---
AWSTemplateFormatVersion: "2010-09-09"
Description: "IAM instance role"

# takes about 3-minute

# https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html
Parameters:
  Id:
    Type: String
    Description: Unique identifier, prefix for all resources created below.

  KmsCmkArn:
    Type: String
    Description: KMS CMK ARN that de/encrypts resources.

  S3BucketName:
    Type: String
    Description: S3 bucket name to store.

  S3BucketDbBackupName:
    Type: String
    Default: ""
    Description: S3 bucket name to download backups from.

Mappings:
  ServicePrincipals:
    aws-cn:
      ec2: ec2.amazonaws.com.cn
    aws:
      ec2: ec2.amazonaws.com

Conditions:
  HasS3BucketDbBackupName:
    Fn::Not:
      - Fn::Equals:
          - Ref: S3BucketDbBackupName
          - ""

Resources:
  # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-iam-role.html
  InstanceRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Join ["-", [!Ref Id, "instance-role"]]
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - Fn::FindInMap:
                    - ServicePrincipals
                    - Ref: AWS::Partition
                    - ec2
            Action:
              - sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/AmazonSSMFullAccess
        - arn:aws:iam::aws:policy/CloudWatchFullAccess
      Path: /
      Policies:
        - PolicyName: aws-manager-instance-role-policy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - ec2:DescribeInstances # to fetch tags
                  - ec2:DescribeTags # to find network/resource information
                  - ec2:DescribeVolumes # to wait for volume attachment
                Resource: "*"
              - Effect: Allow
                Action:
                  - kms:Encrypt # to generate TLS key and encrypt
                  - kms:GenerateDataKey* # to encrypt TLS key
                  - kms:DescribeKey # to describe the CMK
                Resource: { Ref: KmsCmkArn }
              - Effect: Allow
                Action:
                  - s3:List*
                Resource: "*"
              - Effect: Allow
                Action:
                  - s3:GetObject # to download artifacts
                  - s3:PutObject # to upload generated TLS keys
                Resource:
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/install/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/pki/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/discover/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/discover/bootstrapping-anchor-nodes/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/discover/ready-anchor-nodes/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/discover/ready-non-anchor-nodes/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/backups/*",
                      ],
                    ]
                  - !Join [
                      "",
                      [
                        !Sub "arn:${AWS::Partition}:s3:::",
                        !Ref S3BucketName,
                        "/",
                        !Ref Id,
                        "/events/*",
                      ],
                    ]
              - Effect: Allow
                Action:
                  - cloudwatch:PutMetricData
                Resource: "*"
              - Effect: Allow
                Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:PutLogEvents
                  - logs:DescribeLogStreams
                  - logs:PutRetentionPolicy
                Resource:
                  # Ref: http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html#arn-syntax-cloudwatch-logs
                  - !Sub "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:${Id}"
                  - !Sub "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:${Id}:log-stream:*"
        - Fn::If:
            - HasS3BucketDbBackupName
            - PolicyName: aws-manager-instance-role-policy-for-db-backup
              PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - s3:GetObject # to download backups
                    Resource:
                      - !Join [
                          "",
                          [
                            !Sub "arn:${AWS::Partition}:s3:::",
                            !Ref S3BucketDbBackupName,
                            "/*",
                          ],
                        ]
            - !Ref AWS::NoValue

  # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-iam-instanceprofile.html
  InstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties:
      InstanceProfileName: !Join ["-", [!Ref Id, "instance-profile"]]
      Path: "/"
      Roles:
        - !Ref InstanceRole

Outputs:
  InstanceRoleArn:
    Value: !GetAtt InstanceRole.Arn
    Description: Role ARN

  InstanceProfileArn:
    Value: !GetAtt InstanceProfile.Arn
    Description: Instance profile ARN