# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0

AWSTemplateFormatVersion: "2010-09-09"
Description: "Setting up Gitlab CI Runner AutoScalingGroup"
Parameters:
  VpcID:
    Type: "AWS::EC2::VPC::Id"
    Description: "VPC ID on which EC2 runner instance will reside"
  SubnetIds:
    Type: "List<AWS::EC2::Subnet::Id>"
    Description: "Use Private App Subnets"
  ImageId:
    Type: 'AWS::EC2::Image::Id'
    Description: The image ID to use to create the EC2 runner instance.  
  InstanceType:
    Type: "String"
    Default: "t3.medium"
    Description: "Instance type for EC2 runner instance"
  InstanceName:
    Type: "String"
    Default: "gitlab-runner"
    Description: "Name of the runner instance being created"
  VolumeSize:
    Type: "Number"
    Default: 200
    Description: "Volume size"
  VolumeType:
    Type: "String"
    Default: "gp2"
    Description: "Volume Type Attached to instance"
  MaxSize:
    Type: "Number"
    Default: 6
    Description: "The maximum number of instances in the EC2 autoscaling group."
  MinSize:
    Type: "Number"
    Default: 1
    Description: "The minimum number of instances in the EC2 autoscaling group."
  DesiredCapacity:
    Type: "Number"
    Default: 1
    Description: "The size of the Auto Scaling group."
  MaxBatchSize:
    Type: "Number"
    Default: 1
    Description: "The maximum number of instances that AWS CloudFormation updates at once."
  MinInstancesInService:
    Type: "Number"
    Default: 1
    Description: "The minimum number of instances that must be in service within the Auto Scaling group while CloudFormation updates old instances."
  MaxInstanceLifetime:
    Type: Number
    Description: The maximum amount of time, in seconds, that an instance can be in service. If specified, the value must be either 0 or a number equal to or greater than 86,400 seconds (1 day).
    Default: 604800
  GitlabServerURL:
    Type: String
    Description: URL of the Gitlab server
  DockerImagePath:
    Type: String
    Description: Docker path of the GitLab Runner Docker image    
  RunnerRegistrationTokens:
    Type: "String"
    Description: "Comma delimited tokens for the Gitlab projects you want to register to the runner. See runner registration process: https://docs.gitlab.com/runner/register/. "
  RunnerVersion:
    Type: "String"
    Default: "v1"
    Description: "Version of the Runner"
  RunnerEnvironment:
    Type: "String"
    AllowedValues:
      - "dev"
      - "qa"
      - "prod"
    Description: "The environment that the runner is in"
  LambdaS3Bucket:
    Type: String
    Default: ""
    Description: "The s3 bucket to store the lambda functions in"
  TimeStamp:
    Type: "String"
    Description: "A timestamp for this deployment. This is used to identify the correct lambda code on S3 for deployment."
  Concurrent: 
    Type: "Number"
    Description: "Number of concurrent jobs allowed on a Gitlab Runner"
  CheckInterval:
    Type: "Number"
    Description: "The interval length, in seconds, between new jobs check. If set to 0 or lower, the default value will be used."
  CostCenter:
    Type: String
    Description: Cost center code for the application.
  AppId:
    Type: String
    Description: ID of the application.
  ScaleInCoolDownInSeconds:
    Type: Number
    Default: 600
    Description: The delay before we begin scaling down an autoscaling group. Scale Up does not obey this value.
  CountOfNewJobsBeforeScaling:
    Type: Number
    Default: 2
    Description: The number of jobs that we should be able to take before needing to wait on a scaling event.

Mappings: 
  GitlabRunnerRegisterOptionsMap: 
    dev:
      isLOCKED: "false"
      ACCESS: "not_protected"
    qa:
      isLOCKED: "true"
      ACCESS: "ref_protected"
    prod:
      isLOCKED: "true"
      ACCESS: "ref_protected"
    
Resources:
  GitlabRunnerRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - ec2.amazonaws.com
                - lambda.amazonaws.com
            Action: 'sts:AssumeRole'
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/CloudWatchAgentAdminPolicy'
        - 'arn:aws:iam::aws:policy/AmazonSSMManagedInstanceCore'
      RoleName: GitlabRunnerRole
  InstanceProfile:
    Type: 'AWS::IAM::InstanceProfile'
    Properties:
      InstanceProfileName: GitlabRunnerRole
      Path: /
      Roles:
        - !Ref GitlabRunnerRole
  GitlabRunnerPolicy:
    Type: 'AWS::IAM::ManagedPolicy'
    Properties:
      PolicyDocument:
        Version: 2012-10-17
        Statement:
          - Sid: AllowInvokeLambda
            Action: 'lambda:InvokeFunction'
            Resource: !GetAtt LifeCycleHookFunction.Arn
            Effect: Allow
          - Sid: AllowSSMParameterStoreRead
            Action: 'ssm:GetParameter*'
            Resource: !Sub 'arn:aws:ssm:*:*:parameter/${AWS::StackName}/ci-tokens'
            Effect: Allow
          - Sid: AllowSSMDocumentRead
            Action:
              - 'ssm:ListDocuments'
              - 'ssm:ListCommandInvocations'
            Resource: !Sub 'arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:*'
            Effect: Allow
          - Sid: AllowSSMDocumentSend
            Action: 
              - 'ssm:SendCommand'
            Resource: 
              - !Sub 'arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:instance/*'
              - !Sub 'arn:aws:ssm:*:${AWS::AccountId}:document/${Document}'
            Effect: Allow            
          - Sid: AllowCompleteLifycycle
            Action: 'autoscaling:CompleteLifecycleAction'
            Resource: !Sub 'arn:aws:autoscaling:${AWS::Region}:${AWS::AccountId}:autoScalingGroup:*:autoScalingGroupName/${AWS::StackName}-asg'
            Effect: Allow              
      ManagedPolicyName: !Sub ${AWS::StackName}-policy
      Roles:
        - !Ref GitlabRunnerRole

  RunnerTokenParameter:
    Type: "AWS::SSM::Parameter"
    Properties:
      Name: !Sub "/${AWS::StackName}/ci-tokens"
      Type: "String"
      Value: !Ref RunnerRegistrationTokens

  RunnerSecurityGroup:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      GroupDescription: !Join [ "", [ "Security group for ", !Ref "InstanceName" ] ]
      VpcId: !Ref "VpcID"

  RunnerMonitorSecurityGroup:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      GroupDescription: !Join [ "", [ "Security group for Gitlab Runner Monitor for ", !Ref "InstanceName" ] ]
      VpcId: !Ref "VpcID"

  AllowRunnerMonitorToRunner:
    Type: "AWS::EC2::SecurityGroupIngress"
    Properties:
      Description: "Allow Runner Monitor to access the metric port on the runner"
      GroupId: !Ref RunnerSecurityGroup
      FromPort: 9252
      ToPort: 9252
      IpProtocol: "tcp"
      SourceSecurityGroupId: !Ref RunnerMonitorSecurityGroup

  AllowRunnerMonitorToInternet:
    Type: "AWS::EC2::SecurityGroupEgress"
    Properties:
      Description: "Allow Runner Monitor to access the internet for gitlab/metrics"
      GroupId: !Ref RunnerMonitorSecurityGroup
      CidrIp: "0.0.0.0/0"
      IpProtocol: "-1"

  RunnerLaunchTemplate:
    Type: 'AWS::EC2::LaunchTemplate'
    DependsOn: GitlabRunnerRole
    Properties:
      LaunchTemplateName: !Sub ${AWS::StackName}-launch-template
      LaunchTemplateData:
        BlockDeviceMappings:
          - DeviceName: /dev/xvda
            Ebs:
              VolumeSize: !Ref VolumeSize
              VolumeType: !Ref VolumeType
              Encrypted: true
        IamInstanceProfile:
          Arn: !Sub 'arn:aws:iam::${AWS::AccountId}:instance-profile/GitlabRunnerRole'
        ImageId: !Ref ImageId
        InstanceType: !Ref InstanceType
        SecurityGroupIds:
          - !GetAtt RunnerSecurityGroup.GroupId
        UserData:
          Fn::Base64: !Sub |
            #!/bin/bash -xe
            yum update -y aws-cfn-bootstrap
            /opt/aws/bin/cfn-init -v --stack ${AWS::StackId} --resource RunnerLaunchTemplate --region ${AWS::Region}
            /opt/aws/bin/cfn-signal -e $? --stack ${AWS::StackId} --resource RunnerAutoScalingGroup --region ${AWS::Region}
    Metadata:
      'AWS::CloudFormation::Init':
        config:
          files:
            /etc/cfn/cfn-hup.conf:
              owner: 'root'
              group: 'root'
              mode: '000400'
              content: !Sub |
                [main]
                stack=${AWS::StackId}
                region=${AWS::Region}
            /etc/cfn/hooks.d/cfn-auto-reloader.conf:
              content: !Sub |
                [cfn-auto-reloader-hook]
                triggers=post.update
                path=Resources.RunnerLaunchTemplate.Metadata.AWS::CloudFormation::Init
                action=/opt/aws/bin/cfn-init -v --stack ${AWS::StackName} --region ${AWS::Region} --resource RunnerLaunchTemplate
                runas=root
            /etc/gitlab-runner/config.toml:
              content: !Sub |
                concurrent = ${Concurrent}
                check_interval = ${CheckInterval}
                listen_address = ":9252"
                log_format = "json"
            # https://docs.gitlab.com/runner/best_practice/#graceful-shutdown
            /etc/systemd/system/gitlab-runner.service.d/kill.conf:
              content: |
                [Service]
                KillSignal=SIGQUIT
                TimeoutStopSec=3600
          commands:
            01InstallDocker:
              command: sudo yum -y install docker
            02StartDocker:
              command: sudo service docker start
            03DownloadGitlabRunner:
              command: sudo wget -O /usr/bin/gitlab-runner https://gitlab-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-runner-linux-amd64
            04ChmodGitlabRunner:
              command: sudo chmod a+x /usr/bin/gitlab-runner
            05AddUser:
              command: sudo useradd --comment 'GitLab Runner' --create-home gitlab-runner --shell /bin/bash
            06InstallGitlabRunner:
              command: sudo gitlab-runner install --user=gitlab-runner --working-directory=/home/gitlab-runner
            07StartGitlabRunner:
              command: sudo gitlab-runner start              
            08SetRegion:
              command: !Sub 'aws configure set default.region ${AWS::Region}'
            09ConfigureDockerExecutor:
              command: !Sub 
                - |
                  for GitlabGroupToken in `aws ssm get-parameters --names /${AWS::StackName}/ci-tokens --query 'Parameters[0].Value' | sed -e "s/\"//g" | sed "s/,/ /g"`;do
                      sudo gitlab-runner register \
                      --non-interactive \
                      --url "${GitlabServerURL}" \
                      --registration-token $GitlabGroupToken \
                      --executor "docker" \
                      --docker-image "${DockerImagePath}" \
                      --description "Gitlab Runner with Docker Executor" \
                      --locked="${isLOCKED}" --access-level "${ACCESS}" \
                      --docker-volumes "/var/run/docker.sock:/var/run/docker.sock" \
                      --tag-list "${RunnerEnvironment}-${RunnerVersion}-docker"
                  done
                - isLOCKED: !FindInMap [GitlabRunnerRegisterOptionsMap, !Ref RunnerEnvironment, isLOCKED]
                  ACCESS: !FindInMap [GitlabRunnerRegisterOptionsMap, !Ref RunnerEnvironment, ACCESS]
            10StartCfnHup:
              command: systemctl start cfn-hup && systemctl enable cfn-hup
  RunnerAutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    CreationPolicy:
      ResourceSignal:
        Count: !Ref DesiredCapacity
        Timeout: PT5M
    UpdatePolicy:
      AutoScalingRollingUpdate:
        MinInstancesInService: !Ref MinInstancesInService
        MaxBatchSize: !Ref MaxBatchSize
        PauseTime: "PT5M"
        WaitOnResourceSignals: true
        SuspendProcesses:
          - HealthCheck
          - ReplaceUnhealthy
          - AZRebalance
          - AlarmNotification
          - ScheduledActions
    Properties:
      AutoScalingGroupName: !Sub ${AWS::StackName}-asg
      MaxInstanceLifetime: !Ref MaxInstanceLifetime
      LaunchTemplate:
        LaunchTemplateId: !Ref RunnerLaunchTemplate
        Version: !GetAtt 
          - RunnerLaunchTemplate
          - LatestVersionNumber
      DesiredCapacity: !Ref DesiredCapacity
      MinSize: !Ref MinSize
      MaxSize: !Ref MaxSize
      Cooldown: !Ref ScaleInCoolDownInSeconds
      MetricsCollection:
        - Granularity: "1Minute"
          Metrics:
          - "GroupMinSize"
          - "GroupMaxSize"
      Tags:
        - Key: "APP_ID"
          Value: !Ref AppId
          PropagateAtLaunch : true
        - Key: "Name"
          Value: !Ref "InstanceName"
          PropagateAtLaunch : true
        - Key: "COST_CENTER"
          Value: !Ref CostCenter
          PropagateAtLaunch : true
      TerminationPolicies:
        # If the launch configuration is out of date, then replace it.
        # Otherwise we kill the oldest instance and let the runnerManager bring up new instances with latest config ie tokens
        - OldestLaunchConfiguration
        - OldestInstance
      VPCZoneIdentifier: !Ref "SubnetIds"
      ServiceLinkedRoleARN: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/autoscaling.amazonaws.com/AWSServiceRoleForAutoScaling"

  RunnerAutoScalingGroupParameter:
    Type: "AWS::SSM::Parameter"
    Properties:
      Name: !Sub "/${AWS::StackName}/runner-autoscaling-group"
      Type: "String"
      Value: !Ref RunnerAutoScalingGroup

  LifecycleHook:
    Type: AWS::AutoScaling::LifecycleHook
    Properties:
      AutoScalingGroupName: !Ref RunnerAutoScalingGroup
      LifecycleTransition: autoscaling:EC2_INSTANCE_TERMINATING

  DocumentLogGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      RetentionInDays: 14

  Document:
    Type: AWS::SSM::Document
    Properties:
      DocumentType: Command
      Content: !Sub |
        {
          "schemaVersion": "2.2",
          "description": "Gitlab runner graceful shutdown",
          "parameters": {},
          "mainSteps": [
            {
              "action": "aws:runShellScript",
              "name": "TerminateGitlabRunner",
              "inputs":
                {
                  "runCommand": [
                    "ASGNAME='${RunnerAutoScalingGroup}'",
                    "echo $ASGNAME",
                    "LIFECYCLEHOOKNAME='${LifecycleHook}'",
                    "echo $LIFECYCLEHOOKNAME",
                    "INSTANCEID=$(curl http://169.254.169.254/latest/meta-data/instance-id)",
                    "echo $INSTANCEID",
                    "REGION=$(curl http://169.254.169.254/latest/meta-data/placement/availability-zone)",
                    "REGION=${!REGION::-1}",
                    "echo $REGION",
                    "HOOKRESULT='CONTINUE'",
                    "MESSAGE='Gitlab runner process is running'",
                    "echo 'unregistering this runner'",
                    "sudo gitlab-runner unregister --all-runners",
                    "echo 'Waiting for gitlab-runner to stop gracefully'",
                    "sudo gitlab-runner stop",
                    "echo 'completing lifecycle action'",
                    "aws autoscaling complete-lifecycle-action --lifecycle-hook-name ${!LIFECYCLEHOOKNAME} --auto-scaling-group-name ${!ASGNAME} --lifecycle-action-result ${!HOOKRESULT} --instance-id ${!INSTANCEID}  --region ${!REGION}",
                    "echo 'done'"
                  ]
                }
              }
            ]
          }
      Tags:
        - Key: "APP_ID"
          Value: !Ref AppId
        - Key: "COST_CENTER"
          Value: !Ref CostCenter

  LifeCycleHookFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: !Sub ${AWS::StackName}-asg-lifecycle-hook
      Description: "Gitlab runner autoscaling group lifecycle hook on instance termination."
      Code:
        S3Bucket: !Ref LambdaS3Bucket
        S3Key: !Sub "${AWS::StackName}/${AWS::StackName}-lifecycle-hook-${TimeStamp}.zip"
      Handler: gitlab-runner-lifecycle-hook.lambda_handler
      # TODO: This role is likely too permissive
      Role: !GetAtt GitlabRunnerRole.Arn
      Runtime: python3.9
      Environment:
        Variables:
          DOCUMENT_NAME: !Ref Document
          DOCUMENT_LOG_GROUP_NAME: !Ref DocumentLogGroup
      Tags:
        - Key: "APP_ID"
          Value: !Ref AppId
        - Key: "COST_CENTER"
          Value: !Ref CostCenter

  Permission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: "lambda:InvokeFunction"
      FunctionName: !GetAtt LifeCycleHookFunction.Arn
      Principal: events.amazonaws.com

  Rule:
    Type: AWS::Events::Rule
    Properties:
      EventPattern: !Sub 
        - |
          {
            "source": ["aws.autoscaling"],
            "detail-type": ["EC2 Instance-terminate Lifecycle Action"],
            "detail": {
              "AutoScalingGroupName": ["${ASG}"]
            }
          }
        - { ASG: !Ref RunnerAutoScalingGroup }
      Targets:
      - Arn: !GetAtt LifeCycleHookFunction.Arn
        Id: target

  RunnerMonitorRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
            Action: 'sts:AssumeRole'
      Policies:
        - PolicyName: RunnerMonitorPermissions
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Effect: Allow
                Action:
                  - "autoscaling:DescribeAutoScalingGroups"
                  - "autoscaling:SetDesiredCapacity"
                  - "cloudwatch:PutMetricData"
                  - "ec2:DescribeInstances"
                Resource:
                  - "*"
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole'

  RunnerMonitorLambda:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: !Sub ${AWS::StackName}-runner-monitor
      Description: "Monitors the state of the gitlab runners to trigger autoscaling events"
      Code:
        S3Bucket: !Ref LambdaS3Bucket
        S3Key: !Sub "${AWS::StackName}/${AWS::StackName}-runner-monitor-${TimeStamp}.zip"
      Handler: index.handler
      Role: !GetAtt RunnerMonitorRole.Arn
      Runtime: nodejs14.x
      Timeout: 900
      MemorySize: 256
      ReservedConcurrentExecutions: 1
      VpcConfig:
        SecurityGroupIds:
          - !GetAtt RunnerMonitorSecurityGroup.GroupId
        SubnetIds: !Ref SubnetIds
      Environment:
        Variables:
          AUTOSCALING_GROUP_NAME: !Ref RunnerAutoScalingGroup
          MAXIMUM_CONCURRENT_JOBS_PER_RUNNER: !Ref Concurrent
          COUNT_OF_NEW_JOBS_BEFORE_SCALING: !Ref CountOfNewJobsBeforeScaling
          RUNNER_METRIC_NAMESPACE: !Sub "${AWS::StackName}-runner-metrics"
          RUNNER_JOB_COUNT_METRIC_NAME: !Sub "${AWS::StackName}-job-count"
          RUNNER_TARGET_CAPACITY_METRIC_NAME: !Sub "${AWS::StackName}-target-capacity"
          RUNNER_ACTUAL_CAPACITY_METRIC_NAME: !Sub "${AWS::StackName}-actual-capacity"
      Tags:
        - Key: "APP_ID"
          Value: !Ref AppId
        - Key: "COST_CENTER"
          Value: !Ref CostCenter

  RunnerMonitorLambdaPermission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: "lambda:InvokeFunction"
      FunctionName: !GetAtt RunnerMonitorLambda.Arn
      Principal: events.amazonaws.com
      SourceArn: !GetAtt ExecuteRunnerMonitor.Arn

  ExecuteRunnerMonitor:
    Type: AWS::Events::Rule
    Properties:
      Description: Monitor Gitlab-Runners every minute
      ScheduleExpression: rate(1 minute)
      Targets:
        - Arn: !GetAtt RunnerMonitorLambda.Arn
          Id: TargetFunction1

Outputs:
  RunnerInstanceID:
    Description: "AutoScalingGroup Name of the GITLAB CI Runner is: "
    Value: !Ref "RunnerAutoScalingGroup"