One day Mickey was taking a walk at the riverside when Minnie came running to him
Minnie – Hey Mickey, Wait for me!
Mickey – Hi Minnie, what happened?
Minnie – I need to talk to you
Mickey – Sure, tell me
Minnie – Do you know what is Continuous Integration?
Mickey – Sure I do, Minnie
Minnie – Great can you make me understand, like from scratch
Mickey – I know, the best way you understand is with a Story. Let me tell you one
Minnie – Great, let’s go to some quiet place
Mickey & Minnie went to a quiet place near the river
Mickey – Have you ever played the game LEGO
Minnie – Yeah, it was one of my favorites, I used lego blocks to create so many things, houses, cars, buildings, parks etc
Mickey – Great, so let’s imagine you and your friends play together with lego blocks and create an awesome huge house
Minnie – Wow, I can imagine
Mickey – Now you have created the house, it has lots of features, it is a multi-story house with many rooms, a play area, kitchen, and washing area, it has moving doors and windows
Minnie – Oh my God, I am back in childhood
Mickey – Now just imagine you decide to keep this big lego house in a common area and any of your friends or you can go there and make changes or add new blocks, remove old blocks, etc
Minnie – Ok, sounds cool
Mickey – However, here is a problem, if people are making the changes independently and randomly without the presence of others, it can cause problems
Minnie – Ok
Mickey – Can you think of what can be the issues
Minnie – Yeah, I know, Let’s say I made a change in the doors to make them sliding vs hinged doors, and others will not know about it
If some other friend added a block adjacent to the door, the door will not open and it will not work
Mickey – Exactly, and this is what happens in Software Projects. Let’s say our Development team is working on a software application and if they work in silos and they don’t communicate the changes made by them to the team in a proper way, these kinds of issues will come regularly
Minnie – Oh Yes!
Mickey – If one person makes a change in one of the modules, it may break the changes done by some other developer in the same of different module
Minnie – Yes, I can get that
Mickey – Now let’s imagine, if we keep our Project at a common central repository and when any person wants to make any changes to the code, they will get a copy of the code from the central repository and work on it on their local systems
Minnie – Good, so we are now not making changes directly to the main project but making a copy of it and working on our local systems
Mickey – Yes, And after working, they merge the changes back to the code on the central repository and this commit of change triggers some automated tests, which run to check if the final code is working fine and nothing is broken
Minnie – Wow! That will be awesome, It will save so much time and effort and will make the collaboration so efficient and organized
Mickey – Yes, and that exactly is CI – Continuous Integration
Continuous integration (CI): A software development practice in which developers regularly merge (integrate) their code changes into a central repository, and automated builds and tests are run
This helps catch integration issues early and ensures that the codebase is always in a deployable state
Minnie – Wow, I can understand the process now
Mickey – In CI, we need a platform to keep our project/code, we call it Repository
Minnie – Ok
Mickey – Can you think of any such platform
Minnie – Hmm… GitHub?
Mickey – Yes, GitHub is very common, then there is BitBucket, GitLab, etc
And, we also need a tool that will help to pull, push and commit changes
Minnie – Will that be Git?
Mickey – Yes, any Source code management tools like Git, SVN, Mercurial, etc
And we also need a platform where we can create jobs to run when the changes and commit to code happens
Can you think of a tool where we can create and chain multiple stages or jobs?
Minnie – I know, Jenkins?
Mickey – Exactly, there can be others like Bamboo, TeamCity, GitLab etc, So here on Jenkins we can create jobs to run some tests whenever there is a commit in the common repository
Minnie – Great
Mickey – So, whenever any developer will make any changes on the common code repository, it will trigger a Jenkins job, that will in turn run some jobs to do automated builds and run some tests to check the code is stable after the change and nothing else is breaking
Minnie – What if the tests fail?
Mickey – If the test fails, the team will know that this particular change is causing the issue and it can be reverted immediately
Minnie – Wow, that will save so much time and efforts
Mickey – Exactly, So to make Continuous Integration work we need
A Common Repository (like GitHub)
A Source code Management tool (like Git)
A CI Tool (like Jenkins)
Minnie – And a team to work on this
Mickey – Of, course Minnie
Minnie – Wow, I can join the dots now
Mickey – Now when we also add a stage of testing and builds that make the code ready for release, it will be called Continuous Delivery (CD)
Minnie – So Continuous Delivery is CI + jobs to test and make the build ready for release
Mickey – Yes, and when we further add the Release process to this chain it becomes Continuous Deployment (CD)
Minnie – Okay this clears the terms Continuous Integration, Delivery and Deployment, I feel so good now
Mickey – Great, Do you want to get a Pizza?
Minnie – No let’s sit here for some time. I want to enjoy the sunset
Mickey – Sure, Minnie
Minnie – You are my best friend
Mickey – I am always here for you 🙂
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