Passing AWS region and account ID to swagger

Question

I am defining my API Gateway APIs using AWS SAM

ApiGatewayApi:
  Type: AWS::Serverless::Api
  Properties:
    DefinitionUri: swagger.yml
    StageName: prod
    Variables:
      Region: !Ref AWS::Region
      AccountId: !Ref AWS::AccountId
      Ec2Index: !Ref Ec2Index
      AuthLogin: !Ref AuthLogin
      Ec2Patch: !Ref Ec2Patch
      AutoScalingIndex: !Ref AutoScalingIndex
      AutoScalingPatch: !Ref AutoScalingPatch
      AutoScalingScale: !Ref AutoScalingScale

In my swagger file:

paths: /auth/session: post: produces: - application/json x-amazon-apigateway-integration: uri: arn:aws:apigateway:ap-southeast-1:lambda:path/2015-03-31/functions/arn:aws:lambda:ap-southeast-1:598545985414:function:${stageVariables.AuthLogin}/invocations passthroughBehavior: when_no_match httpMethod: POST type: aws_proxy responses: 200: description: App token 401: description: 401 403: description: 403

AWS CloudFormation errors saying

Errors found during import: Unable to put integration on 'POST' for resource at path '/auth/session': Lambda function ARN must be in same account Unable to put integration on 'GET' for resource at path '/autoscaling': Lambda function ARN must be in same account Unable to put integration on 'PATCH' for resource at path '/autoscaling/{groupName}': Lambda function ARN must be in same account Unable to put integration on 'POST' for resource at path '/autoscaling/{groupName}/scale': Lambda function ARN must be in same account Unable to put integration on 'GET' for resource at path '/ec2': Lambda function ARN must be in same account Unable to put integration on 'PATCH' for resource at path '/ec2/{id}': Lambda function ARN must be in same account

Seems like my ARN is invalid. This is resolved once I remove the variables. Whats wrong here?

Stephen Brickner Stephen Brickner · Accepted Answer · 2017-10-17T10:19:31

As of now swagger does not allow AccountId in stage variables. It's a limitation of the API Gateway.

You can get around this by just using a stage variable for the function name only and piece the rest together like this:

//does not get passed in. This is just a placeholder for the stage variable
Parameters: 
    ApiFunctionName:
        Type: String
        Description: Function name of the api lambda function
        Default: ${stageVariables.yourFunctionNameVar}

//in your gateway path   
    x-amazon-apigateway-integration:
        httpMethod: POST
        type: aws_proxy
        uri: 
          !Sub "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:${ApiFunctionName}/invocations"

Passing AWS region and account ID to swagger

2 Answers