# Graceful Degradation

> A design rule that the failure of an optional dependency removes only the feature it serves, and the rest of the system keeps working.

Record: `architecture:graceful-degradation`
Kind: principle
Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md)
Severity: recommended
Scope: service, UX, system
Canonical: https://banes-lab.com/ontology#architecture-graceful-degradation

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Fail Secure](https://banes-lab.com/records/architecture/fail-secure.md) and before [Fault Tolerance](https://banes-lab.com/records/architecture/fault-tolerance.md).

## Repair

- Refactored by: Add Fallback, Isolate Optional Dependency
- Detected by: critical path dependency on optional service
- Violated by: total outage from noncritical dependency failure
- Measured by: partial availability under failure
- Enforced by: chaos tests

## Requires

- [Fallback](https://banes-lab.com/records/lexicon/fallback.md)
- [Feature Isolation](https://banes-lab.com/records/lexicon/feature-isolation.md)

## Reinforces

- [Fault Tolerance](https://banes-lab.com/records/architecture/fault-tolerance.md)

## Enables

- [Partial Availability](https://banes-lab.com/records/lexicon/partial-availability.md)

## Conflicts with

- [All-Or-Nothing Failure](https://banes-lab.com/records/lexicon/all-or-nothing-failure.md)

## In tension with

- [Consistency / Feature Completeness](https://banes-lab.com/records/lexicon/consistency-feature-completeness.md)
- [Fail Fast](https://banes-lab.com/records/architecture/fail-fast.md)
- [Fail Fast / Graceful Degradation](https://banes-lab.com/records/tension/fail-fast-graceful-degradation.md)

## Tensions

- [Graceful Degradation / Consistency / Feature Completeness](https://banes-lab.com/records/tension/consistency-feature-completeness-graceful-degradation.md)

## Severity

- [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md)

## Category

- [Error Handling / Resilience](https://banes-lab.com/records/architecture-category/error-handling-resilience.md)

## Reinforced by

- [Fallback Pattern](https://banes-lab.com/records/architecture/fallback-pattern.md)

## Linked from

- [Fail at the boundary](https://banes-lab.com/disciplined-methodology/build/fail-at-the-boundary.md)
- [Separate, trade, or mitigate](https://banes-lab.com/software-architecture/principles/separate-trade-or-mitigate.md)
- [Error Handling / Resilience](https://banes-lab.com/ontology/principles/architecture-category-error-handling-resilience.md)
- [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lexicon-category-core-vocabulary.md)
- [Error Handling / Resilience](https://banes-lab.com/ontology/lexicon/lexicon-category-error-handling-resilience.md)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)