Dynamic resource scaling is a key property of cloud
computing. Users can acquire or release required capacity for
their applications on-the-fly. The most widely used and practical
approach for dynamic scaling based on predefined policies (rules).
For example, IaaS providers such as RightScale asks application
owners to manually set the scaling rules. This task assumes, that
the user has an expertise knowledge about the application being
run on the cloud. However, it is not always true. In this paper
we propose a lightweight adaptive multi-tier scaling framework
VscalerLight, which learns scaling policy online. Our framework
performs fine-grained vertical resource scaling of multi-tier
web application. We present the design and implementation of
VscalerLight. We evaluate the framework against widely used
RUBiS benchmark. Results show that the application under
control of VscalerLight guarantees 95th percentile response time
specified in SLA.