What is continuous integration/continuous delivery (CI/CD)?

CI/CD provides organizations with a modern development framework that enables faster, more reliable code integrations, software releases and upgrades. CI/CD approaches form an automation pipeline—called the CI/CD pipeline—that consists of three key processes:

• Continuous integration (CI). CI is a software development practice in which developers regularly integrate new code into a central source code repository throughout the development cycle.

• Continuous delivery (CD). CD practices automate the packaging and delivery of code changes after they have passed integration tests. It keeps code in a deployable, “evergreen” state, so developers can release code packages on demand.

• Continuous deployment. Mature CI/CD pipelines also rely on continuous deployment, a development strategy that enables developers to automatically release code changes into the production environment.

CI/CD represents a significant modernization of software development practices, which used to require manual workflows and rigid, sequential phases. Traditional methods were suitable for smaller development projects, projects with stable requirements or projects where regulatory environments demanded predictability.

But today’s software applications move and change quickly. They exist in cloud-based environments and require a development approach that facilitates frictionless collaboration, rapid feedback and adaptability to changing requirements.

CI/CD tools provide just that. They enable developers to build fast, agile, reliable software applications, which is essential for meeting customer needs and maintaining a competitive advantage over competitors.

CI/CD strategies and tools enable developers to transition away from the cumbersome, and often tedious, manual processes that accompany traditional development.

Traditional development follows a linear, sequential process, where each stage—requirements gathering, design, coding, manual testing and deployment—must be completed before the next begins, even if there are lengthy gaps between each phase.

Each developer was responsible for manually integrating code into new iterations of an app or service. Different pieces of code didn’t always work well together, and developers integrated their changes on different timelines (sometimes at the last minute), so integration was a time-consuming, error-prone process, especially for large development teams.

Software testing was also infrequent. Teams typically implemented large batch updates all at once (often after code implementation), which allowed bugs to slip through the cracks and accumulate in the codebase. When issues arose, developers struggled to figure out which change introduced the issue.

As a result, teams encountered more challenging debugging and quality assurance tasks, higher failure rates and slower code releases; users saw more software errors and glitches; and businesses lost revenue to process inefficiencies.

CI/CD automates most aspects of building, testing and releasing software. Automated pipelines implement continuous integration, testing and deployment throughout the development lifecycle, improving pipeline efficiency and reliability.

Code changes are continuously and incrementally merged into a shared repository, automatically built and tested after each commit, and quickly deployed (sometimes multiple times daily). Small changes and frequent code commits enable developers to catch issues earlier and perform rollbacks more easily.

With CI/CD tools, teams immediately know the results of each commit, and everyone can see the status of every build, test and deployment. These features help increase pipeline transparency for development and operations teams and simplify inter-team collaboration.

Continuous integration is the first part of a CI/CD pipeline. It enables DevOps teams to continuously improve their software applications, receive consistent feedback, catch and fix errors before they affect software performance, and deliver higher-quality software on more predictable delivery schedules. 

Developers submit code changes to a shared or main branch of a version control system (Git, for example) to track code changes over time, and the submission triggers a CI tool to perform a “build” of the updated code base. The CI system grabs the new code, compiles it with existing code and packages it with any dependencies, such as configuration files, libraries or other resources. This constitutes “the build.”

Testing tools run a battery of tests to validate the build before a “build artifact”—the resulting file that is passed along for further testing or to a production environment—is produced. This next part of the pipeline is referred to as continuous delivery.

Continuous delivery (CD) picks up where continuous integration leaves off, automating the delivery of applications and validated code base changes (updates, bug fixes and even new features) to all necessary infrastructure environments for further testing.

Code builds that pass integration tests and validation stages are packaged and delivered to code repositories, which centralize and store code packages in a deployable state. CD workflows test both the software and any dependencies, such as connected application programming interfaces (APIs), to identify and correct any errors.

The code is validated to help ensure that the software works across scenarios, and if it passes validation, the system notifies DevOps teams that the latest build is available. Team members have the opportunity to provide feedback about the new build and make any final suggestions for changes.

Though most CD processes are automated, CD requires teams to manually approve a build before exposing it to end users in a live production environment. This feature enables developers to perform risk-controlled software releases, keep builds ready to ship, and make sure that bugs and test failures are caught before production.

Continuous deployment takes CD a step further by automatically deploying every approved change to production, without human intervention. At this point, code modifications have passed all the necessary testing protocols and are therefore ready for the release process.

When code updates are tested, validated and approved, continuous deployment systems move the software artifact to a pre-production staging environment or to public servers and distribution platforms (such as application stores) where users can access it.

Continuous deployment tools offer several benefits for enterprises looking to scale applications and IT portfolios. Above all, they speed up time-to-market by minimizing the lag time between coding and customer value.

DevOps teams sometimes complement continuous deployment services with other deployment control tools, such as feature flags, which enable developers to turn features on or off without modifying or redeploying source code. 

The CI/CD pipeline is an automated workflow that streamlines software development by integrating, testing and deploying code continuously. It moves code end-to-end—from development to production—helping ensure that software updates are delivered quickly, safely and reliably.

A typical CI/CD pipeline consists of several automated processes and stages across a software release lifecycle, including:

CI/CD is a fundamental part of DevOps, but it only represents a subset of DevOps practices.

DevOps is a framework that outlines both a software development process and a culture shift toward coordination and collaboration between software development team and IT operations teams. Traditionally, these two groups operated separately from each other. In the DevOps methodology, they work as a collaborative team with a set of shared tools and practices.

A DevOps approach promotes shared responsibility, continuous collaboration and process optimization. In addition to the software delivery pipeline, its scope covers infrastructure and platform engineering, security, compliance, governance and risk management.

By contrast, CI/CD specifically focuses on building, testing, deploying and improving software applications. Automating these processes enhances DevOps by helping organizations improve code quality, test coverage, dependency management and observability metrics, and ultimately, release stronger software more often.

CI/CD security requires practices, processes and technologies that can incorporate security and compliance measures throughout the pipeline.

In traditional development models, security was often tacked onto software at the end of the development cycle. But the advancement of cloud platforms, microservices architectures and containerized applications has changed (and accelerated) the software development lifecycle, rendering traditional security strategies obsolete.

Enter DevSecOps.

DevSecOps—short for development, security and operations— incorporates cybersecurity architects and engineers into the DevOps strategy to make sure that every app component and every configuration item in the stack is proactively patched, secured and documented. It is a development practice that shifts security protocols from the right (end) to the left (beginning) of the development pipeline.

With shift left, team members implement security protocols (such as data encryption, input validation, role-based access controls and multifactor authentication) from the outset. Shifting left enables DevOps teams to quickly identify and remediate security vulnerabilities before cybercriminals can exploit them or disrupt software functionality. 

DevSecOps also incorporates “shift right” activities, extending security practices into post-deployment production environments. Shift-right practices prioritize monitoring, testing and protecting applications at runtime under real-world conditions. They complement shift-left security by creating a continuous feedback loop where security issues discovered in production help inform earlier development phases.

Used together, shift-left and shift-right security enable enterprises to integrate security controls into every phase of an application’s lifecycle. This dual “shift-everywhere” security strategy helps DevOps teams implement both early prevention and post-deployment threat detection and response, enhancing the overall security posture and driving continuous improvement.

Several key trends and technologies are shaping how software applications are built, managed and secured in CI/CD pipelines:

AI-powered CI/CD solutions can help developers build more dynamic, more secure, more scalable applications.

An organization can use AI and ML tools to continuously monitor software code in real time to identify security risks and quality issues. If these tools detect an anomaly, they can trigger automated workflows to address the problem. Such a tool might, for example, restart a failed service or provision additional resources to accommodate an increase in user demand.

And unlike static, threshold-based anomaly detection methods, AI models leverage contextual and historical data to forecast potential pipeline failures before they occur. Forecasting features empower DevOps teams to take a proactive approach to application management, preventing downtime and outages before they occur.

Furthermore, ML algorithms can help teams optimize continuous testing processes. For example, organizations can use ML tools to identify and repair flaky tests (tests that unpredictably pass or fail) and automate test case generation by analyzing code changes, past defects and user behavior. According to the IDC, more than 90% of businesses are using, experimenting with or expanding their use of AI and ML tools in their software testing practices.

Infrastructure provisioning (which involves hardware setup, OS installation and network configuration by specialized staff) can create bottlenecks. Developers can deploy application code in minutes, but it might take hours or days to set up infrastructure.

Infrastructure as code (IaC) is “a DevOps practice that automates the provisioning and management of IT infrastructure by using configuration files rather than manual processes.” Because IaC treats infrastructure as software, it enables infrastructure to move at the speed of software development.

Teams can use IaC to version, test and deploy infrastructure by applying the same templates and practices they use for application code. In fact, infrastructure and application code can be tested, validated and deployed in parallel (instead of using disparate processes).

Developers can quickly provision sandbox environments (secure, isolated environments where teams can test and run code without affecting live applications) and production environments on demand. QA teams can spin up test environments instantly, with consistent configuration. Operations teams can automate infrastructure for user-acceptance and security testing.

And when new code passes testing, both the application and its infrastructure can be deployed together, resulting in faster feature delivery and more frequent deployments.

GitOps is a modern operational framework that helps accelerate software delivery by applying developer-centric coding practices (such as pull requests and code reviews) to infrastructure operations and software configuration practices.

IaC is central to GitOps. IaC defines and manages infrastructure through code and declares the desired state of systems. These IaC configurations are often stored on Git-based platforms (GitHub, for example), with a Git repository serving as the single source of truth for storage and version control. In a CI/CD pipeline, automated agents continuously check the repository for changes and apply the configurations to live (deployed) systems.

For example, if a DevOps team wants to deploy a new microservice, they would make the necessary changes to the Git configuration files. Deployment tools will review and validate the updates before merging them with the main code branch. Then, CI/CD pipelines apply the changes to the live infrastructure (a Kubernetes cluster or Docker container, for instance) so that the deployed environment always matches repository definitions.

GitOps enables teams to deploy code updates multiple times per day with the knowledge that Git tools will quickly detect and correct any discrepancies. As such, GitOps can help DevOps teams further reduce manual intervention and minimize CI/CD pipeline complexity.

Even in a DevOps environment, many software developers find themselves overwhelmed by the diversity and volume of work that falls under their purview, especially when it requires them to complete manual, repetitive tasks. More than three-quarters of developers spend at least 30% of their time on such tedious tasks.

Serverless computing is a development environment and execution model that abstracts infrastructure management away from developers. A cloud service provider provisions and manages all servers, backend infrastructure components and runtime environments, so developers can focus on application code.

Serverless platforms support event-driven workflows—where code commits or pull requests trigger automated builds, tests and deployment steps—to further automate the CI/CD pipeline.

CI/CD systems offer organizations a range of benefits, including:

• Better software quality. CI/CD pipelines prioritize continuous code and software testing so that bugs and vulnerabilities are caught early in the development processes and developers can deliver higher-quality code.

• Faster time-to-market. CI/CD enables faster software deployments that reduce the lead time between code commits and software delivery from weeks to minutes.

• Less risk and downtime. Small, frequent code updates make bugs and errors easier to resolve, preventing large-scale outages and reducing mean time to repair (MTTR).

• Greater transparency. CI/CD dashboards and continuous feedback loops help ensure that DevOps teams have access to all the information they need at all times, improving transparency and accountability.

• Increased productivity. CI/CD pipelines automate repetitive, manual steps (troubleshooting builds and managing deployment scripts, for instance), so developers can focus on updates, new features and new applications.