Appendix A: Glossary

TermDefinition
Spot InstanceAWS EC2 instance using spare capacity at discounted prices
Preemptible VMGCP VM that can be terminated by Google at any time
Spot VMAzure VM using spare capacity at discounted prices
Durable ObjectCloudflare’s stateful serverless compute primitive
KiveraCloud security proxy that enforces policies on cloud API requests
ArbitrageTaking advantage of price differences across markets/providers
WorkloadA customer’s running application or job on spot infrastructure
PlacementThe decision of which provider, region, and instance type to use
InterruptionWhen a cloud provider reclaims a spot/preemptible instance
Health CheckPeriodic verification that a workload instance is responsive
RoutingDirecting user traffic to the correct workload instance
D1Cloudflare’s serverless SQL database
KVCloudflare’s globally distributed key-value store
WorkersCloudflare’s serverless JavaScript/TypeScript execution environment
SpectrumCloudflare’s TCP/UDP proxy service
WorkflowsCloudflare’s durable execution engine for long-running tasks