Introduction to Continuous Integration (CI)

What CI means

Continuous Integration is the practice of:

• merging changes frequently
• automatically running checks on every change

Typical checks:

• unit tests
• linting
• type checks
• security scans

Why CI matters

CI prevents:

• “works on my machine”
• long-lived branches
• late discovery of integration issues

Diagram: CI feedback loop

diagram Diagram mermaid

  graph LR
A[Commit / PR] --> B[CI pipeline]
B --> C{Checks pass?}
C -- Yes --> D[Merge]
C -- No --> E[Fix + push]
E --> B

Good CI characteristics

• fast (minutes, not hours)
• deterministic
• provides clear failure messages
• runs on PRs before merge

Visualize it

A typical CI pipeline runs a chain of automated checks after every push, and only deploys once all of them pass.

diagram CI Pipeline mermaid

  flowchart LR
A["git push"] --> B["CI triggers"]
B --> C["Install deps"]
C --> D["Run linters"]
D --> E["Run tests"]
E --> F["Build"]
F --> G["Deploy (if all pass)"]

A CI pipeline runs automated checks and builds after every push, deploying only if everything passes.