our electronic trading business, it is important to thoroughly test algo behaviors. Although microservice components can easily be unit tested, it is often non-trivial to automate the system-level tests A controller layer: This layer provides a set of APIs (interfaces) to interact with the microservice system. It sets up an internal test version of the system with a collection of components, a

application release model that gradually transfers user traffic from a previous version of an app or microservice to a nearly identical new release — both of which are running in production. The old version