GoLang AWS Lambda Function Missing Body from API Gateway Request

Question

I'm using an AWS Lambda function to handle a request from an AWS API Gateway call. I'm sending a payload on the request, and I can verify in CloudWatch that the payload is being passed from the gateway to the lambda function. However, the body of the request is null inside my Lambda function.

I looked at this question: AWS Lambda Go function not getting request body when called via API GW

I am trying to replicate the answer there by using this library: https://github.com/aws/aws-lambda-go/blob/master/events/apigw.go, but I'm still not able to get the request body.

Here is my Lambda code:

package main

import (
    "context"
    "fmt"

    "github.com/aws/aws-lambda-go/events"
    "github.com/aws/aws-lambda-go/lambda"
)

func handleRequest(ctx context.Context, request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {

    fmt.Println("Body")
    fmt.Println(request.Body)

    fmt.Printf("Processing request data for request %s.\n", request.RequestContext.RequestID)

    fmt.Printf("Processing request data for request %s.\n", request.RequestContext.RequestID)
    fmt.Printf("Body size = %d.\n", len(request.Body))

    fmt.Println("Headers:")
    for key, value := range request.Headers {
        fmt.Printf("    %s: %s\n", key, value)
    }

    return events.APIGatewayProxyResponse{Body: request.Body, StatusCode: 200}, nil
}

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

I'm expecting to see some data after "Body" in Cloudwatch, but there is nothing.

I guess you have mapped that lambda to an GET http call in your APIGateway and they never have a body. Try printing request.Path for example. — Jonny Rimek
@JonnyRimek, It's a POST call in my API Gateway. In Cloudwatch, the logs say: Endpoint request body after transformations: {"my": "body data"}. Then they say: Sending request to lambda.us-east-1.amazonaws.com/my-lamba-path, so I'm pretty sure the request body is being sent to the Lambda? — Ben Freed
Kind of frustrating to see my question downvoted with no comment. If there an issue with the question, please let me know in the comments. — Ben Freed
I don't see an obvious error. gitlab.com/jrimek/tnp/api/blob/master/handler/create-category/… this is a lambda that receives a POST request and writes an item to DynamoDB, maybe you see something that can help you — Jonny Rimek

Ben Freed Ben Freed · Accepted Answer · 2019-08-06T12:48:39

The code in the original question is correct. The second argument to the handleRequest is of the type APIGatewayProxyRequest. In API Gateway, I was sending a normal request, not a proxy request. I redeployed my API Gateway route as a proxy request and got the request body I was expecting. I'm still not really sure whether my original request was failing to send the body, or if the structure of a normal request passed into the handleRequest function is different from that of a proxy request and so the APIGatewayProxyRequest type was unable to parse its body.

GoLang AWS Lambda Function Missing Body from API Gateway Request

1 Answers