Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

Question

What\'s the difference between these three terms? My university provides the following definitions:

Continuous Integration basically just means that

Answer 1

lets keep it short :

CI: A software development practice where members of a team integrate their work at least daily. Each integration is verified by automated build (include tests)to detect error as quick as possible. CD: CD Builds on CI, where you build software in such a way that the software can be released to production at any time.

Answer 2

Continuous Integration: The practice of merging the development work with the main branch constantly so that the code has been tested as often as possible to catch issues early.

Continuous Delivery: Continuous delivery of code to an environment once the code is ready to ship. This could be staging or production. The idea is the product is delivered to a user base, which can be QA's or customers for review and inspection.

Unit test during the Continuous Integration phase can not catch all the bugs and business logic, particularly design issues that is why we need QA, or staging environment for testing.

Continuous Deployment: The deployment or release of code as soon as it's ready. Continuous Deployment requires Continuous Integration and Continuous Delivery otherwise the code quality won't be guarantee in a release.

Continuous Deployment ~~ Continuous Integration + Continuous Delivery

Answer 3

Source: https://thenucleargeeks.com/2020/01/21/continuous-integration-vs-continuous-delivery-vs-continuous-deployment/

What is Continuous Integration Continuous Integration is a process or a development practice of automated build and automated test i.e. A developer is required to commit his code multiple times into a shared repository where each integration is verified by automated build and test.

If the build fails/success it is notified to a developer and then he can take relevant actions.

What is Continuous Delivery Continuous Delivery is the practise where we keep our code deployable at any point which has passed all the test and has all the required configuration to push the code to production but hasn’t been deployed yet.

What is Continuous Deployment With the help of CI we have created s build for our application and is ready to push to production. In this step our build is ready and with CD we can deploy our application directly to QA environment and if everything goes well we can deploy the same build to production.

So basically, Continuous deployment is one step further than continuous delivery. With this practice, every change which passes all stages of your production pipeline is released to your customers.

Continuous Deployment is a combination of Configuration Management and Containerization.

Configuration Management: CM is all about maintaining the configuration of server which will be compatible to application requirement.

Containerization: Containerization is a set of tolls which will maintain consistency across the environment.

Img source: https://www.atlassian.com/

Answer 4

I think amazon definition is straight and simple to understand.

"Continuous delivery is a software development methodology where the release process is automated. Every software change is automatically built, tested, and deployed to production. Before the final push to production, a person, an automated test, or a business rule decides when the final push should occur. Although every successful software change can be immediately released to production with continuous delivery, not all changes need to be released right away.

Continuous integration is a software development practice where members of a team use a version control system and integrate their work frequently to the same location, such as a master branch. Each change is built and verified by tests and other verifications in order to detect any integration errors as quickly as possible. Continuous integration is focused on automatically building and testing code, as compared to continuous delivery, which automates the entire software release process up to production."

Please check out http://docs.aws.amazon.com/codepipeline/latest/userguide/concepts.html

Answer 5

Neither the question nor the answers really fit my simple way of thinking about it. I'm a consultant and have synchronized these definitions with a number of Dev teams and DevOps people, but am curious about how it matches with the industry at large:

Basically I think of the agile practice of continuous delivery like a continuum:

Not continuous (everything manual) 0% ----> 100% Continuous Delivery of Value (everything automated)

Steps towards continuous delivery:

Zero. Nothing is automated when devs check in code... You're lucky if they have compiled, run, or performed any testing prior to check-in.

1. Continuous Build: automated build on every check-in, which is the first step, but does nothing to prove functional integration of new code.

2. Continuous Integration (CI): automated build and execution of at least unit tests to prove integration of new code with existing code, but preferably integration tests (end-to-end).

3. Continuous Deployment (CD): automated deployment when code passes CI at least into a test environment, preferably into higher environments when quality is proven either via CI or by marking a lower environment as PASSED after manual testing. I.E., testing may be manual in some cases, but promoting to next environment is automatic.

4. Continuous Delivery: automated publication and release of the system into production. This is CD into production plus any other configuration changes like setup for A/B testing, notification to users of new features, notifying support of new version and change notes, etc.

EDIT: I would like to point out that there's a difference between the concept of "continuous delivery" as referenced in the first principle of the Agile Manifesto (http://agilemanifesto.org/principles.html) and the practice of Continuous Delivery, as seems to be referenced by the context of the question. The principle of continuous delivery is that of striving to reduce the Inventory waste as described in Lean thinking (http://www.miconleansixsigma.com/8-wastes.html). The practice of Continuous Delivery (CD) by agile teams has emerged in the many years since the Agile Manifesto was written in 2001. This agile practice directly addresses the principle, although they are different things and apparently easily confused.

Answer 6

Continuous Integration

• Automated(building of check ins + unit test)

Continuous Delivery

• Continuous Integration
• Automated(deployment to test environment + load testing + integration test)
• Manual(deployment to production)

Continuous Deployment

• Continuous Delivery but automated(deployment to production)

CI/CD is a journey. Not a destination.

These stages are suggestions. You can adapt the stages based on your business need. Some stages can be repeated for multiple types of testing, security, and performance. Depending on the complexity of your project and the structure of your teams, some stages can be repeated several times at different levels. For example, the end product of one team can become a dependency in the project of the next team. This means that the first team’s end product is subsequently staged as an artifact in the next team’s project.

Footnote :

Practicing Continuous Integration and Continuous Delivery on AWS