Trunk-Based Development

Overview Managing source code effectively is the difference between a streamlined release and a chaotic debugging session. This guide explores the mechanical and strategic nuances of Git branching. By using a FastAPI web application as a concrete example, we demonstrate how to isolate new features, maintain a clean history, and choose between different integration strategies like merging and rebasing. Understanding these patterns allows you to collaborate without stepping on your teammates' toes. Prerequisites To follow this tutorial, you should have a baseline understanding of Python syntax and the basic concept of version control. You will need a terminal environment, Git installed, and a package manager like UV or pip. Familiarity with basic HTTP methods (GET) and unit testing with Pytest is also beneficial. Key Libraries & Tools * **FastAPI**: A modern, fast (high-performance) web framework for building APIs with Python. * **GitKraken**: A visual Git client that simplifies branch management and history visualization. * **UV**: An extremely fast Python package installer and resolver. * **Pytest**: A framework that makes it easy to write small, readable tests. Code Walkthrough Initializing the API We start by defining a simple root endpoint. This serves as our stable baseline on the `main` branch. ```python from fastapi import FastAPI app = FastAPI() @app.get("/") def read_root(): return {"Hello": "World"} ``` Isolating Features via Branches Instead of modifying `main` directly, create a feature branch. This keeps the production-ready code clean while you experiment. We add a new `goodbye` endpoint and a corresponding unit test to verify it works. ```python @app.get("/goodbye") def say_goodbye(name: str = "World"): return {"message": f"Goodbye {name}"} ``` Merging vs. Rebasing When it is time to bring changes back to `main`, you face a choice. A **Standard Merge** creates a new commit that ties the two histories together. This preserves the exact context of when a feature was developed but can lead to a "spaghetti" visual history. **Rebasing** offers a cleaner alternative. It takes your feature commits, sets them aside, moves your branch to the tip of the current `main`, and then reapplies your work on top. This results in a perfectly linear history. If `main` hasn't changed since you branched, Git performs a **Fast-Forward**, simply moving the branch pointer forward without creating a new commit at all. Syntax Notes * **Feature Flags**: When using Trunk-Based Development, use boolean constants to toggle code paths. This allows you to merge unfinished code safely. * **Naming Conventions**: In GitFlow, prefix branches with `feature/` or `hotfix/` to organize the repository automatically. Practical Examples Real-world teams often use **GitFlow** for structured releases where separate `develop` and `main` branches exist. Alternatively, fast-moving startups might prefer **Trunk-Based Development**, pushing directly to `main` while hiding incomplete features behind logic toggles to avoid long-lived branch conflicts. Tips & Gotchas * **Rewrite History with Caution**: Never rebase a branch that others are also working on. It changes commit hashes and will break their local environments. * **Small Commits**: Commit early and often. Smaller commits make resolving merge conflicts significantly easier. * **Test Before Integration**: Always run Pytest on your feature branch before merging to ensure you aren't introducing regressions.