message: "Internal server error" when try to access aws gateway api

Question

Created Lambda Hello world function using Node.js and created API GateWay trigger for Get call, tried the URL to access Lambda function, getting below error.

message: "Internal server error".

(very new to AWS)

Answer 1

You need to pass the statusCode after executing the Lambda function. If you don't pass it the API Gateway will trigger an error 502 Bad Gateway by default.

message = {
   'message': 'Execution started successfully!'
}
return {
    'statusCode': 200,
    'headers': {'Content-Type': 'application/json'},
    'body': json.dumps(message)
}

EDIT: This sample is for Python. For node.js you just need to handle callback, the message is basically the same.

callback(null, {
    statusCode: 200,
    body: JSON.stringify(message),
    headers: {'Content-Type': 'application/json'}
});

Answer 2

Don't forget to click Deploy API under AWS API Gateway. Without it, change doesn't work.

Answer 3

For accessing dynamodb through lambda function from api gateway it needs:

1. Create a role in AWS console that have access to dynamodb operations.

2. Create a lambda function and assign the above created role to your lambda function.

3. Create a api from API gateway in AWS management console and allow it to access to your lambda function.

4. In order for your api to show a proper response the return type of lambda function should be a specific format i.e :

return {
  "statusCode": 200,
  "body": json.dumps(your response)
}