how to pass bucket/key name to fargate job via a cloudwatch event trigger on s3 object creation event?

I have create a fargate task and trying to trigger it via s3 object creation event ( see sample below) via cloudformation.as it cannot trigger it directly, i have created a cloudwatchevent. I am trying to pass the bucket and obj name to my fargate task code . doing some research, i came across -> InputTransformer, but i'm not sure how to pass the value of my bucket and key name and how to read it in my python code. any help will be appreciated.

AWSTemplateFormatVersion: 2010-09-09
Description: An example CloudFormation template for Fargate.
Parameters:
  VPC:
    Type: AWS::EC2::VPC::Id
  SubnetA:
    Type: AWS::EC2::Subnet::Id
  SubnetB:
    Type: AWS::EC2::Subnet::Id
  Image:
    Type: String
    Default: 123456789012.dkr.ecr.region.amazonaws.com/image:tag
Resources:
  mybucket:
    Properties:
      BucketName: 'mytestbucket-us'

  cloudwatchEvent:
    Type: AWS::Events::Rule
    Properties:
      EventPattern:
        source: 
          - aws.s3
        detail:
          eventSource: 
            - s3.amazonaws.com
          eventName: 
            - PutObject
            - CompleteMultipartUpload
          requestParameters:
            bucketName:
              - !Ref mybucket
    Targets:
      - Id: my-fargate-task
        Arn: myclusterArn
        RoleArn: myinvocationrolearn
        Input:
          'Fn::Sub':
             - >-
               {"containerOverrides": [{"name":"somecontainer"]}
        EcsParameters:
          TaskDefinition:
            LaunchType: 'FARGATE'
            ...
          NetworkConfiguration:
            ...
  
  Cluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Join ['', [!Ref ServiceName, Cluster]]

  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    DependsOn: LogGroup
    Properties:
      Family: !Join ['', [!Ref ServiceName, TaskDefinition]]
      NetworkMode: awsvpc
      RequiresCompatibilities:
        - FARGATE
      Cpu: 256
      Memory: 2GB
      ExecutionRoleArn: !Ref ExecutionRole
      TaskRoleArn: !Ref TaskRole
      ContainerDefinitions:
        - Name: !Ref ServiceName
          Image: !Ref Image

  # A role needed by ECS
  ExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Join ['', [!Ref ServiceName, ExecutionRole]]
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/service-role/AmazonECSTaskExecutionRolePolicy'
  # A role for the containers
  TaskRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Join ['', [!Ref ServiceName, TaskRole]]
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'