Continuous Delivery vs. Continuous Deployment

In this article, we understand the difference and relation between the frequently misused terms Continuous Delivery and Continuous Deployment in the DevOps landscape.

Continuous Delivery vs. Continuous Deployment

Introduction to DevOps

DevOps is a blend of practices that combines Software Development and IT Operations that has come to exist to reduce silos (repository of data/code that's controlled by one department and isolated from the rest of an organization) between developers and operations teams, resulting in higher delivery speed. In addition, it is a method that streamlines the product development process by giving more importance to effective communication, integration, and better association among teams for delivering quality products at incredible velocity.

In the words of Patrick Debois, the Godfather of DevOps, "it is a movement of people who think it's time for a change in the IT Industry - time to stop wasting money, time to start delivering great software, and building systems that scale and last."

When DevOps is a highly valued philosophy, its implementation and the whole process can be simplified with an effective DevOps toolchain. The DevOps toolchain assists businesses to achieve continuous integration and continuous delivery by maintaining a healthy software development pipeline. To have an effective toolchain, developers need to use tools for each of the following;

  • Planning and collaboration
  • Source control tools
  • Tools to track the issues
  • Continuous integration
  • Configuration management tools
  • Monitoring tools
  • Testing tools
  • Deployment

Before going further and deep diving into toolchains, let’s understand the most popular DevOps practices.

With DevOps comes CI/CD/CD, which are the most used techniques to simplify the software development process, increasing the deployment speed with the quality intact. CI (Continuous Integration) and CD (Continuous Delivery and Continuous Deployment) build, test, and deploy codes emphasizing changes and automation. Today, in this article, we will understand the difference and relation between the frequently added terms Continuous Delivery and Continuous Deployment.

What is Continuous Delivery?

Before getting to the nitty-gritty of Continuous Delivery and Continuous Deployment, it's important to understand the fundamental difference between the two.

Continuous Delivery is a partly automated process where developers have to manually deploy the final version of the software, whereas Continuous Deployment is a completely automated.

As the above image states, Continuous Delivery involves manual efforts contrary to continuous deployment. It basically includes the process where developers continuously receive user feedback and simultaneously work on the alterations. This process consists of integration and testing, leaving the deployment to manual efforts.

After verification, the software is sent to the production environment for application acceptance testing. Post that comes the human actions that help improve software quality. The manual job is to verify the altered codes and review them before orchestrating their deployment. Continuous Delivery is the automated tool that pushes the codes that have completed the CI cycle into an automated environment for testing and further deployment.

What is Continuous Deployment?

Continuous deployment or an extension of continuous integration reduces the time between writing new codes and using them in production. It is a highly automated process that reduces the need for human interaction in its deployment process. The scripts take over most of the work that used to be done by humans, previously involving the physical deployment of codes. If continuous deployment is implemented in any DevOps organization, it converts the whole CI/CD/CD chain to be automated, removing the manual efforts of deploying the codes in the final stage.

The significant difference comes in the last phase, where the code passes the testing and immediately moves to the production phase. This helps businesses to enjoy the benefits of multiple deployments in a single day. However, deployments would still need a final human sign-off and how this workflow is managed on your DevOps platform is what matters in scaling your deployments. Continuous deployment can be surely the first preference for large organizations or big eCommerce platforms where time is money.

A few of the most commonly used Tools in CI/CD are with:

  • Jenkins
  • Travis CI
  • Bamboo
  • TeamCity
  • Azure DevOps
  • GoCD
  • Circle CI
  • Gitlab

The correlation and difference:

  • Continuous Delivery is a partly automated process, whereas Continuous Deployment is completely automated.
  • In short, Continuous Deployment is the ability to get software deployed in any environment, at any time. On the other hand, continuous Delivery is the capability to deploy this software to any particular environment at any given time.

E.g., Large enterprises that implement plenty of changes every day, launch various features as per user feedback, or update the portal as per the market trends and quickly put them into production. Therefore, they rely on Continuous Deployment, where all the changes developers make are deployed immediately on their production servers.

  • In Continuous Delivery, though the codes are always ready, the QA team tests each feature and then manually brings it to production. This makes sure about the quality of the product. On the contrary, in Continuous deployment, every change made is supposed to go through the pipeline, and if it passes the testing phase, it automatically goes to production. Now, the quality of the final product delivered depends on the testing suite as it is an automated deployment.

Benefits of Continuous Delivery

  • Continuous Delivery is a combination of continuous integration + the automated release of software  + manual deployment to the production
  • It makes your release processes more efficient and repeatable as possible.
  • The automated workflow until the deployment phase helps accelerate the process and boost the ROI.

Benefits of Continuous Deployment

  • Continuous deployment is Continuous integration  + continuous delivery and automated deployment to the production
  • It helps get faster feedback from the end-users as each new feature is released continuously. Thus, it aids in knowing the return on investment faster with each feature launch.
  • Automation reduces the time to take the code from developers to the end-users and increases code accuracy.

Move Fast with Stable Infrastructure

Thinking about implementing changes on a small scale, it always seems easy to manage it manually by going to each machine and pushing the codes to all. But in the same way, if you have multiple services and multiple themes with various releases, it no longer remains an easy job, and you need automation there. In other words, things get complicated when you scale.

Let's take the example of Facebook here, which has thousands of services running on uncountable machines. For a large company like Facebook with multiple users and devices, it is practically impossible for humans to test and deploy codes efficiently, and thus, automation makes a big difference.

Though FB does not push out all the changes immediately to the customers, its code can be released twice daily, related to bug fixing or internal code updates. And every week, the new production code is released. So, looking at the need of the time, Facebook has moved its mantra for developers from 'Move Fast and Break Things' to 'Move Fast with Stable Infra.'

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