AWSTemplateFormatVersion: '2010-09-09'
Description: KMS Key for a GenericSuite aplication.

Parameters:
  AppName:
    Description: Application name
    Type: String
  AppStage:
    Description: Application stage
    Type: String
  KmsKeyAlias:
    Description: KMS Key alias
    Type: String
    Default: genericsuite-key

Resources:
  KeyAdminRole:
    Type: "AWS::IAM::Role"
    Properties:
      RoleName: "KeyAdminRole"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "ec2.amazonaws.com"
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: "KeyAdminPolicy"
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: "Allow"
                Action:
                  - "kms:Create*"
                  - "kms:Describe*"
                  - "kms:Enable*"
                  - "kms:List*"
                  - "kms:Put*"
                  - "kms:Update*"
                  - "kms:Revoke*"
                  - "kms:Disable*"
                  - "kms:Get*"
                  - "kms:Delete*"
                  - "kms:ScheduleKeyDeletion"
                  - "kms:CancelKeyDeletion"
                  - "kms:GenerateDataKey"
                Resource: "*"
      Tags:
        - Key: App
          Value: !Ref AppName
        - Key: Stage
          Value: !Ref AppStage

  UseKeyRole:
    Type: "AWS::IAM::Role"
    Properties:
      RoleName: "UseKeyRole"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "ec2.amazonaws.com"
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: "UseKeyPolicy"
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: "Allow"
                Action:
                  - "kms:Encrypt"
                  - "kms:Decrypt"
                  - "kms:ReEncrypt*"
                  - "kms:GenerateDataKey*"
                  - "kms:DescribeKey"
                Resource: "*"
      Tags:
        - Key: App
          Value: !Ref AppName
        - Key: Stage
          Value: !Ref AppStage

  AttachKeyRole:
    Type: "AWS::IAM::Role"
    Properties:
      RoleName: "AttachKeyRole"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "ec2.amazonaws.com"
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: "AttachKeyPolicy"
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: "Allow"
                Action:
                  - "kms:CreateGrant"
                  - "kms:ListGrants"
                  - "kms:RevokeGrant"
                Resource: "*"
      Tags:
        - Key: App
          Value: !Ref AppName
        - Key: Stage
          Value: !Ref AppStage

  # Role for autoscaling groups
  ASGRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Sub ${KmsKeyAlias}-asg-role
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: autoscaling.amazonaws.com
            Action: sts:AssumeRole

  GsKmsKey:
    Type: "AWS::KMS::Key"
    Properties:
      Description: "KMS key for encrypting Secrets Manager secrets and other resources"
      KeyPolicy:
        Version: "2012-10-17"
        Statement:
          - Sid: "Enable IAM User Permissions"
            Effect: "Allow"
            Principal:
              AWS: !Sub "arn:aws:iam::${AWS::AccountId}:root"
            Action: "kms:*"
            Resource: "*"
          - Sid: "Allow access for Key Administrators"
            Effect: "Allow"
            Principal:
              AWS: !GetAtt KeyAdminRole.Arn
            Action: 
              - "kms:Create*"
              - "kms:Describe*"
              - "kms:Enable*"
              - "kms:List*"
              - "kms:Put*"
              - "kms:Update*"
              - "kms:Revoke*"
              - "kms:Disable*"
              - "kms:Get*"
              - "kms:Delete*"
              - "kms:ScheduleKeyDeletion"
              - "kms:CancelKeyDeletion"
              - "kms:GenerateDataKey"
            Resource: "*"
          - Sid: "Allow use of the key"
            Effect: "Allow"
            Principal:
              AWS: !GetAtt UseKeyRole.Arn
            Action: 
              - "kms:Encrypt"
              - "kms:Decrypt"
              - "kms:ReEncrypt*"
              - "kms:GenerateDataKey*"
              - "kms:DescribeKey"
            Resource: "*"
          - Sid: "Allow attachment of persistent resources"
            Effect: "Allow"
            Principal:
              AWS: !GetAtt AttachKeyRole.Arn
            Action: 
              - "kms:CreateGrant"
              - "kms:ListGrants"
              - "kms:RevokeGrant"
            Resource: "*"

          - Sid: "Allow use of the key for EBS volumes"
            Effect: Allow
            Principal:
              Service: ec2.amazonaws.com
            Action:
              - "kms:Encrypt"
              - "kms:Decrypt"
              - "kms:ReEncrypt*"
              - "kms:GenerateDataKey*"
              - "kms:DescribeKey"
            Resource: "*"
          - Sid: "Allow attachment of persistent resources"
            Effect: Allow
            Principal:
              Service: ec2.amazonaws.com
            Action:
              - "kms:CreateGrant"
              - "kms:ListGrants"
              - "kms:RevokeGrant"
            Resource: "*"
            Condition:
              Bool:
                kms:GrantIsForAWSResource: true

          - Sid: "Allow use of the key for ASG"
            Effect: Allow
            Principal:
              AWS: !GetAtt ASGRole.Arn
              # AWS: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/autoscaling.amazonaws.com/${KmsKeyAlias}-asg-role"
            Action:
              - "kms:Encrypt"
              - "kms:Decrypt"
              - "kms:ReEncrypt*"
              - "kms:GenerateDataKey*"
              - "kms:DescribeKey"
            Resource: "*"
          - Sid: "Allow attachment of persistent resources for ASG"
            Effect: Allow
            Principal:
              AWS: !GetAtt ASGRole.Arn
              # AWS: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/autoscaling.amazonaws.com/${KmsKeyAlias}-asg-role"
            Action:
              - "kms:CreateGrant"
              - "kms:ListGrants"
              - "kms:RevokeGrant"
            Resource: "*"
            Condition:
              Bool:
                kms:GrantIsForAWSResource: true

      Tags:
        - Key: App
          Value: !Ref AppName
        - Key: Stage
          Value: !Ref AppStage

  GsKmsKeyAlias:
    Type: "AWS::KMS::Alias"
    Properties:
      # AliasName: "alias/GsKmsKeyAlias_placeholder"
      AliasName: !Sub "alias/${KmsKeyAlias}"
      TargetKeyId: !Ref GsKmsKey

Outputs:
  KeyId:
    Description: KMS Key for Secrets Manager encryption
    Value: !GetAtt GsKmsKey.Arn
    Export:
      Name: !Sub "${KmsKeyAlias}:kms-key-id"
  ASGRoleArn:
    Description: ARN for ASG role
    Value: !GetAtt ASGRole.Arn
    Export:
      Name: !Sub "${KmsKeyAlias}:asg-role-arn"