Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

Continuous integration, continuous delivery, and continuous deployment are foundational in today’s agile engineering ecosystem. However, many times they are used interchangeably and often incorrectly. Let’s remove the confusion and settle the differences between continuous integration, continuous delivery, and continuous deployment.

What is Continuous Integration?

Continuous integration happens when developers regularly integrate their code into a shared main branch to reduce conflicts when they merge their code later on. This approach helps to discover conflicts sooner and reduces the chances of larger and more complex conflicts found when waiting until later to merge. 

A fundamental part of continuous integration is having your automated tests run immediately upon merging your pull request. If the automated tests pass with your changes, your code will be integrated into the main branch. If not, your pull request will be blocked, and you will have to analyze the failures. In this way, you are ensuring that your code does not break any existing functionality. Another fundamental component of continuous integration is to push with changes of smaller individual scope. It is a commonly-known best practice that pull requests should not have a lot of content to parse through because if a test fails, it’s essential to identify where the bug is in the code quickly.

What is Continuous Delivery?

If continuous integration happens when you continuously merge your code to master to avoid late discovery of conflicts with fellow teammates’ code, what is continuous delivery? Continuous delivery is when you take that shared branch (master/main) and can push it to production safely and quickly. The key distinctions are that it should be fast and automated to get quick feedback and eliminate the chances of human error. We want to make the process of pushing to production “boring,” so we can focus our attention on adding value, not triaging the deployment. If there is a critical bug in production, you want to get the fix out as fast as possible. Remember that you need continuous integration to do continuous delivery.

What is Continuous Deployment?

Teams that choose to push successful builds to production automatically are practicing continuous deployment, and every change that was not blocked by the automated tests gets deployed to production. The changes that cause failures in the tests are not merged with the main branch and are then flagged for attention. Continuous deployment requires the most evolved level of automated testing and proactive monitoring to detect unforeseen issues quickly.

Make it Easier with Feature Flags

Feature flags allow software development teams to separate code deployment from feature release. This will enable engineers to continually merge their new feature code with the main branch and deploy it to production without having their end-users be exposed to the feature yet. Feature flags enable continuous delivery by allowing the teams to release the feature to their end-users when it is ready and have a kill switch if something goes wrong. This also adds a safety net to the continuous deployment process because if something goes wrong and there is a bug in production, you can quickly turn that feature off with the click of a button. 

CI, CD, and CD

Innovative, agile teams will continuously be implementing new practices and new processes. Adding continuous integration, continuous delivery, and continuous deployment will make your release cycle smoother, faster, and more well-managed. Feature flag management systems make it easier to release features by separating code deployment and feature release. Not only does this simplify the testing process, but it adds a layer of risk mitigation in case a bug was released. It is also recommended to use a feature flag management system for continuous delivery as companies and teams scale because you can quickly turn off a feature if it doesn’t work in production. 

Learn More About Continuous Deployment and Feature Flags

Continuous integration, continuous delivery, and continuous deployment can be confusing topics. When implemented correctly and in sync with one another, they can provide a seamless process that will only benefit your release cycle. To find out more about CI, CD, and feature flags, check out the following posts.

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