CI/CD explained: Methods, tools, pipelines, and beyond

Making changes to source code doesn’t have to require manual, tedious, waterfall processes. Software development, testing, and security teams can leverage the continuous integration and continuous delivery (CI/CD) method to change, test, and deploy updates to the source code several times per day. This method relies on automation tools to streamline and optimize the individual stages that make up the approach.

CI/CD is a software development practice and method of delivery in a DevOps environment. The practice uses automation and continuous monitoring through the app development lifecycle to build applications more effectively and efficiently. Code changes are made more often, and teams operate off of a single repository. CI/CD is often credited with the more frequent delivery of apps to end users. 

CI and CD work together; they are not one and the same. CI optimizes the process of making code changes by automating the review of changes made to code. Developers can spend more time enhancing the code and less time manually reviewing it. CD automates the delivery of code to testing and deployment. You may also hear the term “continuous deployment.” It refers to the production of approved changes and uses automation to deploy these changes.

The pipeline is a key component of the CI/CD method. Rather than relying on manual, waterfall processes, the CI/CD pipeline has a sequence of stages designed to help test, deliver, and deploy code more efficiently. This approach is iterative and Agile in nature. The emphasis is placed on small, frequent changes to the code, which enhance its features and the overall functionality of the application. 

The CI/CD pipeline also plays a large role in delivering DevOps culture, as it requires a collaborative, team-focused working environment to be successful. This setup helps to decrease time-to-market and, in turn, increase customer satisfaction. CI/CD and DevOps work together to produce an Agile working style that centers around reducing obstacles, creating and responding to change, developing through rapid iterations, and delivering value to customers.

DevOps is an approach or philosophy that focuses on integrating software development and IT operations teams as well as automation to enhance the development life cycle. CI/CD, however, is a method or set of practices for developing and delivering applications, including code changes, for DevOps teams to follow. Both aim to break down barriers so that developers can respond faster to market opportunities, accelerate software deployment, and streamline operations. 

Ultimately, they’re two sides of the same coin. Where DevOps breaks down communication barriers between engineering and operations teams, CI/CD are crucial to deploying software to production. DevOps focuses on people, and CI/CD organizes the technology execution.

In traditional structures, software engineers and operations teams are siloed. With DevOps, they collaborate together and are cross-trained in related skill sets. The two teams share ideas, practices, processes, technologies, and a focus on delivering high-quality products. With a shared culture, these two teams are empowered to develop new products in a way that encourages rapid, continuous deployment.

CI/CD tools and methods, also called the CI/CD pipeline, take this to the next level by automating and monitoring the application lifecycle for greater reliability, even as DevOps teams accelerate their development timelines.

The way you set up your CI/CD pipeline is crucial to its success. While there are many ways to configure this pipeline, your CI/CD pipeline should follow four basic stages: source, build, test, and deploy.

The source stage begins when a change is made within the code repository. Examples of centralized repositories (aka version control systems) that organizations use include GitHub, GitLab, LaunchPad, and Bitbucket. Automated schedules, workflows, and other pipelines can also trigger the CI/CD pipeline. The way you set up your CI/CD pipeline is crucial to its success. While there are many ways to configure this pipeline, your CI/CD pipeline should follow four basic stages: source, build, test, and deploy.

After the code has been pushed to the centralized repository, the code and its dependencies are merged together. This is done through your continuous integration tool and is followed up by automated testing. You may also hear this stage referred to as the compilation stage. It’s required for languages such as Java, Go, and C++, but unnecessary for interpreted programming languages like Python. Software instances that do not pass this stage will need to be addressed by the team before moving on to the third stage.

Automated testing is used to identify any errors and issues with the code changes and the overall application. This stage may also include manual integration testing where testers verify that application features are functioning properly. Other tests that are often written by developers to be included in this stage include smoke tests and unit tests.

The deploy stage moves the code into a new environment like quality assurance (QA), pre-production, or production. This stage may be automated and will deploy the application to a live environment.

Throughout the CI/CD pipeline, teams use automation tools to test any changes made to the code and push them to deployment. CI/CD increased in popularity as development and operations teams looked for ways to build efficiencies in the development process and streamlined practices around large applications. The practice also reduces human error, optimizes the feedback process, and allows for the faster release of new features. 

There are several advantages to the CI/CD method, including:

• Speed. Smooth CI/CD pipelines enable teams to automatically build, test, and deploy features or code changes automatically using CI/CD tools. Not only can you address market shifts and customer requests faster, but you can respond quickly with bug fixes or security features.

• Reduced costs. Time is money. A CI/CD pipeline means your development teams can quickly respond to client demands, fix issues early, or avoid critical issues altogether, generating even more ROI.

• Improved user experience. With CI/CD, new features and changes are shipped on a continuous basis, ensuring the application meets changing user expectations and needs. 

• Errors caught earlier. CI/CD tools give QA engineers the ability to test, fix, and deploy new code in real time, so you avoid costly development delays.

• Collaboration. Development, testing, security, and operations teams work together through the CI/CD pipeline stages to improve the code and overall product. 

• Continuous improvement. The Agile nature of the pipeline means that immediate feedback is provided through automated testing. Developers can take in this feedback while it’s still top of mind to improve the quality of their work.

One of the most popular CI/CD tools is Jenkins, an open-source automation server. Its popularity lies partly in its flexibility and ability to run everything from a CI server to a CD hub. Jenkins also has a number of plugins available, so you can run CI from different environments. Because the CI/CD tool is open source, it’s regularly updated and kept up to speed with technical advancements. You can also use Jenkins with a variety of hosting environments, including on-prem, in the cloud, and on containers like Docker.

This beginner-level course will teach you how to use Jenkins and its features to automate critical tasks.

GitLab is another commonly used CI/CD tool. The open-source DevOps software can be installed pretty much anywhere including on-prem, in the cloud, on containers, and on Linux distributions. This configurability prevents a lot of headaches and costs for organizations. GitLab also contains some unique features such as Auto DevOps. With this feature, users can automate the detection, building, testing, and deployment of applications. You can also schedule deployment for specific branches to deploy.

• Travis CI: This CI/CD tool is designed to optimize DevOps testing across multiple environments and containers with greater security. 

• TeamCity: This Java, open-source tool integrates with Docker and Kubernetes.

• Concourse: Described as an “open-source continuous thing-doer,” Concourse takes a more general approach to CI/CD. 

• Buddy: Popular with web developers for its 15-minute configuration, Buddy supports all major languages and frameworks. 

• CircleCI: Use this adaptable CI/CD tool to build, test, debug, and deploy processes for CI. 

• Codeship: Known for its comprehensive control of CI/CD system design, you can automate workflows for development and deployment.