Execution failed due to configuration error: Invalid permissions on Lambda function

Question

I am building a serverless application using AWS Lambda and API Gateway via Visual Studio. I am working in C#, and using the serverless application model (SAM) in order to deploy my API. I build the code in Visual Studio, then deploy via publish to Lambda. This is working, except every time I do a new build, and try to execute an API call, I get this error:

Execution failed due to configuration error: Invalid permissions on Lambda function

Doing some research, I found this fix mentioned elsewhere (to be done via the AWS Console):

Fix: went to API Gateway > API name > Resources > Resource name > Method > Integration Request > Lambda Function and reselected my existing function, before "saving" it with the little checkmark.

Now this works for me, but it breaks the automation of using the serverless.template (JSON) to build out my API. Does anyone know how to fix this within the serverless.template file? So that I don't need to take action in the console to resolve? Here's a sample of one of my methods from the serverless.template file

{
  "AWSTemplateFormatVersion" : "2010-09-09",
  "Transform" : "AWS::Serverless-2016-10-31",
  "Description" : "An AWS Serverless Application.",

  "Resources" : {

    "Get" : {
      "Type" : "AWS::Serverless::Function",
      "Properties": {
        "VpcConfig":{
          "SecurityGroupIds" : ["sg-111a1476"],
          "SubnetIds" : [ "subnet-3029a769","subnet-5ec0b928"]
        },
        "Handler": "AWSServerlessInSiteDataGw::AWSServerlessInSiteDataGw.Functions::Get",
        "Runtime": "dotnetcore2.0",
        "CodeUri": "",
        "MemorySize": 256,
        "Timeout": 30,
        "Role": null,
        "Policies": [ "AWSLambdaBasicExecutionRole","AWSLambdaVPCAccessExecutionRole","AmazonSSMFullAccess"],
        "Events": {
          "PutResource": {
            "Type": "Api",
            "Properties": {
              "Path": "/",
              "Method": "GET"
            }
          }
        }
      }
    },

Answer 1

You may have an issue in permission config, that's why API couldn't call your lambda. try to explicitly add to template.yaml file invoke permission to your lambda from apigateway as a principal here's a sample below:

  ConfigLambdaPermission:
    Type: "AWS::Lambda::Permission"
    DependsOn:
    - MyApiName
    - MyLambdaFunctionName
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !Ref MyLambdaFunctionName
      Principal: apigateway.amazonaws.com

Here's the issue that was reported in SAM github repo for complete reference and here is an example of hello SAM project

If you would like to add permission by AWS CLI for testing things out, you may want to use aws lambda add-permission. please visit official documentation website for more details.

Answer 2

I had a similar issue - I deleted then re-installed a lambda function. My API Gateway was still pointing at the old one, so I had to go into the API Gateway and change my Resource Methods to alter the Integration Request setting to point to the new one (it may look like it's pointing to the correct one but wasn't in my case)

Answer 3

I was having the same issue but I was deploying through Terraform. After a suggestion from another user, I reselected my Lambda function in the Integration part of the API Gateway, and then checked what changed in my Lambda permissions. Turns out I needed to add a "*" where I was putting the stage name in the source_arn section of the API Gateway trigger in my Lambda resource. Not sure how SAM compares to Terraform but perhaps you can change the stage name or just try this troubleshooting technique that I tried.

My SO posting: AWS API Gateway and Lambda function deployed through terraform -- Execution failed due to configuration error: Invalid permissions on Lambda function

Answer 4

Same error, and the solution was simple: clearing and applying the "Lambda Function" mapping again in the integration setting of the API Gateway.

My mapping looks like this: MyFunction-894AR653OJX:test where "test" is the alias to point to the right version of my lambda

The problem was caused by removing the ALIAS "test" on the lambda, and recreating it on another version (after publishing). It seems that the API gateway internally still links to the `old' ALIAS instance. You would expect that the match is purely done on name...

Bonus: so, via the AWS console you cannot move that ALIAS, but you can do this via the AWS CLI, using the following command:

aws lambda --profile <YOUR_PROFILE> update-alias --function-name <FUNCTION_NAME> --name <ALIAS_NAME> --function-version <VERSION_NUMBER>

Answer 5

I had the same issue. I changed the integration to mock first, i.e unsetting the integration type to Lambda, and then after one deployment, set the integration type to lambda again. It worked flawlessly thereafter.

I hope it helps.

Answer 6

Facing the same issue, I figured out the problem is : API Gateway is not able to invoke the Lambda function as I couldn't see any CloudWatch logs for the lambda Function.

So firstly I went through API Gateway console and under the Integration Request - gave the full ARN for the Lambda Function. and it is started working.

Secondly, through the CloudFormation

x-amazon-apigateway-integration:
        credentials:
          Fn::Sub: "${ApiGatewayLambdaRole.Arn}"
        type: "aws"
        uri:
          Fn::Sub: "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${lambda_function.Arn}/invocations"

Answer 7

I had the same problem so I deleted then created the stack and it worked.

Answer 8

I had a similar problem and was using Terraform. It needed the policy with the "POST" in it. For some reason the /*/ (wildcard) policy didn't work?

Here's the policy and the example terraform I used to solve the issue.

Many thanks to all above.

Here is what my Lambda function policy JSON looked like and the terraform:

    {
      "Version": "2012-10-17",
      "Id": "default",
      "Statement": [
        {
          "Sid": "AllowAPIGatewayInvoke",
          "Effect": "Allow",
          "Principal": {
            "Service": "apigateway.amazonaws.com"
          },
          "Action": "lambda:InvokeFunction",
          "Resource": "arn:aws:lambda:us-east-1:999999999999:function:MY-APP",
          "Condition": {
            "ArnLike": {
              "AWS:SourceArn": "arn:aws:execute-api:us-east-1:999999999999:d85kyq3jx3/test/*/MY-APP"
            }
          }
        },
        {
          "Sid": "e841fc76-c755-43b5-bd2c-53edf052cb3e",
          "Effect": "Allow",
          "Principal": {
            "Service": "apigateway.amazonaws.com"
          },
          "Action": "lambda:InvokeFunction",
          "Resource": "arn:aws:lambda:us-east-1:999999999999:function:MY-APP",
          "Condition": {
            "ArnLike": {
              "AWS:SourceArn": "arn:aws:execute-api:us-east-1:999999999999:d85kyq3jx3/*/POST/MY-APP"
            }
          }
        }
      ]
    }

    add in a terraform like this:


    //************************************************
    // allows you to read in the ARN and parse out needed info, like region, and account
    //************************************************
    data "aws_arn" "api_gw_deployment_arn" {
        arn = aws_api_gateway_deployment.MY-APP_deployment.execution_arn 
    }

    //************************************************
    // Add in this to support API GW testing in AWS Console.
    //************************************************
    resource "aws_lambda_permission" "apigw-post" {
        statement_id  = "AllowAPIGatewayInvokePOST"
        action        = "lambda:InvokeFunction"
        //function_name = aws_lambda_function.lambda-MY-APP.arn
        function_name = module.lambda.function_name
        principal     = "apigateway.amazonaws.com"

        // "arn:aws:execute-api:us-east-1:473097069755:708lig5xuc/dev/POST1/cloudability-church-ws"
        source_arn = "arn:aws:execute-api:${data.aws_arn.api_gw_deployment_arn.region}:${data.aws_arn.api_gw_deployment_arn.account}:${aws_api_gateway_deployment.MY-APP_deployment.rest_api_id}/*/POST/${var.api_gateway_root_path}"
    }

Answer 9

The documentation for AWS lambda resource permissions shows 3 levels of access you can filter or wildcard, /*/*/*, which is documented as $stage/$method/$path. However, their example and most examples online only use 2 levels and I was bashing my head against the wall using 3 only to get Access Denied. I changed down to 2 levels and lambda then created the trigger. Hopefully, this will save someone from throwing their computer against the wall.