Continuous integration and continuous deployment: a quick introduction

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A few months ago, we explained how to apply continuous integration in your Rails project by using GitHub actions. Here we’ll discuss the whole CI/CD pipeline for Rails. We all know how key this pipeline is to releasing new software with high-quality code, so let’s go deep into it. 

In this new article, we’ll define continuous deployment and integration, and their differences from continuous delivery. Plus, we’ll check out why they’re so important for your development process by exploring the advantages and costs they have, and which one should be on the top of your list to begin with. Ready to know more about Rails' continuous deployment and integration?


What are continuous integration and deployment about?

Let’s start by quickly defining what continuous integration and continuous deployment are. When we talk about continuous integration, we talk about an approach that enables automated testing of each codebase change. It can also be thought of as a process that unlocks automated integration of the code into your product. This helps you to identify and rectify errors quickly and early.

How does it work? You have a central repository where your code is integrated to perform testing and building. Then you just let continuous integration do the rest: it will automatically run tests that will give you feedback about your code.  

Continuous deployment, on the other side, is often confused with continuous delivery. Let’s discuss the first one. Continuous deployment is the process that allows you to release your product faster because its approach is mainly about developing software in a short cycle. Relying on it, developers can deploy the code straight to the production stage when it’s developed. It tweaks and takes continuous delivery to the next level because there’s no manual deployment at the end. You just have to write a script that pushes anything that gets to the master branch right into the production environment. To apply continuous deployment in the right way, you’ll need good testing. Note that extra automated testing is added and needed to make sure that no bad code arrives at the production stage.

For continuous deployment in Rails, you can use different products and open-source libraries. For instance, if you want to maintain code quality, you can go with Cane and Rubocop, and if you want to monitor performance metrics you can choose Bugsnare, New Relic, or PagerDuty.

Although we talked briefly about continuous delivery, let’s check it out to make the difference between this and continuous deployment clearer. Continuous delivery is more about a logical evolution of continuous integration. Its focus is on releasing new changes for clients properly and the last decision will always be on you. Why? Because in continuous delivery, developed code is delivered constantly until you think it’s good to go. In this case, business logic tests are used, and you can verify software updates.


Why are they key for your work process?

Yes, continuous integration requires writing automated tests for each new feature or improvement, and a continuous integration server ready to monitor the main repository and run automated tests. Plus, you’ll need to merge the changes you do at least once daily. But continuous integration brings you tons of advantages that make these requirements an easy job.

Among those advantages you can find:

  • Early feedback to ensure that your software has better quality. You can even get immediate feedback when an error arises.
  • Fast iteration.
  • Cost reduction in terms of testing, because the continuous integration server is empowered to run hundreds of tests in seconds.
  • Code stability.
  • Allowing developers to create independently and parallel new features.

On the other hand, continuous deployment has its costs too. For instance, you’ll need a strong testing culture because it will mainly shape the quality of the products you release. Another example is that your documentation process will need to follow the rhythm of deployments. But, just like what happens with continuous integration, the advantages make these costs smaller.

Some of the benefits that make continuous deployment key for your development environment:

  • Fast feedback, so there’s no waste of time between you merging in your changes and those changes running live in production.
  • Less risky releases due to faster response in case you need to fix any issue.
  • More predictability because automated deployment ensures that you run the same script every time. Plus, automation lets you get rid of repetitive tasks.
  • Easy scalation if you want, for example, to scale from a single Rails app to the whole company IT portfolio.
  • Enhanced visibility because it empowers you to have a single view of all your environments and applications.


Which one should you embrace first in Rails?

If your project is new and hasn’t gotten in touch with your users yet, you can try automating your deployments and releasing a version to production. Once you’re done with that, it'd be good to train the testing culture in your team and strengthen the quality of your code, so you make sure that it meets great quality standards while you’re building your app. If you do this, when users start using your product, you’ll have a smooth continuous deployment process ready to test all the changes you need before they’re automatically released to production.

In case your scenario is different, and your product is already in touch with users, then you should begin with continuous integration instead. You have to implement basic unit tests and automate them and automate your deployments as fast as you can. The goal is that you can automate the deployments to your staging environments, so you can just keep an eye on making your tests better, instead of having to stop working to coordinate a release. 

Continuous integration and continuous deployment are just a part of how you can seize Rails and create better apps. And if you found it useful and you want to learn more about Rails and its advantages for your project, have a look at our blog.

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Santiago Bertinat
November 24, 2022

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