Module 1 Lesson 1: What is CI/CD?
Master the fundamental concepts of Continuous Integration and Continuous Delivery. Learn why automation is the heartbeat of modern software engineering.
Module 1 Lesson 1: What is CI/CD?
In the "Old days" of software, developers would write code for months, then hand it off to a "Release Team" who would spend 2 days manually building and deploying the app. If something broke, it took weeks to fix.
CI/CD changes everything by turning the "Release" process into a collection of automated scripts.
1. Continuous Integration (CI)
CI is the practice of frequently merging your code into a shared repository (usually main).
- The Workflow:
- Developer pushes code.
- An automated server (the "Runner") immediately builds the app.
- The runner executes every test you've written.
- The Goal: Catch bugs immediately, before they are merged and affect other developers.
2. Continuous Delivery (CD)
Continuous Delivery takes CI one step further. It ensures that every single commit that passes your tests is ready to be deployed at the click of a button.
- Manual Gate: In Delivery, a human still clicks the "Deploy to Production" button.
3. Continuous Deployment (CD)
This is the "Gold Standard." Every commit that passes the tests is automatically pushed to the live website without any human intervention.
- Risk vs Reward: This requires extremely high-quality tests, but it allows a company like Amazon to deploy new code every 11 seconds.
4. Why Use GitLab?
While there are many tools (Jenkins, GitHub Actions, CircleCI), GitLab is unique because the CI/CD engine is built into the source code repository itself.
- You don't need to connect 5 different tools.
- Your code, your tests, your registry, and your deployment logs are all on one screen.
Exercise: The Manual vs Auto Audit
- How long does it take you to manually "Build" and "Upload" your latest project? (Include the time spent waiting for things to download!).
- If you found a critical spelling mistake on your homepage, how many "Manual Steps" would it take to fix it right now?
- Name one risk of Continuous Deployment (Full Automation) that would keep a CEO awake at night.
- Research: What is a "Broken Build" policy, and why do some teams wear a "Cape of Shame" when they break the build?
Summary
CI/CD is not just about tools; it's a Cultural Shift. It moves the team from a cycle of "Big, Scary Releases" to a cycle of "Small, Constant Improvements." In this course, we will master the technical side of making this a reality using GitLab.
Next Lesson: From scripts to pipelines: The history and evolution of DevOps.