How to attach authorization/api key to the sam cli generated api?

Question

I used sam cli , to create a project. when I package this and deploy , it creates the lambda and also the api gateway with stage and prod stages, policy, roles e.t.c by default, without having to explicitly define in the cloudformation template ( see code below) . as it generates the api gateway automatically, how do i add/attach say if i wanted to add a api key or some kind of authorization for my api generated by template below?

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  simple-node-api
  Sample SAM Template for simple-node-api

Globals:
  Function:
    Timeout: 3

Resources:
 ServerlessHttpApi:
    Type: AWS::Serverless::Api
    Properties:
      StageName: Prod
      Auth:
        ApiKeyRequired: true # sets for all methods
      DefinitionBody:
        swagger:2.0
        paths:
          "/myresource":
              post:
                 x-amazon-apigateway-integration
                    httpMethod: post
                    type: aws_proxy
                    uri: ...

 ApiKey: 
    Type: AWS::ApiGateway::ApiKey
    Properties: 
      Name: !Join ["", [{"Ref": "AWS::StackName"}, "-apikey"]]
      Description: "CloudFormation API Key V1"
      Enabled: true
      GenerateDistinctId: false
      Value: abcdefg123456
      StageKeys:
        - RestApiId: !Ref ServerlessHttpApi
          StageName: Prod

  ApiUsagePlan:
    Type: "AWS::ApiGateway::UsagePlan"
    Properties:
      ApiStages: 
        - ApiId: !Ref ServerlessHttpApi
          Stage: Prod
      Description: !Join [" ", [{"Ref": "AWS::StackName"}, "usage plan"]]
      Quota:
        Limit: 1000
        Period: MONTH
      UsagePlanName: !Join ["", [{"Ref": "AWS::StackName"}, "-usage-plan"]]

  ApiUsagePlanKey:
    Type: "AWS::ApiGateway::UsagePlanKey"
    DependsOn: 
      - ServerlessHttpApi
    Properties:
      KeyId: !Ref ApiKey
      KeyType: API_KEY
      UsagePlanId: !Ref ApiUsagePlan

  HelloWorldfunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: hello-world/
      Handler: app.lambdaHandler
      Runtime: python3.7
      Events:
        HelloWorld:
          Type: Api
          Properties:
            RestApiId: !Ref ServerlessHttpApi
            Path: /hello
            Method: get

Outputs:
  ServerlessHttpApi:
    Description: API Gateway endpoint URL for Prod stage for Hello World function
    Value:
      Fn::Sub: https://${ServerlessHttpApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"
  HelloWorldfunction:
    Description: Express Backend Lambda Function ARN
    Value: !Sub HelloWorldfunction.Arn
  HelloWorldFunctionIamRole:
    Description: Implicit IAM Role created for Hello World function
    Value: !Sub HelloWorldFunctionRole.Arn

Answer 1

I modified your code to use the API keys as shown here.

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  simple-node-api
  Sample SAM Template for simple-node-api

Globals:
  Function:
    Timeout: 3

Resources:

  ServerlessHttpApi:
    Type: AWS::Serverless::Api
    Properties:
      StageName: Prod
      Auth:
        ApiKeyRequired: true # sets for all methods

  ApiKey: 
    Type: AWS::ApiGateway::ApiKey
    DependsOn: [ApiUsagePlan]
    Properties: 
      Name: !Join ["", [{"Ref": "AWS::StackName"}, "-apikey"]]
      Description: "CloudFormation API Key V1"
      Enabled: true
      GenerateDistinctId: false
      Value: abcdefg123456665ffghsdghfgdhfgdh4565
      StageKeys:
        - RestApiId: !Ref ServerlessHttpApi
          StageName: Prod

  ApiUsagePlan:
    Type: "AWS::ApiGateway::UsagePlan"
    DependsOn:
      - ServerlessHttpApiProdStage
    Properties:
      ApiStages: 
        - ApiId: !Ref ServerlessHttpApi
          Stage: Prod
      Description: !Join [" ", [{"Ref": "AWS::StackName"}, "usage plan"]]
      Quota:
        Limit: 1000
        Period: MONTH
      UsagePlanName: !Join ["", [{"Ref": "AWS::StackName"}, "-usage-plan"]]

  ApiUsagePlanKey:
    Type: "AWS::ApiGateway::UsagePlanKey"
    DependsOn: 
      - ServerlessHttpApi
    Properties:
      KeyId: !Ref ApiKey
      KeyType: API_KEY
      UsagePlanId: !Ref ApiUsagePlan

  HelloWorldfunction:
    Type: AWS::Serverless::Function
    Properties:
      #CodeUri: hello-world/
      CodeUri: ./
      Handler: app.lambdaHandler
      Runtime: python3.7
      Events:
        HelloWorld:
          Type: Api
          Properties:
            RestApiId: !Ref ServerlessHttpApi
            Path: /hello
            Method: get

Outputs:
  ServerlessHttpApi:
    Description: API Gateway endpoint URL for Prod stage for Hello World function
    Value:
      Fn::Sub: https://${ServerlessHttpApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"
  HelloWorldfunction:
    Description: Express Backend Lambda Function ARN
    Value: !Sub HelloWorldfunction.Arn
  HelloWorldFunctionIamRole:
    Description: Implicit IAM Role created for Hello World function
    Value: !Sub HelloWorldFunctionRole.Arn

I commented out some parts so that I can run the code, and I can confirm that it deploys and the API auth is set and API key present: