Introduction

Moving toward true continuous integration means eliminating long-lived branches and merging code into the main branch daily. If an incomplete feature reaches production, the impact can be immediate. This is where Feature Flags stop being an optional tool and become strategic infrastructure.

Background: the hidden risk in continuous integration

Before implementing Feature Flags in the backend, there was a structural asymmetry:

• Only the frontend used flags.
• Incomplete features had no isolation mechanism in the backend.
• External solutions (FFaaS) implied high costs and third-party dependence.
• There was no clear policy for flag management, expiration, or cleanup.

In that context, adopting Trunk-Based Development without a control layer would have been technically reckless. Integrating changes daily into the main branch without a controlled activation mechanism means any partially developed feature could impact production. The problem was not only technical. It was one of governance, operational risk, and architectural sustainability.

Core idea: design a system, not just a tool

The goal was not simply to toggle features on or off. It was to build a structural layer that would allow:

• Safe continuous integration.
• Compatibility with open standards (OpenFeature).
• Minimizing vendor lock-in risk.
• Controlling the operational debt associated with flags.
• Scaling without future friction.

It wasn’t about buying a product; it was about aligning architecture with engineering strategy. The decision to develop an internal solution based on environment variables responded to a concrete need: operational simplicity today, strategic flexibility tomorrow.

Technical development: from culture to implementation

Trunk-Based Development as a discipline Trunk-Based Development removes long-lived branches and forces small, daily integrations.

This generates:

• A drastic reduction in merge conflicts.
• Less friction in code reviews.
• Faster delivery velocity.
• Real continuous integration, not just declarative.

In this model, fine-grained control over what is activated in production is required. Without flags, trunk-based development becomes a risk.

Feature Flags as a safety and experimentation layer

Feature Flags enable:

• Deploy without activating.
• Gradual feature enablement.
• Running A/B tests.
• Restricting access by user segments.
• Separating deployment from release.

In the backend, their implementation must be:

• Deterministic.
• Observable.
• Simple to audit.
• Easy to revert.

For that reason, we opted for an implementation compatible with OpenFeature, enabling standardization and future migration to external solutions if necessary. Designing open standards is not a tactical choice it's an architectural one.

Governance and sustainability: avoiding silent debt

The real problem with Feature Flags is not technical, it's operational. Over time they tend to:

• Accumulate.
• Be forgotten.
• Remain active unnecessarily.
• Create logical paths that are hard to maintain.

Without discipline, the system degrades. To avoid this, a clear policy was introduced:

• Mandatory documentation in comments (where, status, note, expire).
• Classification by states: Active, Development, Disabled.
• Definition of an expiration date.
• Automated weekly report sent to Slack before sprint planning.

We developed a Flag Reporter that:

• Analyzes the code.
• Extracts metadata from comments.
• Detects expired flags.
• Reports accumulation by state.
• Generates actionable alerts.

This is not just automation; it’s introducing observability and governance into the development cycle, because in mature systems quality depends not only on the code, but on how its evolution is controlled.

Recommendations

• Design your flag system before adopting trunk-based development.
• Use open standards to reduce future risks.
• Document each flag with context and an expiration date.
• Automate detection of obsolete flags.
• Include flag review in your sprint planning ritual.

Conclusions

Feature Flags are not merely conditionals in code, they are a strategic control layer within the delivery cycle. Adopting Trunk-Based Development without disciplined flag management is opening the door to invisible incidents. Implementing it with open standards, automation, and governance turns continuous integration into a real advantage. Speed without control creates debt. Speed with architecture creates competitive advantage.

Glossary

• Trunk-Based Development: A development model where everyone integrates changes frequently into the main branch.
• Feature Flag: A mechanism to enable or disable features via a condition in the code.
• OpenFeature: An open specification that standardizes Feature Flags implementation.
• FFaaS: Feature Flags as a Service — external platforms for managing flags.
• Vendor lock-in: Technological dependence that makes it difficult to change providers.