  Hybrid cloud provides an attractive solution to microservices for better
resource elasticity. A subset of application components can be offloaded from
the on-premises cluster to the cloud, where they can readily access additional
resources. However, the selection of this subset is challenging because of the
large number of possible combinations. A poor choice degrades the application
performance, disrupts the critical services, and increases the cost to the
extent of making the use of hybrid cloud unviable. This paper presents Atlas, a
hybrid cloud migration advisor. Atlas uses a data-driven approach to learn how
each user-facing API utilizes different components and their network footprints
to drive the migration decision. It learns to accelerate the discovery of
high-quality migration plans from millions and offers recommendations with
customizable trade-offs among three quality indicators: end-to-end latency of
user-facing APIs representing application performance, service availability,
and cloud hosting costs. Atlas continuously monitors the application even after
the migration for proactive recommendations. Our evaluation shows that Atlas
can achieve 21% better API performance (latency) and 11% cheaper cost with less
service disruption than widely used solutions.
