aws-api-gateway-to-sns.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS Api Gateway to SNS topic  

Resources:

  StatsApiGateway:
    Type: AWS::Serverless::Api
    Properties:
      StageName: Prod
      DefinitionBody:
        swagger: "2.0"
        info:
          version: "v1"
          title: !Ref AWS::StackName
        paths:
          /stats:
            post:
              responses:
                "202":
                  description: Accepted
              x-amazon-apigateway-integration:
                type: "aws"
                httpMethod: "POST"
                uri: !Sub "arn:aws:apigateway:${AWS::Region}:sns:action/Publish"
                credentials: !GetAtt StatsApiRole.Arn
                requestParameters:
                  integration.request.querystring.Message: "method.request.body"
                  integration.request.querystring.TopicArn: !Sub "'${StatsTopic}'"
                responses:
                  default:
                    statusCode: 202

  StatsApiRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "apigateway.amazonaws.com"
            Action:
              - "sts:AssumeRole"
      Policies:
        - PolicyName: !Sub "${AWS::StackName}-topic-policy"
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Action: "sns:Publish"
                Effect: "Allow"
                Resource: !Ref StatsTopic
      ManagedPolicyArns:
        - "arn:aws:iam::aws:policy/service-role/AmazonAPIGatewayPushToCloudWatchLogs"
        
  StatsTopic:
    Type: AWS::SNS::Topic