CI/CD combines the practices of continuous integration (CI) and Continuous Delivery (CD) to allow DevOps teams to deliver code updates frequently, reliably, and quickly. CI/CD emphasizes automation throughout the development lifecycle (Buid, Test, Deploy). By replacing the manual efforts of traditional development, code releases can happen more frequently, and with less bugs and security vulnerabilities.
Differences Between Continuous Integration, Continuous Delivery and Continuous Deployment
What Is Continuous Integration?
Continuous integration integrates code changes into a shared repository of source code, and it usually automatically tests these changes as soon as they are committed. Continuous integration is performed as your developers write code, rather than afterward.
The primary advantage of CI over deferred integration is a significant reduction of risk. Your team always knows exactly where they are in their processes: they know what works and what doesn’t, what bugs need to be fixed and what their fellow team members are doing. You can find out things are going wrong much earlier in the software development life cycle. CI also comes with a much lower chance of code conflicts, since the work of multiple developers is regularly combined.
What Is Continuous Delivery?
Continuous delivery is an extension of continuous integration in which your team automatically deploys new code to a repository (such as GitHub). It can then be deployed to production at any time based on your needs and the needs of your clients. The added automation used by continuous delivery greatly reduces the amount of effort required to deploy code. With continuous delivery, you can respond more quickly to anything from changes in the market to security flaws.
For continuous delivery to work well, you need a highly reliable integration server and a large up-front investment in hardware. Your DevOps team will also need to be able to handle the switch from manual testing to automated testing, which is a major sticking point for many companies.
What is Continuous Deployment?
Continuous deployment is the most advanced step along the CI/CD pipeline. The primary difference between continuous deployment and continuous delivery is that continuous deployment automates the process of releasing code updates to production. For continuous deployment to work, you need to devote a lot of resources to automated tests, because it removes the manual gate before code deployment.
As with continuous delivery and integration, continuous deployment comes with a high initial cost. However, you gain the benefit of near-instant user feedback and a much lower latency period between when code is first created and when it becomes live.
The CI/CD Pipeline
Changing to an environment that uses continuous integration and delivery means making fundamental changes to the way you think about your company. The first step toward making these changes is gaining an understanding of the CI/CD pipeline so that you can implement the changes your company needs.
Understanding the CI/CD Pipeline
The CI/CD pipeline is the set of processes that drive your preferred combination of continuous integration, delivery and deployment, and it forms the base of your DevOps team’s operations. In general, the head of your DevOps team is the one in charge of ensuring that the pipeline is working properly.
Components of a CI/CD Pipeline
Every CI/CD pipeline will look different based on your team’s specific needs and resources, but in general, they have four essential stages.
- Build. In this stage, you pull your source code from a repository and build its components into a binary artifact. Your chosen integrated development environment (IDE) may help your developers automate this process.
- Test. With the CI/CD pipeline, you want to employ as much continuous testing as possible. Unit testing helps to verify that new features are working as intended, and most of your testing should be this type. Regression testing makes sure that new additions to your code won’t break your existing infrastructure.
- Deliver. After your tests are done, your developers’ code should go to a staging environment. This enables you to perform A/B tests and find lingering problems, as well as letting your QA team know what they need to look at.
- Deploy. Once your build has passed all automated testing, it can be deployed in production. With continuous delivery, the build is sent to a human for manual approval, while with continuous deployment the build is deployed automatically.
Purpose of the CI/CD Pipeline
There are a lot of reasons why your development team may wish to implement a continuous integration, continuous delivery and continuous deployment pipeline. The main purpose of a CI/CD pipeline is to give your team a consistent, reliable process for releasing new code. This also has the benefit of minimizing the amount of human error that makes it into the code that gets released.
When implementing a CI/CD pipeline, consider the following best practices.
- Measure and monitor your pipeline using as many automated tests and metrics as you can.
- Preserve the same build environment for every stage of the pipeline.
- Streamline your automated testing by running the fastest tests first.
- Don’t allow your team to deploy source code without going through the pipeline.
Not all CI/CD pipelines are equal. The best ones focus on speed, accuracy and reliability, allowing your software development team to seamlessly integrate changes to your source code.
Because every development team is different, every CI/CD environment will look different as well. This has led to a huge variety of tools that can help you continuously integrate, deliver and deploy code. Some of the most used CI/CD tools are:
- Jenkins. This open-source code deployment software is free to use and suitable for even large projects. It works on Windows, Mac, Linux and Unix.
- AWS CodeDeploy. This code deployment platform is great for startups and smaller projects. It’s free to deploy code through AWS Lambda or Amazon EC2: your team pays $0.02 for every on-premises instance.
- DeployBot. This CI/CD tool is suitable for any size of business. It can deploy code from many different branches simultaneously, and it allows you to roll back releases easily.
- Octopus Deploy. Octopus is one of the most versatile cloud deployment platforms. It can easily run custom scripts and handle certificate management on even the most complex networks.