Currently, the LinuxLauncher looks into SlaveFlags to compute the namespaces that should be enabled when launching the executor. This means that a custom Isolator module doesn't have any way to specify dependency on a set of namespaces.
The proposed solution is to extend the Isolator interface to also export the namespaces dependency. This way the MesosContainerizer can directly query all loaded Isolators (inbuilt and custom modules) to compute the set of namespaces required by the executor. This set of namespaces is then passed on to the LinuxLauncher.