What’s the Difference Between Continuous Integration, Continuous Deployment, and Continuous Delivery?

Knowing the concepts of continuous integration, deployment, and delivery makes a difference

In this article, we're going to explore the differences between continuous integration, continuous deployment, and continuous delivery. And why, although not might seem like a bit of a mind-melt, they are the same or at the very least one branch of a very complex tree — one that guides most software's lifecycle. Let's dive right in and get a handle on what each of these methodologies is and how they complement one another. 

What is continuous integration?

Continuous integration is a process of merging all of the code changes made by developers into one or more shared repositories. The main goal of continuous integration is to ensure that any change to the code base will not disrupt other parts of the system.

Before, traditional testing was a bit quarantine — departments, teams, and freelancers were isolated from one another. At most, they had a weekly or biweekly meeting. Everyone was sort of doing their own thing, working on a very rough draft, and then butting heads — trying to make everything mesh together. 

Thanks to continuous integration that is no longer the case. Today, codes, fixes, improvements, and updates are shared in a loop and constantly. 

Benefits of continuous integration

Most developers have probably heard about continuous integration – CI – by now. But for those who haven't, it is a development practice that requires developers to integrate code into a shared repository several times a day — like the name states, "continuously."

The benefits of CI are numerous:

• CI makes sure that the codebase is always in an acceptable state.
• CI gives developers peace of mind knowing that their work will not be lost due to errors.
• CI allows teams to keep track of changes across the system.
• CI allows members to integrate changes from other departments into their projects.

What is continuous deployment?

Continuous deployment is a software engineering practice in which code changes are immediately deployed to the production environment. It is a way of incorporating software updates, into production, rapidly.

The goal of continuous deployment is to reduce the amount of time that elapses between when code changes are made and when they reach users. It also reduces the risk that bugs will be introduced into production environments.

Benefits of continuous deployment

Continuous deployment is a software engineering practice in which code is automatically deployed to production after passing all the necessary tests.

It is a way to release software updates without going through the lengthy process of a new release.

It can be used when there are small changes to an application, or when it has been weeks or months since the last update. 

Continuous deployment has many benefits including:

• faster time-to-market.
• reduced risk when deploying updates.
• Better quality products. 
• Increased customer satisfaction.

What is continuous delivery?

Continuous delivery is a software development practice where teams produce and ship an application to the end users after each change. This means that any change, no matter how small, is immediately deployed to the end-user.

Companies use continuous delivery to improve customer experience and increase their revenue. It also helps them reduce costs because it enables them to deliver updates faster than with traditional release cycles.

Sounds a bit like continuous deployment, right?

Where it differs is that CD or continuous deployment "deploys" the changes into the production environment. The production incorporates those changes and later passes them off, all ready and willing to go, to delivery.

Benefits of continuous delivery

One of the main benefits is that it delivers products as soon as they are ready. It promotes rapid feedback, frequent deployment, and fast recovery from mistakes.

The benefits of continuous delivery are:

• Deploying features faster
• Feedback on new features
• Increased visibility on the business impact of changes
• Reduced risk of errors

A long hard look at continuous integration, continuous deployment, and continuous delivery

CI, CD, and CDY — are all parts of the same model. They are all key parts of having a competent, efficient, and highly adaptable product lifecycle. 

• Continuous integration makes sure that your teams are in-synch, that everything, no matter how small is being shared and saved constantly, Team members can view each other's work, incorporate codes from their peers and better build their system — knowing that everything is safeguarded.
• Continuous deployment then takes these changes, these new tweaks, and incorporates them into a new version of the software. It tests it, it makes sure production values are being kept, and it makes certain quality issues and metrics are upheld.
• Continuous delivery then takes the product, that version of the product, and instantly sends it out to end-users. It doesn't wait for scheduled launch dates.

The best way to explain the whole process is through a real-life example — Apple's IOS updates.

Apple constantly ships out updates to its operating system. They have a huge launch in September with the new general IOS. Then they have smaller, scheduled launches throughout the year. BUT between these updates, they make tiny little changes to the system. Changes that don't merit a press release, but changes that incrementally mean a lot.

If you look at what version of the IOS you might have installed, it's divided into 3 numerical values. For example 15.2.1. The first number labels the year, update version, this is what is released in September — in this case, the 15. The second number dictates the scheduled update — in this case, the 2. And the final number is the small, not worth making a big show out of, continuous delivery update. That last number is the result of continuous integration, continuous deployment, and continuous delivery methodology. 

Apple's update might have been something as innocuous as a new font, a new security update, or fixing a battery issue.  

How to incorporate Continuous Integration, Continuous Delivery, or Continuous Deployment into your IT processes.

And an overhaul of your system is complex — not only because it needs a massive technological platform and investment, but because you have to change your worker's mindset. Start to create a value system within your company that takes all these methods into account. It's important to seek out help and have a consultant at hand that can help you better understand and approach your goals.