Add controller to the manager dynamically at runtime

[clyang82]

I have a use case is:

1. the CRD does not exist in the runtime environment at the beginning.
2. if the users create this CRD and CR, I want to start a controller to watch the CR for reconciling.

for this case, I cannot add this controller to the manager before the manager starts, because the CRD does not exist. so I want to watch the CustomResourceDefinitions to see if my desired CRD is created and the CR is also created, then I want to dynamically start a controller to watch this CR. Is it possible to add a controller to the manager when the manager is running? or How can I start the controller manually? I saw the controller is not exposed -

controller-runtime/pkg/builder/controller.go

Line 331 in 15b6689

blder.ctrl, err = newController(controllerName, blder.mgr, ctrlOptions)

Thanks.

[clyang82]

@DirectXMan12 any insights or best practices can be shared? Thanks.

[FillZpp]

Is it possible to add a controller to the manager when the manager is running?

Yes.

How can I start the controller manually?

Same as the normal ones:

func (r *YourDynamicController) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&groupversion.Foo{}).
		Complete(r)
}

[clyang82]

Yes. It works. Thanks @FillZpp