AWSTemplateFormatVersion: '2010-09-09'
Description: "This CloudFormation template listens for the 'aws.health' event sent by the EventBus Sender for each member account provisioned as 'sender-org-stacks' in AWS Organizations. Additionally, received events are sent to SNS topics and sent to Hangout Chat through Lambda subscribers."

Parameters:
  Project:
    Type: String
    MinLength: '3'
    MaxLength: '8'
    Description: Project name (3-8 characters)
    Default: cops
  Region:
    Type: String
    Description: AWS Region
    AllowedValues:
      - ap-northeast-2
      - us-east-1
      - us-west-2
    Default: ap-northeast-2
  ECRImageUri:
    Type: String
    Description: AWS Health Event Notifier Image
  GchatWebhookUrl:
    Type: String
    Description: Google Chat Webhook URL
  OrgId:
    Type: String
    MinLength: '4'
    MaxLength: '16'
    Description: Organization ID to allow events from.
  Owner:
    Type: String
    Description: Resource owner
  Team:
    Type: String
    Description: Team name
    Default: PEOps

Resources:
  DelibirdLambda:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: !Sub ${Project}-health-delibird-lambda
      PackageType: Image
      Architectures:
        - arm64
      MemorySize: 256
      Timeout: 300
      Code:
        ImageUri: !Ref ECRImageUri
      Role: !GetAtt DelibirdLambdaRole.Arn
      Environment:
        Variables:
          GCHAT_WEBHOOK_URL: !Ref GchatWebhookUrl
      Tags:
        - Key: Name
          Value: !Sub ${Project}-health-delibird-lambda
        - Key: Project
          Value: !Ref Project
        - Key: Owner
          Value: !Ref Owner
        - Key: Team
          Value: !Ref Team

  DelibirdLambdaRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Sub ${Project}HealthDelibirdLambdaRole
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Policies:
        - PolicyName: !Sub ${Project}LambdaExecutionPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: "Allow"
                Action:
                  - "logs:CreateLogGroup"
                  - "logs:CreateLogStream"
                  - "logs:PutLogEvents"
                Resource: "arn:aws:logs:*:*:*"
              - Effect: "Allow"
                Action:
                  - "ecr:*"
                Resource: "*"
              - Effect: "Allow"
                Action:
                  - "kms:Decrypt"
                Resource: "*"
      Tags:
        - Key: Name
          Value: !Sub ${Project}HealthDelibirdLambdaRole
        - Key: Project
          Value: !Ref Project
        - Key: Owner
          Value: !Ref Owner
        - Key: Team
          Value: !Ref Team

  HealthKMS:
    Type: AWS::KMS::Key
    Properties:
      Description: KMS key for SNS encryption
      KeySpec: SYMMETRIC_DEFAULT
      KeyUsage: ENCRYPT_DECRYPT
      KeyPolicy:
        Version: '2012-10-17'
        Id: 'key-default-1'
        Statement:
          - Sid: 'Enable IAM User Permissions'
            Effect: 'Allow'
            Principal:
              AWS: !Sub 'arn:aws:iam::${AWS::AccountId}:root'
            Action: 'kms:*'
            Resource: '*'
          - Sid: 'Allow EventBridge to use the key'
            Effect: 'Allow'
            Principal:
              Service: 'events.amazonaws.com'
            Action:
              - 'kms:Decrypt'
              - 'kms:GenerateDataKey'
            Resource: '*'
      Tags:
        - Key: Name
          Value: !Sub ${Project}-health-kms
        - Key: Project
          Value: !Ref Project
        - Key: Owner
          Value: !Ref Owner
        - Key: Team
          Value: !Ref Team

  HealthKMSAlias:
    Type: AWS::KMS::Alias
    Properties:
      AliasName: !Sub alias/${Project}-health-kms
      TargetKeyId: !Ref HealthKMS

  HealthTopic:
    Type: AWS::SNS::Topic
    Properties:
      TopicName: !Sub ${Project}-aws-health-topic
      KmsMasterKeyId: !Ref HealthKMSAlias
      Tags:
        - Key: Name
          Value: !Sub ${Project}-health-topic
        - Key: Project
          Value: !Ref Project
        - Key: Owner
          Value: !Ref Owner
        - Key: Team
          Value: !Ref Team

  HealthTopicPolicy:
    Type: AWS::SNS::TopicPolicy
    Properties:
      Topics:
        - !Ref HealthTopic
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Sid: "__default_statement_ID"
            Effect: Allow
            Principal:
              AWS: "*"
            Action:
              - SNS:GetTopicAttributes
              - SNS:SetTopicAttributes
              - SNS:AddPermission
              - SNS:RemovePermission
              - SNS:DeleteTopic
              - SNS:Subscribe
              - SNS:ListSubscriptionsByTopic
              - SNS:Publish
            Resource: !Ref HealthTopic
            Condition:
              StringEquals:
                AWS:SourceOwner: !Ref AWS::AccountId
          - Sid: "AllowEventBridgeToPublish"
            Effect: "Allow"
            Principal:
              Service: "events.amazonaws.com"
            Action: "sns:Publish"
            Resource: !Ref HealthTopic

  HealthTopicSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      TopicArn: !Ref HealthTopic
      Protocol: lambda
      Endpoint: !GetAtt DelibirdLambda.Arn

  HealthEventBus:
    Type: AWS::Events::EventBus
    Properties:
      Name: !Sub ${Project}-health-collector-bus
      Description: "Receive all aws.health events and notify to sns topic."
      Tags:
        - Key: Name
          Value: !Sub ${Project}-health-collector-bus
        - Key: Project
          Value: !Ref Project
        - Key: Owner
          Value: !Ref Owner
        - Key: Team
          Value: !Ref Team

  HealthEventBusPolicy:
    Type: AWS::Events::EventBusPolicy
    Properties:
      EventBusName: !Ref HealthEventBus
      StatementId: "AllowPutHealthEvents"
      Statement:
          Effect: "Allow"
          Principal: "*"
          Action: "events:PutEvents"
          Resource: !GetAtt HealthEventBus.Arn

  HealthEventBusOrgPolicy:
    Type: AWS::Events::EventBusPolicy
    Properties:
      EventBusName: !Ref HealthEventBus
      StatementId: "AllowPutHealthEventsForOrganizationId"
      Statement:
          Effect: "Allow"
          Principal: "*"
          Action: "events:PutEvents"
          Resource: !GetAtt HealthEventBus.Arn
          Condition:
            StringEquals:
              "aws:PrincipalOrgID": !Ref OrgId

  HealthProcessorRule:
    Type: AWS::Events::Rule
    Properties:
      Name: !Sub ${Project}-health-processor-rule
      Description: "Notify all aws.health events to sns topic"
      EventBusName: !Ref HealthEventBus
      EventPattern:
        source:
          - aws.health
          - custom.health
      Targets:
        - Arn: !Ref HealthTopic
          Id: HealthTopicTarget
      State: "ENABLED"

  LambdaInvokePermission:
    Type: AWS::Lambda::Permission
    Properties:
      FunctionName: !Ref DelibirdLambda
      Action: lambda:InvokeFunction
      Principal: sns.amazonaws.com
      SourceArn: !Ref HealthTopic

Outputs:
  LambdaArn:
    Description: ARN of the Delibird Lambda Function
    Value: !GetAtt DelibirdLambda.Arn
  SNSTopicArn:
    Description: ARN of the Health SNS Topic
    Value: !Ref HealthTopic
  EventBusArn:
    Description: ARN of the Health Event Bus
    Value: !GetAtt HealthEventBus.Arn
  ECRArn:
    Description: ARN of the ECR
    Value: !Select [0, !Split [":", !Ref ECRImageUri]]