Cloud computing is an attractive model for deploying web services in a highly scalable manner. Users access such cloud-hosted services via their web-facing application programming interfaces (APIs). Prior work has shown that it is possible to use a combined approach of static analysis and cloud platform monitoring to predict the response time upper bounds of such web APIs. This technique can be employed to automatically generate service level agreements (SLAs) concerning the performance of

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... -hosted web APIs. In this work, we explore the validity period of auto-generated SLAs in cloud settings. We discuss a simple model by which API consumers can establish a response time SLA with the cloud platform, and renegotiate it when/if the SLA becomes invalid due to the dynamic nature of the cloud. Using empirical methods and simulations on a real world public cloud platform, we show that it is possible to auto-generate highly durable response time SLAs for cloud-hosted web APIs, thereby keeping the number of SLA invalidations and renegotiations very low, over long periods.