type Delta struct {
	// Name of the setting being changed.
	Name string

	// FromValue is the value of the setting before applying the delta.
	FromValue string

	// ToValue is the value of the setting after applying the delta.
	ToValue string

	// Mandatory indicates whether the delta *must* be applied.
	// This should be set in cases where `runsc` will fail completely
	// if the delta is not applied.
	Mandatory bool

	// Purpose achieved by applying the delta.
	Purpose string

	// Apply applies the delta.
	Apply func() error
}

type Setting interface {
	// Name is the name of the setting. In most cases this should be the
	// full path of the setting, either under /sys or /proc/sys.
	// This can be a non-path for settings that are not controlled via files,
	// such as kernel command-line parameters or SELinux labels.
	Name() string

	// Delta checks whether the current value of the setting is optimal.
	// If already optimal, it returns a nil Delta.
	Delta() (*Delta, error)
}