A Controller manages the state of a single Resource (Application, Infrastructure, or Network Resource). It participates in the Resource's instantiation and is the primary player in ongoing management, e.g. control loop actions, Resource migration/scaling, configuration, and management. Each Controller instance supports some form of orchestration to manage operations within its scope.
Infrastructure Controllers
Infrastructure Controllers typically execute OpenStack requests for the creation of virtual machines (VMs), and load the Virtual Function (VF) software into the new VM container. To do this, the Infrastructure Controller may obtain the Virtual Function's Resource recipe from the ASDC. The Resource recipe will define VM sizing, including compute, storage, and memory. When the Infrastructure Controller completes the request, it will pass the virtual resource identifier and access (IP) information back to the MSO to provide to the Network and Application controllers.
If the Resource Recipe requires multiple VMs, the MSO will repeat the process, requesting each Infrastructure Controller to spin up one or more VMs and load the appropriate VFs.
An Infrastructure Controller also has its own Recipe...?
Note that the actions of an Infrastructure Controller constitute low-level "orchestration", done outside the MSO.
Network Resource Controllers
To define a Network Resource controller, see VNF Onboarding.