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Trunk Based Development vs GitLab Flow

In modern software development, choosing the right branching strategy significantly impacts team productivity and deployment quality. This article compares two popular branching strategies: "Trunk Based Development" and "GitLab Flow", explaining their features and how to choose between them.

Trunk Based Development​

Trunk Based Development is a methodology where all developers merge code into the "trunk" (main branch) frequently (at least once a day).

Key Features​

  • Short-lived Branches: Feature branches are merged and deleted within hours or days.
  • Frequent Integration: Code changes are kept small, minimizing the risk of merge conflicts.
  • Feature Flags: Incomplete features are hidden in production using Feature Toggles.

Pros​

  • Fast Feedback: Frequent CI execution allows for early bug detection.
  • Reduced Merge Pain: Small diffs make large conflicts less likely.
  • Easy Deployment: The trunk is always kept in a deployable state.

Cons​

  • High Discipline Required: Requires mature test automation and code review processes.
  • Feature Flag Management: Managing flags incurs costs and can become technical debt.

GitLab Flow​

GitLab Flow aims to resolve the complexity of GitFlow while emphasizing environment management more than Trunk Based Development. It adds the concept of "environment branches" or "release branches" to GitHub Flow.

Key Features​

  • Environment Branches: Has branches corresponding to deployment environments, such as production or pre-production.
  • Upstream First: All changes are first merged into the main branch, then cherry-picked or merged downstream to environment branches.
  • Release Branches: Creates stable branches from main when versioning is required.

Pros​

  • Easy Environment Management: The state of staging and production environments is visualized as branches.
  • Clear Bug Fix Flow: Enforces a flow where fixes are made in main and then applied to each environment.
  • CI/CD Affinity: Easy to trigger deployment pipelines based on pushes to specific branches.

Cons​

  • Branch Management Overhead: Requires managing multiple long-lived branches compared to trunk-based.
  • Deployment Latency: Changes may go through multiple stages before reaching production after merging to main.

Deployment and Release Best Practices​

Here are the best practices for deployment flows and Git tag usage for each strategy.

For Trunk Based Development​

In Trunk Based Development, the principle of "Build Once, Promote Everywhere" is crucial.

Deployment Flow (Dev -> Staging -> Prod)​

  1. Commit & Build: When a developer commits to main, CI runs and generates artifacts (e.g., Docker images).
  2. Deploy to Dev: The generated artifact is automatically deployed to the Dev environment.
  3. Promote to Environments: The same artifact is sequentially deployed (promoted) to Staging and Production based on approval processes or automated test results.
    • Important: Do not rebuild for each environment. Manage binaries/images, not source code, across environments.

Git Tag Usage​

  • Release Tags: Create a tag (e.g., v1.0.0) on the main branch commit at the time of release.
  • Automation: It is common to automatically tag upon successful deployment to production within the deployment pipeline.

For GitLab Flow​

GitLab Flow is based on the principle that "Branch state represents environment state".

Deployment Flow (Dev -> Staging -> Prod)​

  1. Dev Environment: Deployed to the Dev environment as soon as feature branches are merged into main.
  2. Staging Environment: Merging (or creating a Pull Request) from main to the pre-production branch triggers deployment to the Staging environment.
  3. Prod Environment: After verification in pre-production, merging to the production branch triggers deployment to the Production environment.

Git Tag Usage​

  • Release Tags: Create a tag (e.g., v1.0.0) on the commit merged into the production branch.
  • Release Branches: If long-term maintenance is required (e.g., for packaged software), create release branches like stable-1.0 and manage patch version tags (v1.0.1) on that branch.

Comparison Summary​

FeatureTrunk Based DevelopmentGitLab Flow
Branch LifespanExtremely shortEnvironment/Release branches are long-lived
Merge FrequencyHigh (multiple times/day)Per feature, per release
Deployment StrategyFeature Flags, Blue/GreenMerge to environment branches
ComplexityLow (High operational skill)Medium
Suitable TeamsSenior-heavy, fast iteration teamsAgency work, teams needing strict release management

Which one should you choose?​

Choose Trunk Based Development if:​

  • You are developing a SaaS or Web service with continuous updates.
  • You have high test automation coverage and a robust CI/CD pipeline.
  • Your team members are skilled and comfortable integrating small changes frequently.

Choose GitLab Flow if:​

  • You need approval processes across multiple environments (QA, Staging, Production).
  • You need versioned releases, such as for mobile apps or packaged software.
  • Your team is not yet fully adapted to CI/CD and needs a staged deployment flow.

Conclusion​

If speed and agility are your top priorities, you should aim for Trunk Based Development. However, if organizational constraints or release policies require environment separation, GitLab Flow is a realistic solution. The key is to gradually optimize your process according to your team's skill level and project requirements.