Istio Manager is used to configure Istio and propagate configuration to the other components of the system, including the Istio mixer and the Istio proxies.
If you have a question about the Istio Manager or have a problem using it, please file an issue.
Istio Manager design gives an architectural overview of the manager components - cluster platform abstractions, service model, and the proxy controllers.
If you are interested in contributing to the project, please take a look at the build instructions and the testing infrastructure.