template.yml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  ws-sessions-app

  SAM Template for ws-sessions-app to demonstrate how to keep context for anonymous users
  when they are reconnecting to a WebSocket API. The app shows how to generate a session ID,
  store session context on disconnect, and link different connection IDs from WebSocket
  to a particular user.
  
Globals:
  Function:
    Runtime: python3.9
    MemorySize: 128
    Timeout: 15

Parameters:
  ApiStageName:
    Type: String
    Default: Prod
    Description: REQUIRED The name of Websocket API deployment stage
    MinLength: 3
    MaxLength: 10
    AllowedPattern: ^[A-Za-z]+$
    ConstraintDescription: Capital or small letters only.

Resources:
##### Websocket API #####
  Websocket:
    Type: AWS::ApiGatewayV2::Api
    Properties:
      Name: SessionManagementWebsocketApi
      ProtocolType: WEBSOCKET
      RouteSelectionExpression: "$request.body.action"
  ConnectRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref Websocket
      RouteKey: $connect
      AuthorizationType: NONE
      OperationName: ConnectRoute
      Target: !Join [ '/', ['integrations', !Ref ConnectInteg] ]
  ConnectInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref Websocket
      Description: Connect Integration
      IntegrationType: AWS_PROXY
      IntegrationUri: !Sub arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${OnConnectFunction.Arn}/invocations
  DisconnectRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref Websocket
      RouteKey: $disconnect
      AuthorizationType: NONE
      OperationName: DisconnectRoute
      Target: !Join [ '/', ['integrations', !Ref DisconnectInteg]]
  DisconnectInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref Websocket
      Description: Disconnect Integration
      IntegrationType: AWS_PROXY
      IntegrationUri: !Sub arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${OnDisconnectFunction.Arn}/invocations
  TeleprinterRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref Websocket
      RouteKey: teleprinter
      AuthorizationType: NONE
      OperationName: TeleprinterRoute
      Target: !Join [ '/', ['integrations', !Ref TeleprinterInteg]]
  TeleprinterInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref Websocket
      Description: Teleprinter Integration
      IntegrationType: AWS_PROXY
      IntegrationUri: !Sub arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${TeleprinterFunction.Arn}/invocations
  Deployment:
    Type: AWS::ApiGatewayV2::Deployment
    DependsOn:
    - ConnectRoute
    - DisconnectRoute
    - TeleprinterRoute
    Properties:
      ApiId: !Ref Websocket
  Stage:
    Type: AWS::ApiGatewayV2::Stage
    Properties:
      StageName: !Ref ApiStageName
      Description: Prod Stage
      DeploymentId: !Ref Deployment
      ApiId: !Ref Websocket

##### DynamoDB table for managing Websocket connections #####
  ConnectionsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
      - AttributeName: "userId"
        AttributeType: "S"
      - AttributeName: "connectionId"
        AttributeType: "S"
      - AttributeName: "active"
        AttributeType: "S"
      - AttributeName: "lastSeen"
        AttributeType: "N"
      KeySchema:
      - AttributeName: "userId"
        KeyType: "HASH"
      GlobalSecondaryIndexes:
      - IndexName: connectionId-index
        Projection:
          ProjectionType: ALL
        ProvisionedThroughput:
          WriteCapacityUnits: 5
          ReadCapacityUnits: 5
        KeySchema:
        - KeyType: HASH
          AttributeName: connectionId
      - IndexName: lastSeen-index
        Projection:
          ProjectionType: KEYS_ONLY
        ProvisionedThroughput:
          WriteCapacityUnits: 5
          ReadCapacityUnits: 5
        KeySchema:
        - KeyType: HASH
          AttributeName: active
        - KeyType: RANGE
          AttributeName: lastSeen
      ProvisionedThroughput:
        ReadCapacityUnits: 5
        WriteCapacityUnits: 5
      SSESpecification:
        SSEEnabled: True

  SessionsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
      - AttributeName: "userId"
        AttributeType: "S"
      KeySchema:
      - AttributeName: "userId"
        KeyType: "HASH"
      ProvisionedThroughput:
        ReadCapacityUnits: 5
        WriteCapacityUnits: 5
      SSESpecification:
        SSEEnabled: True

##### EventBridge Scheduler #####
  OnDeleteSchedulerFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: app.handler
      Runtime: python3.9
      CodeUri: handlers/onDelete/
      MemorySize: 128
      Environment:
        Variables:
          CONNECTIONS_TABLE_NAME: !Ref ConnectionsTable
          SESSIONS_TABLE_NAME: !Ref SessionsTable
      Policies:
      - DynamoDBCrudPolicy:
          TableName: !Ref ConnectionsTable
      - DynamoDBCrudPolicy:
          TableName: !Ref SessionsTable
      Events:
        Schedule:
          Type: ScheduleV2
          Properties:
            ScheduleExpression: rate(5 minute)

##### Lambda functions #####
  OnConnectFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: handlers/onConnect/
      Handler: app.handler
      Environment:
        Variables:
          TABLE_NAME: !Ref ConnectionsTable
      Policies:
      - DynamoDBCrudPolicy:
          TableName: !Ref ConnectionsTable
  OnConnectPermission:
    Type: AWS::Lambda::Permission
    DependsOn:
      - Websocket
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !Ref OnConnectFunction
      Principal: apigateway.amazonaws.com
  OnDisconnectFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: handlers/onDisconnect/
      Handler: app.handler
      Environment:
        Variables:
          TABLE_NAME: !Ref ConnectionsTable
      Policies:
      - DynamoDBCrudPolicy:
          TableName: !Ref ConnectionsTable
  OnDisconnectPermission:
    Type: AWS::Lambda::Permission
    DependsOn:
      - Websocket
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !Ref OnDisconnectFunction
      Principal: apigateway.amazonaws.com
  
  TeleprinterFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: handlers/teleprinter
      Handler: app.handler
      Timeout: 600
      Environment:
        Variables:
          API_URL: !Join [ '', [ 'https://', !Ref Websocket, '.execute-api.',!Ref 'AWS::Region','.amazonaws.com/',!Ref 'ApiStageName'] ]
          CONNECTIONS_TABLE_NAME: !Ref ConnectionsTable
          SESSIONS_TABLE_NAME: !Ref SessionsTable
      Policies:
      - DynamoDBCrudPolicy:
          TableName: !Ref ConnectionsTable
      - DynamoDBCrudPolicy:
          TableName: !Ref SessionsTable
      - Statement:
        - Effect: Allow
          Action:
          - 'execute-api:ManageConnections'
          Resource:
          - !Sub 'arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${Websocket}/*'
  TeleprinterPermission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !Ref TeleprinterFunction
      Principal: apigateway.amazonaws.com
      SourceArn: !Sub 'arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${Websocket}/*'
    
Outputs:
  WebSocketURL:
    Description: "The WSS Protocol URL to connect to. Copy and paste to the field on the frontend."
    Value: !Join [ '', [ 'wss://', !Ref Websocket, '.execute-api.',!Ref 'AWS::Region','.amazonaws.com/',!Ref 'ApiStageName'] ]