What Is CI/CD?
CI/CD is a software engineering approach that combines continuous integration (CI) and continuous delivery or deployment (CD) into an efficient and fast pipeline. It facilitates rapid and accurate software release, streamlining the build and delivery phases of the software development lifecycle. It typically involves utilizing automation to rapidly release high-quality software.
1. Continuous Integration
The objective of a modern software development pipeline is to allow multiple developers to collaborate on the same application, working simultaneously on multiple features. However, many organizations rely on a traditional manual development and branching approach where developers merge all the code in a single day. This approach results in tedious, time-consuming workloads.
When developers work in isolation, any changes they make to an application risk conflicting with other changes made simultaneously. When each developer or team builds features in isolation, and these features are only integrated at the end of the development cycle, there is no guarantee they will work together. Integration becomes a difficult and time-consuming step of the process, which can be eliminated.
Developers can frequently merge code changes into the shared branch with minimal compatibility issues with continuous integration. Once the CI system merges the changes to the application, it automatically builds the application and validates the changes via various automated tests. These include integration and unit tests to verify that the changes don’t break the app. Tests should cover everything from functions and classes to the application’s various modules. If an automated test discovers a conflict in the code, the team can fix it quickly and easily.
2. Continuous Delivery
Continuous delivery allows development teams to deliver packaged artifacts into the production environment. CD solutions automate the overall delivery and deployment process. CD can handle infrastructure provisioning, ticketing (change management), artifact deployment, monitoring, and verification to prevent bugs from reaching production.
Organizations can leverage continuous delivery to facilitate the management of their operations. For example, an IT admin team might use a CD pipeline to provision the deployment infrastructure. CD pipelines can also orchestrate the infrastructure setup using a configuration management automation tool like Ansible or puppet.
The CD pipeline deploys all changes automatically once the code passes the necessary tests built into the CI/CD pipeline. However, the organization maintains control over the deployment, including the timing, unlike in a continuous deployment pipeline.
Related content: Read our guide to continuous delivery
3. Continuous Deployment
Continuous deployment takes continuous delivery a step further by directly releasing all code changes to the customer once they pass the production pipeline’s stages. It eliminates human intervention by ensuring that new changes cannot reach production if they fail a test.
Continuous deployment is useful for accelerating the customer feedback loop, taking pressure off the development team by eliminating the concept of a single release day. The developers don’t have to handle deployment – they can focus their efforts on building code and see the changes go live within minutes of committing them.
Related content: Read our guide to continuous deployment
4. CI/CD Pipeline
A continuous integration/continuous delivery pipeline is a DevOps workflow that emphasizes frequent, reliable delivery processes. This agile methodology relies on iterative, not linear, processes, allowing development teams to build, integrate, test, release, and deploy software quickly as part of a collaborative project.
Automation is a core aspect of CI/CD pipelines. It helps ensure code quality while reducing the operational burden on the DevOps team. Automated tests filter each software change through the pipeline, identifying issues and dependencies. Automated pipelines can also push changes to various environments and deliver the application to production.
Automation aims to conduct quality control and assess the code’s performance, API usage, and security. It ensures the comprehensive integration of all changes made by developers, guaranteeing correct performance. By automating the different stages of the development process, a CI/CD pipeline can help the DevOps team complete tasks faster and ensure high code quality.
Every CI/CD pipeline is unique, based on the specific needs of the organization and project. However, most pipelines use processes and tools that fall into the following categories:
- Version control and source code management – the developer initiates the entire pipeline when committing a new change to the source code repository. Common repositories include GitHub and SVN, which help teams incorporate versioning into the CI/CD pipeline.
- Build server – a dedicated build or CI server builds binaries from the source code when a developer makes a commit.
- Testing – once the pipeline builds the code, it passes it through a series of tests to verify its readiness for deployment. These should ideally be automated tests, although manual tests are common before deployment.
- Deployment – after the code changes have passed all the tests, they can progress to a staging or production environment (this varies depending on the project). The pipeline may deploy the changes to a single production server, distributed environments, or Kubernetes production cluster.
CI/CD pipelines often incorporate other processes and tools to enable observability, management, and bug fixes
Related content: Read our guide to CI/CD pipeline.
5. CI/CD Tools
CI/CD tools enable you to automate repetitive tasks across the software development lifecycle, including testing, deployment, and maintenance. These tools facilitate collaboration between software engineers, allowing teams to create tasks and track CI/CD processes.
Common types of CI/CD tools are:
- Continuous integration tools
- Deployment automation tools
- Continuous delivery platforms
- GitOps platforms
- Container orchestrators
- Workflow automation tools
Related content: Read our guide to CI/CD tools
6. Artifacts and Services
Each service is self-contained software that works as part of a group of services within an application. Common examples include standalone Docker containers, a single Node.js application, and Kubernetes pods.
An artifact is a service built, packaged, and ready for deployment. Each service has unique deployment requirements. For example, a Node.js application requires packaging services in a certain way for deployment. This ready, packaged state is an artifact.
7. Stages and Workflow
Once you start a deployment, each artifact goes through various stages in preparation for the deployment. Each stage has its own requirements, typically automated using scripts or a workflow that performs these actions without human intervention.
A workflow can automate service deployment, testing and verification processes, and rollbacks as needed. When progressing towards production deployment, advanced pipelines use a progressive delivery strategy, such as blue/green or canary deployments, that deploys the application to its users gradually while reducing risk. These strategies help ensure a reliable and successful deployment.
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