What is Trunk-Based Development?

Trunk-Based Development (TBD) is a source control branching model where developers collaborate on code in a single branch called 'trunk' (or 'main' in Git), resisting any pressure to create long-lived feature branches. In this approach, developers work in small batches and commit to the trunk at least once per day, enabling continuous integration and reducing merge conflicts.

This development pattern stands in contrast to complex branching strategies that can lead to integration challenges, delayed feedback, and deployment bottlenecks. By keeping all developers working together in a single branch, TBD promotes collaboration, simplifies workflows, and accelerates the delivery pipeline.

Why Trunk-Based Development Matters

In today's fast-paced software development landscape, speed and reliability are paramount. Organizations are under constant pressure to deliver new features quickly while maintaining high quality. Trunk-Based Development directly addresses these challenges by:

  • Reducing integration pain: With frequent merges to the main branch, integration issues are discovered and resolved early
  • Accelerating feedback cycles: Changes are continuously integrated, tested, and validated
  • Enabling Continuous Delivery: TBD is a prerequisite for true Continuous Delivery and Deployment
  • Improving collaboration: All team members work from the same codebase, enhancing visibility and knowledge sharing
  • Decreasing time-to-market: Features can be completed and deployed more rapidly with fewer process-related delays

According to the State of DevOps Report, high-performing teams are significantly more likely to use Trunk-Based Development. These teams deploy code 208 times more frequently and have 106 times faster lead time from commit to deploy compared to low-performing teams.

Trunk-Based Development vs. Other Branching Strategies

While other branching strategies like GitFlow have their place in specific contexts, they often introduce complexity and delays that modern development teams can't afford. Trunk-Based Development offers a streamlined alternative that aligns perfectly with continuous delivery practices.

The key difference is that TBD optimizes for continuous integration and small, incremental changes rather than isolating work in long-lived branches. This fundamental shift in approach enables teams to move faster with greater confidence.

Implementing Trunk-Based Development: A Step-by-Step Guide

1. Start with a Cultural Shift

Before changing any technical practices, it's essential to address the cultural aspects of moving to Trunk-Based Development:

  • Educate the team: Ensure everyone understands the benefits and principles of TBD
  • Set clear expectations: Establish guidelines for commit frequency and size
  • Emphasize collaboration: Encourage pair programming and code reviews
  • Build trust: Create a safe environment where team members feel comfortable committing frequently

2. Establish a Solid Testing Foundation

Trunk-Based Development relies heavily on automated testing to maintain quality:

  • Implement comprehensive unit tests: Aim for high test coverage of critical paths
  • Add integration tests: Ensure components work together as expected
  • Set up end-to-end tests: Validate complete user journeys
  • Create a fast feedback loop: Tests should run quickly to support frequent commits

3. Implement Continuous Integration

A robust CI pipeline is essential for Trunk-Based Development:

  • Automate builds: Every commit should trigger an automated build
  • Run tests automatically: All tests should execute on each commit
  • Enforce quality gates: Set up code quality checks and test coverage requirements
  • Make build status visible: Ensure the team can easily see the current state of the trunk

4. Adopt Feature Flags for Incomplete Work

Feature flags are the secret weapon that makes Trunk-Based Development practical for teams of all sizes:

  • Hide incomplete features: Use feature flags to disable code that isn't ready for production
  • Enable targeted testing: Activate features for specific users or environments
  • Facilitate gradual rollouts: Incrementally release features to manage risk
  • Support experimentation: Test different implementations with real users

With Devunus, implementing feature flags becomes straightforward:

// Example of using Devunus for feature flagging
function renderCheckout() {
  if (devunus.isEnabled('new-checkout-flow')) {
    return <NewCheckoutFlow />
  } else {
    return <LegacyCheckoutFlow />
  }
}

5. Master Short-Lived Feature Branches

While Trunk-Based Development emphasizes working directly on the trunk, short-lived feature branches can still play a role:

  • Keep branches short-lived: Merge branches back to trunk within 1-3 days
  • Make small, focused changes: Each branch should represent a single logical change
  • Rebase frequently: Keep branches up-to-date with the latest trunk changes
  • Use pull requests for code review: Review code before merging to maintain quality

6. Implement Branch by Abstraction for Larger Changes

For significant refactoring or architectural changes that can't be completed in a day:

  • Create an abstraction layer: Introduce an interface that allows both old and new implementations
  • Build the new implementation: Develop the new code behind the abstraction
  • Gradually migrate: Switch components to the new implementation one by one
  • Remove the old implementation: Once migration is complete, remove the old code 
class PaymentProcessor {
  processPayment(order) {
    if (devunus.isEnabled('new-payment-system')) {
      return this.processWithNewSystem(order);
    } else {
      return this.processWithLegacySystem(order);
    }
  }

  processWithLegacySystem(order) {
    // Legacy implementation
  }

  processWithNewSystem(order) {
    // New implementation
  }
}

7. Establish Clear Communication Channels

Effective communication is crucial when multiple developers work on the same codebase:

  • Regular stand-ups: Discuss current work and potential conflicts
  • Shared task board: Maintain visibility of who is working on what
  • Chat channels: Create dedicated channels for build status and trunk updates
  • Documentation: Keep architecture and design decisions well-documented

Overcoming Common Challenges

Challenge: Merge Conflicts

Solution: Commit frequently (at least daily), keep changes small, and communicate actively with team members working on related code.

Challenge: Breaking the Build

Solution: Implement branch protection rules on your main branch that require status checks (builds, tests) to pass, pull request reviews to be approved, and branches to be up-to-date before merging. Combined with automated CI/CD pipelines and blocked force pushes, these safeguards ensure only working code reaches the trunk while maintaining a stable and reliable main branch.

Challenge: Incomplete Features

Solution: Use feature flags to hide incomplete work, allowing code to be merged to trunk without affecting users.

Challenge: Code Review Bottlenecks

Solution: Implement pair programming, establish clear review guidelines, and keep changes small to facilitate faster reviews.

Feature Flags: The Enabler of Trunk-Based Development

Feature flags are essential to successful Trunk-Based Development, allowing teams to:

  • Commit incomplete code: Developers can commit work-in-progress without affecting users
  • Deploy frequently: Every commit can potentially go to production, even with incomplete features
  • Test in production: Features can be enabled for testing in the production environment
  • Roll back problematic features: Issues can be addressed by disabling features rather than rolling back deployments

For a deeper dive into feature flags and their strategic advantages, check out our comprehensive guide to feature flags.

How Devunus Enhances Trunk-Based Development

Devunus provides a comprehensive feature management platform that makes implementing Trunk-Based Development significantly easier:

  • Centralized flag management: Control all feature flags from a single dashboard
  • Sophisticated targeting: Enable features for specific users, regions, or other criteria
  • Real-time updates: Change flag states instantly without redeploying
  • Gradual rollouts: Implement percentage-based deployments to manage risk
  • A/B testing: Compare different implementations with real users
  • Analytics: Track the impact of feature releases on key metrics
  • Cross-platform support: Consistent feature flag behavior across all your applications 
// Example of targeted rollout with Devunus
if (devunus.getFeatureStatus('new-ui', {
  userId: user.id,
  userRole: user.role,
})) {
  // Show new UI
} else {
  // Show existing UI
}

Measuring Success with Trunk-Based Development

To ensure your Trunk-Based Development implementation is effective, track these key metrics:

  • Lead time: Time from first commit to production deployment
  • Deployment frequency: How often you deploy to production
  • Change failure rate: Percentage of deployments causing incidents
  • Mean time to recovery: How quickly you recover from incidents
  • Build success rate: Percentage of builds that pass all tests
  • Code review time: How long it takes to review and merge code

Continuous Delivery: The Natural Next Step

Trunk-Based Development is a foundational practice for Continuous Delivery (CD), which takes the concept further by ensuring your software is always in a releasable state. With TBD in place, implementing CD becomes much more achievable:

  • Automate the deployment pipeline: Create a fully automated path to production
  • Implement progressive delivery: Use feature flags to gradually roll out changes
  • Decouple deployment from release: Deploy code without immediately releasing features
  • Monitor production closely: Implement robust monitoring and alerting
  • Practice incident response: Ensure the team can quickly respond to issues

Conclusion: Embracing Modern Development Practices

Trunk-Based Development represents a shift toward more efficient, collaborative, and reliable software delivery. By combining TBD with feature flags through Devunus, teams can achieve:

  • Faster time-to-market for new features
  • Reduced integration problems and merge conflicts
  • Improved code quality through continuous integration
  • Greater flexibility in feature release and testing
  • Enhanced collaboration across development teams

The most successful software organizations have already embraced these practices, gaining significant competitive advantages in speed and reliability. By implementing Trunk-Based Development with Devunus feature management, your team can join the ranks of high-performing development organizations delivering better software faster.

Learn more about how Devunus can help you implement Trunk-Based Development on our feature flags product page.