AccessDeniedException: Unable to determine service/operation name to be authorized

Question

Using AWS CLI

aws --version
aws-cli/1.11.21 Python/2.7.12 Darwin/15.3.0 botocore/1.4.78

Creating a POST method for API Gateway as explained at https://github.com/arun-gupta/serverless/tree/master/aws/microservice#post-method. This method can be invoked successfully using test-invoke-method and AWS Console.

Creating a GET method using AWS CLI https://github.com/arun-gupta/serverless/tree/master/aws/microservice#get-method. Invoking this method using test-invoke-method and AWS Console gives the following error:

{
    "status": 500,
    "body": "{\"message\": \"Internal server error\"}",
    "log": "Execution log for request test-request\nThu Dec 29 00:58:56 UTC 2016 : Starting execution for request: test-invoke-request\nThu Dec 29 00:58:56 UTC 2016 : HTTP Method: GET, Resource Path: /books\nThu Dec 29 00:58:56 UTC 2016 : Method request path: {}\nThu Dec 29 00:58:56 UTC 2016 : Method request query string: {}\nThu Dec 29 00:58:56 UTC 2016 : Method request headers: {}\nThu Dec 29 00:58:56 UTC 2016 : Method request body before transformations: \nThu Dec 29 00:58:56 UTC 2016 : Endpoint request URI: https://lambda.us-west-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-west-1:598307997273:function:MicroserviceGetAll/invocations\nThu Dec 29 00:58:56 UTC 2016 : Endpoint request headers: {x-amzn-lambda-integration-tag=test-request, Authorization=******************************************************************************************************************************************************************************************************************************************************************************************************482377, X-Amz-Date=20161229T005856Z, x-amzn-apigateway-api-id=sofl9ilki7, X-Amz-Source-Arn=arn:aws:execute-api:us-west-1:598307997273:sofl9ilki7/null/GET/books, Accept=application/json, User-Agent=AmazonAPIGateway_sofl9ilki7, Host=lambda.us-west-1.amazonaws.com, X-Amzn-Trace-Id=Root=1-58645fd0-7d733ae3c383f4378fcc0338}\nThu Dec 29 00:58:56 UTC 2016 : Endpoint request body after transformations: \nThu Dec 29 00:58:56 UTC 2016 : Endpoint response body before transformations: <AccessDeniedException>\n  <Message>Unable to determine service/operation name to be authorized</Message>\n</AccessDeniedException>\n\nThu Dec 29 00:58:56 UTC 2016 : Endpoint response headers: {x-amzn-RequestId=f95a8659-cd61-11e6-80f6-ddd6ce5b7e8b, Connection=keep-alive, Content-Length=130, Date=Thu, 29 Dec 2016 00:58:56 GMT}\nThu Dec 29 00:58:56 UTC 2016 : Lambda invocation failed with status: 403\nThu Dec 29 00:58:56 UTC 2016 : Execution failed due to configuration error: \nThu Dec 29 00:58:56 UTC 2016 : Method completed with status: 500\n",
    "latency": 39
}

The ARN identified in the error message is arn:aws:execute-api:us-west-1:598307997273:sofl9ilki7/null/GET/books. Wondering if null instead of test is causing this to fail?

Answer 1

I think you are using "GET" for your Lambda function endpoint on your GET method as well. Please change it to use "POST" for the Lambda integration HTTP method.

Answer 2

To invoke a lambda function the http method should be POST as per the lambda API:

Visit http://docs.aws.amazon.com/lambda/latest/dg/API_Invoke.html.