Most large web-scale applications are now built by composing collections (up to 100s or 1000s) of microservices. Operators need to decide how many resources are allocated to each microservice, and these allocations can have a large impact on application performance. Manually determining allocations that are both cost-efficient and meet performance requirements is challenging, even for experienced operators. In this paper we present Autotune, an end-to-end tool that automatically minimizes resource utilization while maintaining good application performance.