simplified Planning. Traditional models are not flexible. As a result, development and operations teams often spend a lot of time building plans and creating backup scenarios in case something goes wrong. In contrast, a CI/CD pipeline is a more attractive solution. It’s inherently adaptable to the changing conditions of modern business and the emergence of new features.
• Improved Code Checks.  Continuous testing is a dream for any product owner, ensuring that most issues are caught during the software development phase. It’s also easy to implement integration tests, unit tests, and other types of tests. And all of them will be automated!
• Cost Efficiency. With faster releases, streamline workflows, and improved software quality, the economic benefits are clear. By implementing such approaches, development costs decrease. At the same time, the product itself has a better chance to market faster and become successful among users.

Top Best Practices for CI/CD

Building, using, and monitoring a CI/CD pipeline is a complex task. Listing every single best practice would take a lot of space, but here are a few of the most popular, useful, and interesting tips that could be valuable when you’re preparing for DevOps interview questions. 

• Commit Code Daily.  Developers shouldn’t wait to merge big batches of changes into the master branch. Even small code changes and updates should be committed in small batches regularly to reduce the complexity of conflicts. Avoid creating too many branches for individual tasks, as it complicates version control. But also, don’t generate new releases too frequently — this can clutter the production environment.
• Automate Testing as Much as Possible. Manual intervention always comes with the risk of mistakes, especially in continuous testing. The more tests you can automate, the better. This is not just a job for QA teams — DevOps teams should also get involved in this process. With their knowledge, they can help create entirely new test scenarios.
• Run Parallel Tests. CI/CD pipelines should function like conveyors, so running similar tasks simultaneously is a normal practice. You should run multiple checks for code changes in parallel to save time. If infrastructure resources are limited, sort tasks by priority — start with the simple, quick tests to increase efficiency. Cloud infrastructure can also help with automated testing.
• Ensure Clean Test Environments. For each testing iteration, create new containers. This way, the results of your automated tests won’t be affected by the residual effects of previous runs. Clean, disposable environments reduce the influence of various host environments on the final results. Additionally, these containers will allow you to integrate various components using standard APIs.
• Use Version Control. This is a basic but crucial recommendation that should almost become a project culture. Modern software development relies on systems like GitHub, GitLab, and BitBucket. So, whenever errors or conflicts are detected during testing in the new version, immediately roll back to a stable version. This allows you to analyze the cause of the issue, and keep the other processes running smoothly.
• Consider Code Migration. Migrating new code changes between development and production environment is a difficult and tedious task. It distracts developers from their core work and carries risks.  So, it’s better to simplify this process through automation. You can use special scripts to handle code migration and add them to your project’s infrastructure.
• Eliminate Deviations from CI/CD. The principles of continuous integration, delivery, and continuous deployment should apply to every task without exception. This process should be one-way and streamlined. You must ensure that no task involving code changes is done outside of the established pipeline. Otherwise, you run the risk of introducing problems into other levels of the process or even production.
• Monitor Feedback Continuously. Continuous feedback is just as important as continuous integration and continuous deployment. Constantly collecting data about the code and app’s performance will help you ensure the reliability of your automation and development teams. All reports should be structured, with clear goals and actionable insights. This way, you can truly improve both continuous testing and code writing.
• Guarantee Process Transparency. This is one of the key factors for the successful implementation of CI/CD. Without transparency, it’s impossible to build effective communication and collaboration between different specialists, ensure the reliability of tests, and maintain development speed. Therefore, DevOps engineers should promote transparency across teams. For example, by providing regular updates on test results, process flows, and more.
• Select Optimal Tools. No matter how well-built the pipeline is or how responsibly all involved specialists work, continuous integration and delivery won’t be effective if you’re not using the best tools. Choose your tools carefully — there’s a wide range of powerful services and software out there for every aspect of CI/CD. Pick the ones that best fit your project’s needs.

DevOps Tools

Listing all possible tools for working with the DevOps environment is impossible — there are just too many. But here are a few of the most popular programs that can optimize the execution of key tasks in DevOps teams:

• Ansible. This tool helps manage configurations and scale them for hundreds of servers, environments, and applications. For remote devices, Ansible supports SSH, which is not always available in its counterparts. It’s easy to manage the tool thanks to its declarative markup language and YAML.
• Terraform. With this service, you can quickly create and configure infrastructure automatically. This includes virtual machines, storage, load balancers, and cloud services like AWS, Azure, and GCP. Management is done using a declarative language with HCL and JSON.
• Jenkins. An open-source tool for simplifying CI/CD implementation. It has numerous integrations with a wide variety of tools and services through plugins. This includes version control systems, deployment tools for different environments, testing frameworks, and more.
• Docker. A platform that simplifies continuous deployment and environment management. It allows you to package applications into containers with everything needed for running, from dependencies and libraries to configuration files.
• Kubernetes. A container orchestration service that automates the management, monitoring, and tracking of containers. This tool integrates with Terraform, Jenkins, and Docker (including Docker images), and supports cloud services like AWS, Azure, and GCP.

These tools are just the tip of the iceberg. They also need skills in system administration (Linux and Windows), knowledge of Python and Bash, and an understanding of cloud platforms like AWS, Azure, or GCP. However, experienced experts say: it’s not about knowing the buttons, it’s about understanding the principles. With that knowledge, learning new tools that emerge daily in the DevOps space becomes second nature.

How to Learn More About CI/CD and DevOps

We could talk about building and operating CI/CD pipelines for days — there’s enough content for a whole series of articles. But you can’t truly master it by reading alone. To really learn, you need a structured program, experienced mentors, and practical tasks. And that’s exactly what you’ll find at NIX’s completely free DevOps course. What’s more, after successfully completing the course, you’ll be eligible to apply for DevOps vacancies on our team. With NIX, you get maximum opportunities for a confident start in the IT industry — join us!