What is a good usecase for using Continuous Integration & Continuous Deployment?

Question

I went through several available resources for Continuous Integration (& continuous delivery and deployment) like :

• https://www.atlassian.com/continuous-delivery/principles/continuous-integration-vs-delivery-vs-deployment
• https://www.atlassian.com/continuous-delivery/continuous-integration/how-to-get-to-continuous-integration
• Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

My question is

• when should I used continuous integration
• when should I use continuous Deployment

Answer 1

Let's try to use a really simplified and not necessarily correct real-world example:

I'm working for a company that develops Android apps. Currently we have to work on an app which is just a rather small project so just me and one other collegue work on the app.

Since we are top-notch developers we are of course writing tests and only want our code to reach the develop branch when the app actually compiles and all our tests are green.

To automate this recurring task we use an automation/continuous server like Jenkins (or something else like Bamboo) and create a workflow which builds our project's code and runs our tests whenever we try to commit any code to the develop branch. Only if it builds successfully and all tests are green will our code be integrated into the develop branch.

--> We are using Continuous Integration, yay!

Now, after some months have passed, we decide that our app is ready to be released to the users of the Play Store.

We take the code of our current (and hopefully thoroughly tested) version of our app from the develop branch and copy it to a new branch named release.

The release branch is used in a second Jenkins workflow which for now does the same as our first one: It builds the code from this branch and runs the tests against it.

Then we need to add another step to the new Jenkins workflow. When our app's code was successfully build and all tests are green, we want the app to be automatically deployed/uploaded to the Play Store so the users can download and install it on their phones.

--> We are using Continuous Deployment, yay!

Answer 2

As you have through the link mentioned in question so I am assuming that you are aware of what is continuous integration and deployment.

Simply when you need to integrate test (or something additional) before deploying code and want to automate this task you can use an continuous server like Jenkins/circleCI AKA continuous integration tools.

Now If you want that your deployment to server (production ) should be automatically triggered without manual promoting to production then you should go by continuous deployment.