Gradual rollout management for client applications
It sounds like you are talking about Canary Analysis ? If so, Spinnaker has deployment based on  canary analysis built on, using metrics provided by the application telemetry. To quote the Spinnaker docs:

Your application might send performance metrics which are published and available by default. You can also install a monitoring agent to collect more comprehensive metrics, and you can instrument your code to generate further metrics for that agent. In any case, you need to have access to a set of metrics, using some telemetry provider, which Kayenta can then use to make the canary judgment.
Support is built in for Stackdriver, Datadog, Prometheus, Signalfx, and New Relic.

So, you use Spinnaker as a continuous deployment service and instrument the application with one of the supported mechanisms. Canary analysis can then be done to manage the roll-out of new version.