Cloudformation custom resource template

Usage example

Cloudformation resource definition

Define service token (lambda arn) and input properties

MyCustomResource:
 Type: Custom::MyCustomResource
 Version: "1.0"
 Properties:
   ServiceToken: <lambda_arn>
   Property1: "test1"
   Property2: "test2"

Handler implementation

Pass struct that implements model.ResourceProperties interface as a second parameter

func Handle(evt *cloudformationevt.Event, runtimeCtx *runtime.Context) (interface{}, error) {
	return customresource.Execute(evt, MyResourceProperties{})
}

Resource properties interface implementation

Properties

Define properties as in cloudformation

type MyResourceProperties struct {
	Property1 string
	Property2 string
}

Validate()

Validate required fields and other data if necessary

func (data MyResourceProperties) Validate() error {
	if data.Property1 == "" {
		return errors.New("Property1 must be set")
	}
	return nil
}

Create()

• Action on resource create
• It must always return non-null physical resource ID
• If error is not nil it will return as FAILED, otherwise SUCCESS

func (data MyResourceProperties) Create() (string, error) {
  //create logic
	return "<physicalResourceId>", nil
}

Update()

• Action on resource update
• It must always return non-null physical resource ID
• If ID is changed, cloudformation will invoke recreate action
• If error is not nil it will return as FAILED, otherwise SUCCESS

func (data MyResourceProperties) Update() (string, error) {
  //update logic
	return "<physicalResourceId>", nil
}

Delete()

• Action on resource delete
• If error is not nil it will return as FAILED, otherwise SUCCESS

func (data MyResourceProperties) Delete() error {
  //delete logic
	return nil
}

GetInstance()

Helper method to allow json unmarshalling

func (data MyResourceProperties) GetInstance() interface{} {
	return &MyResourceProperties{}
}