Continuous Integration (CI), Continuous Delivery (CD), and Continuous Deployment (CD) are three important practices in software development that aim to improve the speed and quality of software delivery.
This article will cover:
- What is Continuous Integration (CI)?
- What is Continuous delivery (CD)?
- What is Continuous Deployment (CD)?
- Stages of CI/CD
- Best practices for CI/CD
- Benefits of Continuous Integration
- Benefits of Continuous Delivery
- Benefits of Continuous Deployment
- Common tools for CI/CD
Continuous Integration (CI) is a process where team members push changes they make to the software to a central repository. Before they merge those changes, they run a series of tests to find out whether there are errors.
When a team member makes updates to the software and submits it for merging, it goes through a review by the team lead. The continuous integration tools run automated tests to cross-check the update before merging it.
Continuous Delivery is a process where you set changes in a staging environment for further testing awaiting deployment. It continues where continuous integration stops.
Continuous delivery ensures that the software update you send to the production environment is ready by conducting further tests and validating the release process. To make deployments, you will need to write a deployment script or click a button.
You could choose when you want to deploy your changes in this case.
Continuous deployment is the next automated process that occurs after continuous integration.
When you use continuous deployment, it means automatic deployment after integration. So after your changes pass through tests and you merge them, it gets deployed immediately.
Continuous delivery differs from continuous deployment in the sense that companies could choose to apply continuous delivery or continuous deployment.
In continuous delivery, deployment is manual. You could do that by pressing a button, but in continuous integration, deployment happens immediately after continuous integration without further delay.
Code commit: This is the first step. Team members commit their changes to a shared repository, triggering the pipeline to begin.
Build: The pipeline generates a build of the software, including the changes made to it.
Test: The next step is to run a series of tests on the build to find out if there are errors.
Review: After running the tests, a review takes place by the team lead and other stakeholders to view the changes made to the application and how these changes look. CI usually generates a preview site so this review can take place.
Merge: After the review, if the changes pass the checks, merging takes place into the repository.
Continuous delivery takes a step further by staging the updates for deployments.
Release: After team members have added all the expected changes needed, Then the pipeline runs further tests on it before making a release and awaiting deployment.
Deployment: This is when they deploy the release to production and end-users can operate the new deployment. Most times, the team could send the deployed software to a specific set of users for further review. Deployment is manual.
Operate: In this stage, they would operate the application and also inspect all the previous operations for backward compatibility. Just to ensure that it works properly.
Monitor: This is the last stage; it involves monitoring the site to inspect how the application runs on every device and watch out for user complaints.
- Code commit like in previous processes.
- Build, test, and review
- After merging takes place,
- Release - Generate a release by staging it in the test environment. Deployment is automatic in this process; it happens immediately after the release stage.
- Operate and monitor - Like in continuous delivery, this is the next step that follows suit where users operate the application and you monitor it to notice if there is any harm, in which case you can recall the changes.
Here are some practices you could use to apply these processes in your organisation.
Have a documented plan: Set up documentation that details the steps team members are to follow in applying any of the processes.
Versioning: Version control is essential for managing code changes and ensuring that all team members are working on the latest version of the code. There are many version control options, like Git, SVN, Mercurial, and so on. You could use any of them to track changes and team collaboration.
Automation: Automation is an important step in CI/CD. Ensure you apply automation by using tools for CI/CD. With automation, you can run tests on changes, generate previews of changes to share with team members and make fast deploys.
Communication and collaboration: Break down tasks among members to promote communication and knowledge sharing. DevOps promotes participation across all fields, so set up workflows in a way that everyone gets to contribute and partake in the processes.
Intermittent deployments: Make deployments as soon as possible. This would help you monitor the minor updates you pushed to production to avoid complex bugs. Some organisations make 50 deployments daily, and some make 100 deployments daily. That way, they can roll back updates if something goes wrong.
Monitoring: After you make deployments, monitor your updates and user engagements to observe if the updates are great for the software. Use monitoring tools to monitor and measure the performance of your application and infrastructure.
By implementing these best practices, you can build a reliable and efficient software delivery process for your application.
Some benefits of applying continuous integration are,
Continuous integration ensures developers can code, build, and commit code within a short time frame.
With tests in place to review the code for bugs. This way, team members can have their commits done and move on to another process.
CI tools automate integration processes, which means members can focus on producing code while CI tests their input before merging it into the source repository.
CI runs a series of tests to ensure there are no errors. This improves the quality of the product. With that, teams could also add user feedback to improve the software. When developers push their changes, if there are any errors, they could easily work on them before making another update.
Also, continuous integration is a consistent routine that ensures that the software quality is always of a high standard.
Continuous integration runs repetitive tests on updates before merging them. This reduces the possibility of deploying buggy software.
Also, when developers make errors in their commits, they would have to review them and correct the mistakes. This improves the chances of making bug-free updates in production.
CI fosters communication among teams, as teams would need to work together in building the software.
With a CI pipeline in place, product managers can set product fixes, and developers can build and share their work across the team. Sometimes, other team members would need to contribute their own input to the product before pushing it to the repository, promoting collaboration.
With a CI pipeline in place, developers can make frequent code commits in a day. When they fix a specific issue and make a commit, the CI pipeline can take care of the testing while the developer can work on another issue, increasing their work rate.
In continuous delivery, some benefits you could gain from it include,
Continuous delivery eliminates the long, stressful manual release process. With automation, developers can make releases easily until they are ready for deployment.
CD tools run checks to ensure the new releases are accurate and highlight possible errors.
Continuous Delivery uses automation in its release process, which makes the process secure and more efficient. Developers could focus on coding without worrying about the product release process. Which reduces their workload and makes the complete process faster.
With the CD pipeline, developers can meet deadlines and make as many updates as possible.
Knowing they can make updates after release, they can deploy and make more improvements for delivery.
When there is a trend and companies need to adjust to keep getting their checks.
Developers could make updates, and the CD pipeline would release them and make them ready for deployment.
With CD, developers are faster and better able to meet urgent market demands.
It improves developer productivity, making it possible for them to achieve so much within a short time frame.
Some benefits of continuous deployment are
Continuous Deployment ensures the safe and smooth deployment of code. With just a button click, you can deploy your release. Just like the other processes, continuous deployment uses automation to carry out this process, removing all forms of manual work.
Continuous deployment improves developer productivity as they have less to worry about. Instead of following through with a manual process of deployment, they can use CDs continuously to deploy code whenever they want and meet their goals.
Continuous Deployment tools can integrate with continuous integration tools. There are tools that perform both roles, setting up workflows that run across the entire process. After deployment, monitoring takes place in order to inspect for changes, which could be positive or negative.
Continuous deployment involves monitoring the software after deployment to find out the state of the product or if users are unhappy with the launch. The next process that takes place would depend on the monitoring. If, from monitoring, the software is bad, they could roll back the updates. If it needs improvements, then developers would start working on a new feature.
Jenkins is a free, open-source and popular continuous integration tool used to build and test applications. It has multiple plugins, which make it customizable and allow for continuous deployment too. It has customised packages for Windows, macOS, and Linux operating systems.
Travis CI is another popular continuous integration tool on the market. It has a free plan and paid plans too. It serves as a CI tool for running tests and building, and it supports a wide range of programming languages. Travis serves primarily as a continuous integration tool, but it also runs deployments of applications. It runs on major operating systems.
GitHub Actions is a CI/CD tool that works with the GitHub repository model to build, test, and deploy updates. It is customizable, as you could build your own GitHub Actions clone using their API and run and manage your application as you wish. It is available for all the plans on GitHub, including the GitHub free plan.
BitBucket Pipelines is a CI/CD tool that runs on BitBucket. It automates builds and deployments and integrates tools like Jira and Trello into your workflows. It offers free plans and paid plans. BitBucket provides a seamless experience for its users, just like GitHub does.
Semaphore doubles as a CI/CD tool. You could use it to build and test your updates and make releases. It has a seamless deployment process, and it is fast. It has support for multiple programming languages. Like Travis CI, it has paid plans and a free trial. Semaphore cuts across the entire DevOps process, as it can handle continuous integration, delivery, and deployment with no additional integration.
CI/CD improves software development and reduces the workload on engineers. Continuous delivery involves a manual process in deployment, while continuous deployment deploys automatically.
There are a set of practices you could use to apply these processes in your organisation.