Continuous integration (CI) is the first phrase in an automated software release pipeline that allows developers to build, test, and merge code changes to an application in a central repository. CI enables developers to integrate small code changes frequently with the rest of the team.
Continuous integration works in tandem with continuous delivery (CD) processes. CD is the second phase of the software release pipeline, where code is released to a production environment in small increments. Altogether, CI/CD facilitates an effective process for getting products to market faster and allows the fast, easy deployment of new features and bug fixes.
Continuous delivery is often confused with continuous deployment. However, continuous deployment takes the automation process one step further, deploying updates automatically to a production environment without human approval. Continuous deployment is not a requirement of continuous delivery, but a further evolution of automated processes within the CI/CD pipeline.
While each step of the software development lifecycle (SDLC) can technically be done manually, CI and CD automate the processes of building, testing, and delivering code changes. The result is the CI/CD pipeline: a full set of development processes that run automatically when developers begin writing new code.
When the potential of a CI/CD pipeline is fully realized, developers can safely make consistent, incremental changes to application code daily or even hourly.
DevOps is a set of software development practices that enable organizations to deliver applications at a high velocity by bringing development and operations teams together. Under a DevOps model, the two are no longer siloed.
A modern CI/CD pipeline in DevOps has build, test, and deploy stages—and aims to automate as many of the processes within these stages as possible. Typical CI/CD pipeline stages include:
Source – The beginning of the CI/CD pipeline starts with a source code repository. Changes to source code can trigger CI/CD tools to initiate the pipeline, or the CI/CD pipeline may be triggered by automated scheduled work sessions or user-initiated workflows.
Build – This is where new code changes to applications are created and compiled to be prepared for the testing phase. Through CI, new code can be automatically queued for testing.
Test – The stage where new code is tested to prevent software bugs from reaching end users. Testing automation via CI can save developers tremendous time and effort. CI and automated tests provide faster feedback loops and more easily expose problems in new code that developers may not have foreseen.
Release – This is where CD comes into play to deliver new code to the application repository. Once new code has surpassed testing, CD can automatically send approved code to staging environments to prepare it for final release.
Deploy – In this stage, new code is deployed to a production environment for end-users either manually or automatically (continuous deployment).
Validation and Compliance – In DevOps, this is where IT and operations teams ensure stability, security, and quality of releases once they are deployed. Validation and compliance is an ongoing process as each new event triggers the CI/CD pipeline.
Getting started with a CI/CD pipeline in DevOps requires development, IT, and operations teams to collaborate on CI/CD technologies, best practices, and priorities. Once aligned, these teams can then begin to unlock the true benefits of CI/CD through an automated software release pipeline that ensures quality, security, stability, and a host of other benefits.
Frequent software releases are easier when code is developed in a continuously moving system. A well-functioning CI/CD pipeline keeps code continuously moving through test and deploy stages, so it’s always in a release-ready state—even when developers themselves aren’t around to work on it. By automating these phases of the development process, developers can focus on continual updates and release code more often in smaller increments.
The CI/CD pipeline allows thousands of developers to build code simultaneously, reducing the risk of breaking the build. Smaller releases and automated test cycles make it easier to isolate and eliminate bugs. Teams can also use feature flags to quickly disable individual functionalities—instead of the entire release—that aren’t yet ready or might cause an unexpected problem without using code.
The CI/CD pipeline makes it easier for DevOps teams to maintain and update applications. Automation streamlines testing and reduces the number of errors that can take place in many of the repetitive steps of the SDLC, and eliminates the need for manual requests or unnecessary back-and-forth between developers and operations teams. By updating small batches of code, the CI/CD pipeline saves on costs associated with bigger software releases in favor of scalable and sustainable updates.
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