https://twitter.com/brianleroux/status/1577979058700578816

Disconnect.yml

  DisconnectWSLambda:
    Type: AWS::Serverless::Function
    Properties:
      Handler: index.handler
      CodeUri: "/var/task/src/ws/disconnect"
      Runtime: nodejs16.x
      Architectures:
      - x86_64
      MemorySize: 1152
  DisconnectWSRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId:
        Ref: WS
      RouteKey: "$disconnect"
      OperationName: DisconnectWSRoute
      Target:
        Fn::Join:
        - "/"
        - - integrations
          - Ref: DisconnectWSIntegration
  DisconnectWSIntegration:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId:
        Ref: WS
      IntegrationType: AWS_PROXY
      IntegrationUri:
        Fn::Sub:
        - arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${DisconnectWSLambda.Arn}/invocations
        - {}
  DisconnectWSPermission:
    Type: AWS::Lambda::Permission
    DependsOn:
    - WS
    - DisconnectWSLambda
    Properties:
      Action: lambda:InvokeFunction
      FunctionName:
        Ref: DisconnectWSLambda
      Principal: apigateway.amazonaws.com