# Auto-Scaling

> The ability to change the number of running instances automatically, between set bounds, from a load metric.

Record: `architecture:auto-scaling`
Kind: capability
Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md)
Severity: contextual
Scope: deployment, service, infrastructure
Aliases: Demand-Based Capacity
Canonical: https://banes-lab.com/ontology#architecture-auto-scaling

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Replication](https://banes-lab.com/records/architecture/replication.md) and before [Auto-Remediation](https://banes-lab.com/records/architecture/auto-remediation.md).

## Repair

- Refactored by: Add Scaling Policy, Make Service Stateless
- Detected by: saturation under load without scale policy
- Violated by: manual-only scaling for variable load
- Measured by: scaling latency, saturation rate
- Enforced by: infrastructure-as-code policy

## Requires

- [Horizontal Scalability](https://banes-lab.com/records/lexicon/horizontal-scalability.md)
- [Metrics](https://banes-lab.com/records/lexicon/metrics.md)

## Reinforces

- [Elasticity](https://banes-lab.com/records/architecture/elasticity.md)

## In tension with

- [Cost/Cold Start](https://banes-lab.com/records/lexicon/cost-cold-start.md)
- [Fixed Capacity](https://banes-lab.com/records/lexicon/fixed-capacity.md)

## Tensions

- [Auto-Scaling / Cost/Cold Start](https://banes-lab.com/records/tension/auto-scaling-cost-cold-start.md)
- [Auto-Scaling / Fixed Capacity](https://banes-lab.com/records/tension/auto-scaling-fixed-capacity.md)

## Severity

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

## Category

- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/records/architecture-category/self-healing-recovery-deployment-safety.md)

## Enabled by

- [Statelessness](https://banes-lab.com/records/architecture/statelessness.md)

## Linked from

- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lexicon-category-core-vocabulary.md)
- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/lexicon/lexicon-category-self-healing-recovery-deployment-safety.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)