Feature Toggle

Kind: mechanism

Layer: Extensibility Core

Aliases: Feature Flag

Record: architecture:feature-toggle

Severity: contextual

Scope: application, release, runtime

Canonical: Ontology

A mechanism that switches a code path on or off at runtime from externally held flag state, so a release can happen without a deploy.

Listed in Architecture principles, after Service Locator Pattern and before Self-Healing Architecture.

Requires

• Externalized Flag State

Reinforces

• Continuous Delivery
• Runtime Extensibility

Enables

• Decoupled Deploy and Release
• Gradual Rollout

Conflicts with

• Hardcoded Branch Constant

In tension with

• Flag Debt

Tensions

• Feature Toggle / Flag Debt

Violated by

• Hardcoded Branch Constant

Severity

• contextual

Category

• Plugin / Extensibility / IoC

Refactors

• Big-Bang Release
• Attack Surface Reduction

Linked from

• A system is a graph
• Anti-patterns
• Runtime Discovery / Dynamic Binding
• Security / Privacy / Compliance / Governance
• Plugin / Extensibility / IoC
• Severity levels
• The resolutions