Azure Repos for source control - Deep Dive

Overview - Azure Repos for source control

What is it?

Azure Repos is a service that helps teams store and manage their code safely in the cloud. It provides a place where developers can save their work, track changes, and collaborate with others. It supports popular version control systems like Git and Team Foundation Version Control (TFVC). This makes it easier to work together on software projects without losing track of changes.

Why it matters

Without a system like Azure Repos, teams would struggle to keep track of code changes, leading to lost work, confusion, and errors. It solves the problem of managing multiple versions of code and coordinating work among many developers. This helps deliver software faster and with fewer mistakes, which is important for businesses and users relying on software products.

Where it fits

Before learning Azure Repos, you should understand basic software development and the idea of saving files. After Azure Repos, you can learn about continuous integration and deployment, which use source control to automate software delivery. Azure Repos is a foundational tool in the journey of modern software development and DevOps practices.

Mental Model

Core Idea

Azure Repos is like a shared, secure notebook where every change to your code is saved and tracked so teams can work together smoothly.

Think of it like...

Imagine a group of friends writing a story together in a shared notebook. Each friend writes their part on different pages, and the notebook keeps a history of every change so no one loses their work or overwrites someone else's story.

┌─────────────────────────────┐
│        Azure Repos          │
├─────────────┬───────────────┤
│   Git Repo  │   TFVC Repo   │
├─────────────┴───────────────┤
│  Tracks changes and history │
│  Supports collaboration     │
│  Stores code securely       │
└─────────────────────────────┘

Build-Up - 7 Steps

1

Foundation

What is Source Control

Concept: Introduce the basic idea of source control as a way to save and track changes in files.

Source control is like saving versions of your work so you can go back if needed. It keeps a history of changes and who made them. This helps avoid losing work and makes teamwork easier.

Result

You understand why saving versions of code is important and how it helps teams avoid mistakes.

Understanding source control is key because it prevents lost work and confusion when multiple people change the same files.

2

Foundation

Introduction to Azure Repos

Concept: Explain Azure Repos as a cloud service that provides source control using Git and TFVC.

Azure Repos stores your code in the cloud and tracks changes using Git or TFVC. It allows many developers to work on the same project safely and see each other's changes.

Result

You know what Azure Repos is and how it fits into managing code for teams.

Knowing Azure Repos offers both Git and TFVC helps you choose the right tool for your team's needs.

3

Intermediate

Working with Git in Azure Repos

🤔Before reading on: do you think Git stores full copies of files each time or just changes? Commit to your answer.

Concept: Learn how Git works in Azure Repos by storing snapshots of changes and enabling branching.

Git saves snapshots of your project at different points, not full copies every time. Azure Repos lets you create branches to work on features separately, then merge them back safely.

Result

You can create branches, commit changes, and merge code in Azure Repos using Git.

Understanding Git's snapshot and branching model explains why it is fast and flexible for teamwork.

4

Intermediate

Using Pull Requests for Collaboration

🤔Before reading on: do you think pull requests automatically change code or require review first? Commit to your answer.

Concept: Pull requests let team members review and discuss code changes before merging them.

In Azure Repos, a pull request is a way to ask others to check your code changes. This helps catch mistakes and improve quality before the code becomes part of the main project.

Result

You can create and review pull requests to collaborate effectively and keep code quality high.

Knowing pull requests enforce review helps teams maintain better code and avoid bugs.

5

Intermediate

Understanding TFVC in Azure Repos

Concept: Introduce Team Foundation Version Control as an alternative centralized system in Azure Repos.

TFVC stores code in a central server and tracks changes with check-ins. Unlike Git, it uses a single main version and can lock files during edits to avoid conflicts.

Result

You understand how TFVC differs from Git and when it might be used.

Recognizing TFVC's centralized model helps when working with legacy projects or teams preferring strict control.

6

Advanced

Branch Policies and Automation

🤔Before reading on: do you think branch policies allow or prevent merging without checks? Commit to your answer.

Concept: Branch policies in Azure Repos enforce rules like required reviews and successful builds before merging code.

You can set policies that require pull requests to be approved and pass automated tests before code merges. This keeps the main code safe and stable.

Result

Your team can maintain high code quality and reduce bugs by enforcing branch policies.

Knowing how to automate quality checks prevents broken code from reaching production.

7

Expert

Scaling Azure Repos for Large Teams

🤔Before reading on: do you think large teams should use many small repos or one big repo? Commit to your answer.

Concept: Learn strategies for organizing repositories and managing permissions in big organizations.

Large teams often split code into multiple repos to keep things manageable. Azure Repos supports fine-grained permissions and integration with Azure DevOps pipelines for smooth workflows.

Result

You can design source control setups that scale well and keep teams productive.

Understanding repo organization and permissions is crucial to avoid chaos and maintain security in big projects.

Under the Hood

Azure Repos stores code in repositories using Git or TFVC. Git works by saving snapshots of the entire project at each commit, using a directed acyclic graph to track history and branches. TFVC uses a centralized server model with check-ins and file locking. Azure Repos integrates with Azure DevOps services to provide pull requests, branch policies, and permissions. The system manages metadata about changes, users, and branches to enable collaboration and history tracking.

Why designed this way?

Azure Repos was designed to support both distributed (Git) and centralized (TFVC) version control to accommodate different team preferences and legacy needs. The integration with Azure DevOps allows seamless workflows from code to deployment. The design balances flexibility, security, and scalability to serve small teams and large enterprises alike.

┌───────────────┐       ┌───────────────┐
│   Developer   │──────▶│   Azure Repos │
└───────────────┘       └───────────────┘
        ▲                      │
        │                      ▼
┌───────────────┐       ┌───────────────┐
│   Local Git   │◀─────▶│  Git Repo DB  │
│   Repository  │       └───────────────┘
└───────────────┘

TFVC Model:
┌───────────────┐       ┌───────────────┐
│   Developer   │──────▶│   TFVC Server │
└───────────────┘       └───────────────┘

Myth Busters - 4 Common Misconceptions

Quick: Does Azure Repos only support Git? Commit to yes or no.

Common Belief: Azure Repos only supports Git repositories.

Reality: Azure Repos supports both Git and Team Foundation Version Control (TFVC) repositories.

Why it matters: Assuming only Git is supported may lead teams to overlook TFVC, which might better fit their workflow or legacy projects.

Quick: Do pull requests automatically merge code without review? Commit to yes or no.

Common Belief: Pull requests in Azure Repos merge code automatically without any review.

Reality: Pull requests require explicit review and approval before merging, enforcing collaboration and quality checks.

Why it matters: Believing pull requests merge automatically can cause teams to skip important code reviews, increasing bugs.

Quick: Is branching in Git slow and resource-heavy? Commit to yes or no.

Common Belief: Creating branches in Git is slow and uses a lot of storage.

Reality: Git branches are lightweight pointers to commits, making branching fast and efficient.

Why it matters: Misunderstanding branching costs can discourage teams from using branches effectively, limiting parallel development.

Quick: Does TFVC lock files by default during edits? Commit to yes or no.

Common Belief: TFVC never locks files during editing.

Reality: TFVC can lock files during check-out to prevent conflicting edits, unlike Git's distributed model.

Why it matters: Ignoring file locking behavior can cause confusion about how concurrent edits are managed in TFVC.

Expert Zone

1

Azure Repos integrates deeply with Azure Pipelines, enabling automated testing and deployment triggered by code changes.

2

Branch policies can be customized per branch, allowing different rules for development, release, or hotfix branches.

3

Azure Repos supports large file storage (Git LFS) for handling big assets efficiently, which is often overlooked.

When NOT to use

Azure Repos may not be ideal if your team prefers other version control systems like Mercurial or Subversion, or if you require on-premises hosting without Azure DevOps Server. Alternatives include GitHub, GitLab, or Bitbucket for cloud Git hosting, or local Git servers for isolated environments.

Production Patterns

In production, teams use Azure Repos with feature branching, pull requests, and branch policies to maintain code quality. Repos are often organized by microservices or components. Integration with Azure Boards tracks work items linked to commits. Automated pipelines run tests and deployments on pull request merges, enabling continuous delivery.

Connections

Continuous Integration and Continuous Deployment (CI/CD)

Builds-on

Understanding Azure Repos is essential to grasp how CI/CD pipelines trigger automated builds and deployments from source code changes.

Distributed Version Control Systems

Same pattern

Azure Repos' Git support follows the distributed version control model, which is a fundamental concept in modern software collaboration.

Collaborative Writing Tools

Similar pattern

Like Google Docs tracks edits and comments for shared documents, Azure Repos tracks code changes and discussions, showing how collaboration principles apply across fields.

Common Pitfalls

#1 Ignoring branch policies and merging code without review.

Wrong approach:

Merge pull requests directly without setting or following branch policies.

Correct approach:

Configure branch policies to require code reviews and successful builds before merging pull requests.

Root cause:

Misunderstanding the importance of automated checks and peer reviews leads to lower code quality and more bugs.

#2 Using a single large repository for all projects without organization.

Wrong approach:

Store all code for multiple unrelated projects in one big Azure Repo repository.

Correct approach:

Create separate repositories for different projects or components to keep code manageable and permissions clear.

Root cause:

Not planning repository structure causes confusion, slower operations, and harder collaboration.

#3 Assuming TFVC and Git behave the same way.

Wrong approach:

Treat TFVC like Git by expecting distributed workflows and lightweight branching.

Correct approach:

Understand TFVC uses centralized version control with check-ins and file locking, requiring different workflows.

Root cause:

Lack of knowledge about version control models leads to workflow mismatches and frustration.

Key Takeaways

Azure Repos is a cloud service that stores and tracks code changes using Git or TFVC to help teams collaborate safely.

Git in Azure Repos uses snapshots and branches to enable fast, flexible development, while TFVC offers a centralized model with file locking.

Pull requests and branch policies in Azure Repos enforce code reviews and automated checks, improving code quality.

Organizing repositories and permissions thoughtfully is crucial for scaling Azure Repos in large teams.

Understanding Azure Repos deeply connects to broader DevOps practices like CI/CD and collaborative workflows.