Interface Res

engine/resources.go:256–297

Res is the minimum interface you need to implement to define a new resource.

// Res is the minimum interface you need to implement to define a new resource.
type Res interface {
	fmt.Stringer // String() string

	KindedRes
	NamedRes // TODO: consider making this optional in the future
	MetaRes  // All resources must have meta params.

	// Default returns a struct with sane defaults for this resource.
	Default() Res

	// Validate determines if the struct has been defined in a valid state.
	Validate() error

	// Init initializes the resource and passes in some external information
	// and data from the engine.
	Init(*Init) error

	// Cleanup is run by the engine to clean up after the resource is done.
	Cleanup() error

	// Watch is run by the engine to monitor for state changes. If it
	// detects any, it notifies the engine which will usually run CheckApply
	// in response. If the input context cancels, we must shutdown.
	Watch(context.Context) error

	// CheckApply determines if the state of the resource is correct and if
	// asked to with the `apply` variable, applies the requested state. If
	// the input context cancels, we must return as quickly as possible. We
	// should never exit immediately if this would cause permanent
	// corruption of some sort. However it doesn't mean that a resource was
	// taken to the desired state. The input context is not guaranteed to
	// cancel when you return from this function. If that's required for
	// your code to free memory, make sure to wrap it, cancel it on return
	// with a defer, and wait for any workers to exit with a waitgroup.
	CheckApply(ctx context.Context, apply bool) (checkOK bool, err error)

	// Cmp compares itself to another resource and returns an error if they
	// are not equivalent. This is more strict than the Adapts method of the
	// CompatibleRes interface which allows for equivalent differences if
	// the have a compatible result in CheckApply.
	Cmp(Res) error
}

// Repr returns a representation of a resource from its kind and name. This is
// used as the definitive format so that it can be changed in one place.