inject

Inject interface table

interface name	required func	func to inject	Implemented by
Cache	InjectCache	CacheInto	Kind (source)
APIReader	InjectAPIReader	APIReaderInto
Config	InjectConfig	ConfigInto
Client	InjectClient	ClientInto
Scheme	InjectScheme	SchemeInto	DeferredFileLoader, Webhook
Stoppable	InjectStopChannel	StopChannelInto	Channel (source)
Mapper	InjectMapper	MapperInto	EnqueueRequestForOwner
Injector	InjectFunc	InjectorInto	Webhook, enqueueRequestsFromMapFunc, Controller, and, or (predicate), multiMutating, multiValidating, etc.
Logger	InjectLogger	LoggerInto	Webhook

Injector interface

// Func injects dependencies into i.
type Func func(i interface{}) error

// Injector is used by the ControllerManager to inject Func into Controllers.
type Injector interface {
    InjectFunc(f Func) error
}

// InjectorInto will set f and return the result on i if it implements Injector.  Returns
// false if i does not implement Injector.
func InjectorInto(f Func, i interface{}) (bool, error) {
    if ii, ok := i.(Injector); ok {
        return true, ii.InjectFunc(f)
    }
    return false, nil
}

SetFields set dependencies to the object that implments inject interface.

Usage

Controller implement Injector with InjectFunc

// InjectFunc implement SetFields.Injector.
func (c *Controller) InjectFunc(f inject.Func) error {
    c.SetFields = f
    return nil
}

With this implementation, any function can be injected to the controller.SetFields with InjectorInto(func, controller).

This function is used in the manager.SetFields

if _, err := inject.InjectorInto(cm.SetFields, i); err != nil {

This means set clusterManager's SetFields function to i, specifically, controller. By the controller's InjectFunc implementation, controller has exactly the same SetFields function as clusterManager