How to fix error with AWS Lambda handler, DynamoDB Put req?

Question

Trying to create a Lambda to interact with my DynamoDB. This specific Lambda is to put/write an item to the DB:

package main

import (
    "fmt"

    "github.com/aws/aws-lambda-go/lambda"
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/dynamodb"
    "github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
)

type Item struct {
    Email    string `json:"email"`
    Password string `json:"password"`
    Rname    string `json:"rname"`
}

func Put() error {

    // Create a session - London Region
    session, err := session.NewSession(&aws.Config{
        Region: aws.String("eu-west-2")},
    )
    if err != nil {
        fmt.Println(err)
    }

    svc := dynamodb.New(session)

    // Create instance of Item Struct
    item := Item{
        Email:    "[email protected]",
        Password: "12345678",
        Rname:    "abcde",
    }

    // Marshall Item
    av, err := dynamodbattribute.MarshalMap(item)

    if err != nil {
        fmt.Println("Got error marshalling map:")
        fmt.Println(err)
    }

    // Create Item
    input := &dynamodb.PutItemInput{
        Item:      av,
        TableName: aws.String("accountsTable"),
    }

    _, err = svc.PutItem(input)

    if err != nil {
        fmt.Println("Got error calling PutItem:")
        fmt.Println(err)
    }
    return err
}

func main() {
    lambda.Start(Put())
}

However getting the error:

{
  "errorMessage": "handler is nil",
  "errorType": "errorString"
}

I have changed the handler in run time settings to main too so don't think that would be the issue.

Building with:

GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -a main.go

and putting the zip of the executable into AWS via console (no IAC's)

Any help would be greatly appreciated to resolve this error! Thanks.

Have you tried to execute an empty Lambda function without the logic? — Leeroy Hannigan
– Leeroy Hannigan, Commented Dec 29, 2022 at 19:34
I'm not sure what you mean, just like a simple hello world to print? — HBridges
– HBridges, Commented Dec 29, 2022 at 19:34
Exactly, just to rule out if the error is from the function setup or from custom logic. — Leeroy Hannigan
– Leeroy Hannigan, Commented Dec 29, 2022 at 19:42
just tried and got a failure just trying to print out hello, the function that main calls returning the same hello string. Fails on "handler kind string is not func" — HBridges
– HBridges, Commented Dec 29, 2022 at 19:45

Mehmet Güngören · Accepted Answer · 2022-12-29 19:52:17Z

1

You need to pass function handle not function result to lambda.Start

Please update your main function with👇

func main() {
    lambda.Start(Put)
}

answered Dec 29, 2022 at 19:52

Mehmet Güngören

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1 Comment

HBridges Over a year ago

Thank you - just realised this before I came back to here! Silly one to be stuck on for so long haha

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