CloudWatch

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: honest-api-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: honest-api
  minReplicas: 3
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70

// # EC2 비정상 종료 → Event → Lambda → Slack 알림
// EventBridge Rule: EC2 상태 변화 감지
// Lambda: Slack Webhook 호출
Lambda: Slack Webhook 호출
resource "aws_lambda_function" "slack_notify" {
  function_name = "ec2-termination-notify"
  role          = aws_iam_role.lambda_role.arn
  runtime       = "python3.9"
  handler       = "index.handler"

  filename = "lambda.zip"   # Slack Webhook 호출 파이썬 코드 압축파일
}

resource "aws_lambda_permission" "allow_event" {
  statement_id  = "AllowExecutionFromEventBridge"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.slack_notify.function_name
  principal     = "events.amazonaws.com"
  source_arn    = aws_cloudwatch_event_rule.ec2_termination.arn
}

resource "aws_cloudwatch_event_rule" "ec2_termination" {
  name        = "ec2-termination-rule"
  description = "Detect EC2 instance termination"

  event_pattern = <<EOF
{
  "source": ["aws.ec2"],
  "detail-type": ["EC2 Instance State-change Notification"],
  "detail": {
    "state": ["termianted", "stopping", "stopped"]
  }
}
EOF
}

resource "aws_cloudwatch_event_target" "send_to_lambda" {
  rule      = aws_cloudwatch_event_rule.ec2_termination.name
  target_id = "LambdaTarget"
  arn       = aws_lambda_function.slack_notify.arn
}

// # DynamoDB Throttling → Event → AutoScaling 정책 증가
// CloudWatch Alarm → EventBridge → Application Autoscaling 정책 증가
resource "aws_cloudwatch_metric_alarm" "dynamodb_throttling" {
  alarm_name          = "dynamodb-throttling-alarm"
  metric_name         = "ReadThrottleEvents"
  namespace           = "AWS/DynamoDB"
  statistic           = "Sum"
  period              = 60
  evaluation_periods  = 1
  threshold           = 1
  comparison_operator = "GreaterThanThreshold"

  dimensions = {
    TableName = "my-table"
  }

  alarm_actions = [aws_cloudwatch_event_rule.throttle_event.arn]
}

// EOF를 넣은 이유는 json같은 값을 멀티라인으로 넣기 위해서 해당 표현식을 사용함.
resource "aws_cloudwatch_event_rule" "throttle_event" {
  name        = "dynamodb-throttle-detected"
  description = "Detect DynamoDB throttling"
  event_pattern = <<EOF
{
  "source": ["aws.cloudwatch"],
  "detail-type": ["CloudWatch Alarm State Change"]
}
EOF
}

resource "aws_cloudwatch_event_target" "increase_scaling" {
  rule      = aws_cloudwatch_event_rule.throttle_event.name
  target_id = "ScalingAction"
  arn       = aws_appautoscaling_policy.dynamodb_scale_up.arn
}

resource "aws_appautoscaling_policy" "dynamodb_scale_up" {
  name               = "scale-up-dynamodb"
  policy_type        = "StepScaling"
  resource_id        = "table/my-table"
  scalable_dimension = "dynamodb:table:ReadCapacityUnits"
  service_namespace  = "dynamodb"

  step_scaling_policy_configuration {
    adjustment_type = "ChangeInCapacity"
    step_adjustment {
      scaling_adjustment = 10
      metric_interval_lower_bound = 0
    }
  }
}

// 매일 09:00 → EventBridge Scheduler → Lambda 실행
resource "aws_cloudwatch_event_rule" "daily_schedule" {
  name        = "daily-09"
  description = "Run every day at 09:00"
  schedule_expression = "cron(0 0 9 * * ? *)"
}

resource "aws_lambda_function" "daily_job" {
  function_name = "daily-job-run"
  role          = aws_iam_role.lambda_role.arn
  runtime       = "python3.9"
  handler       = "index.handler"
  filename      = "daily_job.zip"
}

resource "aws_lambda_permission" "daily_permission" {
  statement_id  = "AllowExecutionFromEventBridge"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.daily_job.function_name
  principal     = "events.amazonaws.com"
  source_arn    = aws_cloudwatch_event_rule.daily_schedule.arn
}

resource "aws_cloudwatch_event_target" "daily_target" {
  rule      = aws_cloudwatch_event_rule.daily_schedule.name
  target_id = "DailyLambda"
  arn       = aws_lambda_function.daily_job.arn
}