CI/CD is the combined practices of continuous integration (CI) with continuous delivery or continuous deployment (CD). The purpose of CI/CD is to allow development teams to deliver code changes more frequently and reliably.
The CI in CI/CD stands for continuous integration. Continuous integration means that developers frequently merge their code changes to a shared repository. It’s an automated process that allows multiple developers to contribute software components to the same project without integration conflicts. CI involves automated testing whenever a software change is integrated into the repository.
CD can stand for either continuous delivery or continuous deployment. Both involve taking the code continuously integrated and getting it able to deploy to an environment either QA or production. Continuous deployment takes the process one step further and performs the actual deployment to an environment.
When large pieces of a code base change at a time it puts an application's quality at higher risk. This is because there is more likely a chance that something will break the larger the change - and troubleshooting is harder the larger the change. Agile organizations frequently integrate their code and perform automated tests to reduce the cost of introduction, identifying root causes, and fixing bugs.
Automation is key to CI. There is no way someone could keep up manually at the speed needed for continuous integration to be successful. Developers need to integrate frequently and need feedback as soon as possible.
Continuous delivery and continuous deployment have similar goals, as they use automation to reduce the time, effort, and risk involved in shipping a release. Continuous delivery is quick and efficient. Every build is automatically tested in each environment, and if it passes, the code can be manually deployed with a single click. The preparation is automated, but the push to production is often initiated by the operations team.
With continuous deployment, in which the release to production is fully automated, you relinquish some control. At the same time, you gain additional advantages. You can develop at an even higher velocity than the already-fast continuous delivery, since you don’t need to pause development for releases, and your customers will appreciate the steady stream of improvements.
The benefits of CI/CD are numerous, but implementing the process can present challenges. First, while continuous integration and continuous delivery/deployment are related, they are distinct parts of the CI/CD pipeline. When organizations don’t understand the difference, they can end up implementing CI alone and calling it CI/CD. For proper CI/CD, your continuous code integration—likely done with a CI-specific tool—needs to feed into automated processes for testing and deployment.
CI/CD involves many players. As with all DevOps methods, it requires strong collaboration between development, QA, and operations teams (another challenge in many organizations). Teams often struggle with the fact that dev, QA, and ops are pursuing seemingly contradictory goals. Developers want to put out new code quickly and have creative freedom. QA wants to test the code to minimize releases with any bugs. Operations wants the code to be released and run in a way that is safe, accurate, and controlled. Luckily, a good CI/CD setup facilitates this type of cooperation. Developers stay productive and efficient because they don’t have to spend too much time debugging, and operations can rest assured that code is well prepared for release. The handoff from one team to another is automated and less painful. For best results, it’s important to make sure everyone is clear on who owns which part of the pipeline as well as the overall process.
An additional challenge is knowing how to implement a new CI/CD process. Automation is essential, as frequent, repetitive processes can delay the CI/CD pipeline and can be highly prone to errors if completed manually. It’s recommended to start with automation within a small team to demonstrate success to the leadership team for a broader automation effort.
Security is a challenge for every organization these days, and security measures are too often an afterthought in the DevOps process when they should be integrated as early in the software development lifecycle (SDLC) as possible. That way security risks are detected early, when they are less costly to fix.
CI/CD facilitates a faster time to market. Automation streamlines parts of the process, while quicker error detection leads to less time putting out fires. Customer satisfaction can increase as well when you’re providing more regular updates and a positive user experience.
The incremental changes and automated integration of CI can improve the quality of code in each update. Reducing the instances of faulty code getting pushed to production has countless positive business impacts.
When speed and accuracy increase, costs drop. Your CI server can run hundreds of tests within seconds, drastically cutting down on testing costs. You undoubtedly have competitors using CI/CD, and if you’re sticking with traditional models, you’ll be left behind.
Transitioning to CI/CD is best done in phases. This allows developers to learn and adapt to process changes and ensures that the new process will be fully tested before its introduction to production systems.
To set yourself up for success with CI/CD, start with these steps:
Now that you’ve built a solid foundation on which to start your full CI/CD migration, you can move to the next phase:
You now have a functional CI/CD process. Much of the automation will be executed by software, but it’s essential that your developers have proper training on both software and processes.