AWS Lambda GoLang处理程序API

Question

Is it possible to implement Lambda function handler with custom API?

For aws-lambda-go the valid handler is one of following types:

//  func ()
//  func () error
//  func (TIn) error
//  func () (TOut, error)
//  func (TIn) (TOut, error)
//  func (context.Context) error
//  func (context.Context, TIn) error
//  func (context.Context) (TOut, error)
//  func (context.Context, TIn) (TOut, error)

In my case, TIn is KinesisEvent containing MySpecificType as a payload. I'm looking for the way (maybe to overwrite lambda.Start()) to be able to create the handler of type

func(MySpecificType) error

The goal is to avoid extracting the payload from KinesisEvent in every lambda and make the handler source independent

Answer 1

Seems like the solution is quite simple. Just overwrite the lambda.Start() method:

func Start(handler func(t * MySpecificType, i int) error) {

    lambda.Start(func(kinesisEvent events.KinesisEvent) (err error) {

        for i, record := range kinesisEvent.Records {

            mySpecType := new(MySpecificType)
            if err = json.Unmarshal(record.Kinesis.Data, mySpecType); err != nil {
                logrus.Errorf("records[%d]: %s", i, err)
                continue
            }

            err = handler(mySpecType, i)
        }
        return
    })
}

and then:

// main.go
func Handler(m *MySpecificType, index int) error {
// ...
}

func main() {
    <wherever_you_put_it_package>.Start(Handler)
    // instead of lambda.Start(Handler)
}