Trunk-based development vs feature-based development

Trunk-based development and feature-based development are two widely used version control strategies for developing software in a team setting. In trunk-based development, developers commit code changes directly to a single main branch (trunk), whereas in feature-based development, developers create separate branches for individual features or tasks, merging them back into the main branch once the features are complete.

Your choice of branching strategy can influence a range of factors in your project, from the efficiency of your development process to the ease of managing code integration and the overall stability of your codebase.

In this article, you’ll explore the differences between trunk-based development and feature-based development and how to decide which approach is right for your team.

What is trunk-based development?

Trunk-based development is a software branching model in which all developers commit their code changes directly to a single main branch, known as the “trunk. This technique emphasizes the importance of making small, incremental changes, integrating them with the main branch as soon as possible, and ensuring the codebase is always in a deploy-ready state.

Trunk based development doesn’t prohibit the use of branches outright. If a coding activity requires more extensive time — perhaps a few days — developers can check out a branch from main, move the changes into it, then merge it back in when development is complete. The crucial thing about checked-out branches is that they are short-lived and that changes are small in scope so that integration back into the main branch is smooth and manageable. This practice ensures that the codebase remains cohesive, up-to-date, and ready for deployment. minimizing the risks of merge conflicts and integration issues.

In a trunk-based workflow, the main branch should always be production-ready. Faulty code can break the entire build and result in a complicated development history. That means that teams should thoroughly test each code change before pushing them to the main branch. Short development cycles and automated testing enable teams to identify defects early and recover from failed builds quickly, supporting faster, more efficient delivery cycles.

What is feature-based development?

In feature-based development — also known as the GitFlow model — developers create separate, long-lived branches for individual features or tasks. Depending on the complexity of the feature, developers can work on a feature branch for days, weeks, or even months. Only after the feature is complete and thoroughly tested is it merged back into the main branch.

This approach provides a clear separation of concerns, making it easier to manage and test new features in isolation. Each feature branch is developed independently of the main branch, allowing developers to work on new functionality without affecting the stability of the main codebase. Most importantly, developers never push code changes directly to the main branch in the feature-based workflow.

The advantage of feature-based workflows is that hundreds of developers can work on hundreds of unique features at any given time. They can carry out feature development in small phases so that multiple merge requests do not conflict with one another.

Managing feature-based development can be tricky, though, especially when multiple pull requests are queued to merge into the main branch. Long-lived branches can diverge significantly from the main codebase, leading to long, complicated builds and difficult-to-debug merge conflicts. Ultimately, these issues can reduce deployment frequency and hamper product innovation.

Despite the difficulties, there are situations in which you and your team may want to consider a feature-based workflow.

For example, sometimes you must maintain multiple software versions. In these cases, a trunk-based workflow may be challenging to implement. The Linux kernel is a classic use case for feature-based development and uses long-lived release branches. The feature-based workflow is the most sensible solution in this situation because users may have to maintain each released version of the Linux kernel for years — possibly even decades.

Importance of trunk-based workflows in CI/CD

One of the greatest benefits of trunk-based workflows is that they integrate well with continuous integration and continuous delivery (CI/CD). When you push each commit to the main branch, you can run automated tests (part of CI) to verify that the new changes do not break the main branch. Then, after all the tests successfully terminate, you can configure a pipeline to automatically deploy the changes to production or staging environments (part of CD).

Trunk-based development and CI/CD support agile software delivery by enabling teams to make frequent, incremental updates and deploy them to production with minimal manual intervention. This approach aligns with agile principles that emphasize iterative progress, responsiveness to user needs, and continuous improvement.

Feature-based development, on the other hand, has long development cycles and messy integrations. Large-scale integrations can add a substantial amount to the time it takes to approve and ship new changes. This can hinder the responsiveness and flexibility that agile methodologies aim to achieve, as teams may spend significant time resolving integration issues instead of delivering value to users.

How to implement trunk-based development

The biggest hurdle for many teams in adopting trunk-based development is the shift in mindset required to commit smaller, more frequent changes. If you are used to working with long-lived branches and merging complete features after prolonged development periods, adjusting to a more incremental approach can be challenging.

To get the most out of the trunk based model, you will want to automate as much of your development pipeline as possible. Implementing a robust CI/CD pipeline can ease the transition to faster delivery cycles by eliminating manual testing and review requirements and automatically deploying changes to your production environment.

To implement trunk based development, follow these steps:

Set up your version control system (VCS): Choose a Git-based VCS and ensure all team members have access. Then create a central repository and establish the main branch as the trunk.
Implement CI/CD: A CI/CD platform like CircleCI will automate the build, test, and deployment phases of your workflow. You can set up your pipeline to trigger automated tests on every commit to the main branch, then deploy passing builds to staging or production environments.
Develop a robust automated test suite: Create a comprehensive suite of unit tests, integration tests, and end-to-end tests to ensure that all aspects of your code are thoroughly tested by your CI platform.
Merge frequently: Encourage developers to commit and merge their changes to the main branch frequently. Tasks that require more than a few hours may use short-lived feature branches, but they should be merged back into the main branch as soon as the changes are complete and tested.
Monitor and address build failures immediately: Your CI/CD platform will notify you of any failed builds, and it is crucial that your team prioritizes fast recovery to keep the main branch stable and deployable.
Review and iterate: Regularly review the trunk-based development process and make adjustments as needed. Collect feedback from your team and monitor key engineering metrics for opportunities to improve.

By following these recommendations, you can set up a trunk-based development workflow that will accelerate development, improve code quality, and prevent painful merge conflicts from disrupting your team’s progress.