CI or Continuous Integration is the automatic integration of code changes from multiple developers into a single codebase. It is a software development practice where the developers commit their work frequently into the central code repository. Then there are automated tools that build the newly committed code and do a code review.
The key goals of Continuous Integration are to find and address bugs quicker, make the process of integrating code across a team of developers easier, improve software quality, and reduce the time it takes to release new feature updates. Some popular CI tools are Jenkins, TeamCity, and Bamboo.
Imagine you have a group of developers working on a software project, but they work on their own without regularly sharing their work with others. They only combine their changes into the main project once they finish their work. This leads to a few problems:
- Combining everyone's work becomes really hard because it's all done at once, and it often results in conflicts, where different pieces of code don't fit together smoothly.
- Since nobody is checking the code frequently, bugs can hide in the code for a long time, making them harder to find and fix.
- It becomes difficult to deliver updates to customers quickly because a lot of time is spent dealing with merging and fixing problems.
Instead of working in isolation, developers regularly share their work with a common place (a shared repository) using tools like Git. This common place is like a big box where everyone puts their work. Whenever someone commits their code, a special computer program (CI pipeline) automatically checks their work. It does a few important things:
- It makes sure the code can be turned into a working program.
- It runs tests to make sure the code doesn't break anything that was working before.
- It can even use tools to give feedback on the quality of the code.
Continuous Integration is a way for developers to work together smoothly, catch mistakes early, and deliver software updates faster and with fewer bugs. It's like having a robot assistant that helps ensure the code is always in good shape.
Continuous Delivery (CD) is like a well-organized system that helps software developers release new updates to their customers quickly and without errors. It works closely with Continuous Integration (CI) and focuses on making sure the software is ready for release.
Here's how it works:
- CD comes into play after Continuous Integration has already checked the code for basic issues and merged it together.
- It sets up a staging area, which is like a test environment that's very similar to the real production environment where your software will run.
- In this staging area, CD runs various tests. These tests include integration tests (to make sure different parts of the software work together) and regression tests (to make sure new changes don't break things that were working before).
- CD automates the process of getting your software ready for release. It's like having a robot do all the repetitive and time-consuming work.
- The goal of CD is to always keep your software in a state where it's ready to be released. This means you can deploy it to the live production environment whenever you want.
- CD gives control to the developer or project lead to decide when to actually release the software to customers. It's not automatic, so you can choose the right moment.
- There are tools available to help with Continuous Delivery, like AWS CodeDeploy, Jenkins, and GitLab. These tools make the process smoother and more efficient.
Continuous Delivery is like having a smart system that checks your software, makes sure it works properly, and gets it ready for release whenever you say the word. It's all about delivering high-quality software to your customers without the hassle of manual work and with the flexibility to release it when it makes sense.
Continuous Delivery means the code is automatically prepared for release and tested, but a human decides when to actually release it to production.
Continuous Deployment means the code is not only automatically prepared and tested but is also automatically released to the production environment without anyone having to say, "Release it now."
Think of Continuous Delivery as having a stop sign that requires a human to decide when to go, while Continuous Deployment is like a traffic light that automatically turns green when it's safe to proceed.