AWSTemplateFormatVersion: '2010-09-09'
Description: ECS service scheduling GC against specified git projects
Parameters:
  ClusterStackName:
    Description: Stack name of the ECS cluster to deploy this service onto
    Type: String
    Default: gerrit-cluster
  ProjectList:
    Description: Comma separated list of projects to perform GC against
    Type: CommaDelimitedList
    Default: ''
  EnvironmentName:
    Description: An environment name used to build the log stream names
    Type: String
    Default: test
  TemplateBucketName:
    Description: S3 bucket containing cloudformation templates
    Type: String
  DockerImageFQN:
    Description: Fully qualified name of the git-gc docker image
    Type: String
  ScheduleCronExpression:
    Description: Cron expression string to schedule GC at
    Type: String
  GitSourcePath:
    Description: The absolute path storing git data
    Type: String

Mappings:
  Gerrit:
    Volume:
      Git: gerrit-git
  GitGC:
    Task:
      Name: git-gc

Resources:
    TaskDefinition:
        Type: AWS::ECS::TaskDefinition
        Properties:
            Family: !FindInMap ['GitGC', 'Task', 'Name']
            TaskRoleArn: !GetAtt ECSTaskExecutionRoleStack.Outputs.TaskExecutionRoleRef
            ExecutionRoleArn: !GetAtt ECSTaskExecutionRoleStack.Outputs.TaskExecutionRoleRef
            NetworkMode: bridge
            PlacementConstraints:
                - Expression: !Sub 'attribute:target_group =~ master.*'
                  Type: "memberOf"
            ContainerDefinitions:
                - Name: !FindInMap ['GitGC', 'Task', 'Name']
                  Essential: true
                  Image: !Ref DockerImageFQN
                  Environment:
                    - Name: GC_PROJECT_LIST
                      Value: !Join [',', !Ref ProjectList]
                  MountPoints:
                    - SourceVolume: !FindInMap ['Gerrit', 'Volume', 'Git']
                      ContainerPath: /git
                  Cpu: 1024
                  Memory: 1024
                  LogConfiguration:
                    LogDriver: awslogs
                    Options:
                        awslogs-group: !Ref ClusterStackName
                        awslogs-region: !Ref AWS::Region
                        awslogs-stream-prefix: !Ref EnvironmentName
            Volumes:
              - Name: !FindInMap ['Gerrit', 'Volume', 'Git']
                Host:
                  SourcePath: !Ref GitSourcePath

    ECSTaskExecutionRoleStack:
      Type: AWS::CloudFormation::Stack
      Properties:
        TemplateURL: !Join [ '', ['https://', !Ref TemplateBucketName, '.s3.amazonaws.com/cf-gerrit-task-execution-role.yml'] ]
        TimeoutInMinutes: '5'

    EventsInvokeTaskRole:
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument:
          Statement:
            - Effect: Allow
              Principal:
                Service: [events.amazonaws.com]
              Action:
                - sts:AssumeRole
        Path: /
        Policies:
          - PolicyName: "AllowTaskInvoke"
            PolicyDocument:
              Statement:
                - Effect: "Allow"
                  Action:
                    - 'ecs:RunTask'
                  Resource: !Sub
                    - "arn:aws:ecs:*:${AWS::AccountId}:task-definition/${TaskName}:*"
                    - { TaskName: !FindInMap ['GitGC', 'Task', 'Name'] }
                  Condition:
                    ArnLike:
                      ecs:cluster: !Sub
                        - "arn:aws:ecs:*:${AWS::AccountId}:cluster/${ClusterName}"
                        - { ClusterName:
                              { Fn::ImportValue: !Join [':', [!Ref 'ClusterStackName', 'ClusterName']] }
                        }
                - Effect: "Allow"
                  Action: "iam:PassRole"
                  Resource: "*"
                  Condition:
                    StringLike:
                      iam:PassedToService: "ecs-tasks.amazonaws.com"

    TaskSchedule:
      Type: AWS::Events::Rule
      Properties:
        Description: "Run git garbage collection on a list of specified projects"
        Name: git-GC
        ScheduleExpression: !Sub "cron(${ScheduleCronExpression})"
        State: ENABLED
        Targets:
          - Id: git-gc-master
            RoleArn: !GetAtt EventsInvokeTaskRole.Arn
            EcsParameters:
              TaskDefinitionArn: !Ref TaskDefinition
              TaskCount: 1
            Arn:
              Fn::ImportValue:
                !Join [':', [!Ref 'ClusterStackName', 'ClusterArn']]