CloudWatch Alarm Creator

Эксперт по мониторингу AWS CloudWatch и настройке алармов.

Основные принципы

• Выбор порогов: Основывайте на исторических данных и бизнес-требованиях
• Статистические методы: Выбирайте подходящую статистику (Average, Sum, Maximum) по характеристикам метрик
• Периоды оценки: Баланс между отзывчивостью и подавлением шума
• Actionable алерты: Каждый аларм должен иметь понятный путь устранения
• Оптимизация стоимости: Эффективные стратегии для минимизации расходов

EC2 Alarm

{
  "AlarmName": "HighCPUUtilization",
  "MetricName": "CPUUtilization",
  "Namespace": "AWS/EC2",
  "Statistic": "Average",
  "Period": 300,
  "EvaluationPeriods": 2,
  "Threshold": 80,
  "ComparisonOperator": "GreaterThanThreshold",
  "Dimensions": [
    {
      "Name": "InstanceId",
      "Value": "i-1234567890abcdef0"
    }
  ],
  "AlarmActions": ["arn:aws:sns:region:account:topic"],
  "TreatMissingData": "notBreaching"
}

ALB Alarm

{
  "AlarmName": "HighTargetResponseTime",
  "MetricName": "TargetResponseTime",
  "Namespace": "AWS/ApplicationELB",
  "Statistic": "Average",
  "Period": 60,
  "EvaluationPeriods": 3,
  "DatapointsToAlarm": 2,
  "Threshold": 1.0,
  "ComparisonOperator": "GreaterThanThreshold",
  "Dimensions": [
    {
      "Name": "LoadBalancer",
      "Value": "app/my-alb/1234567890"
    }
  ],
  "TreatMissingData": "ignore"
}

RDS Alarm

{
  "AlarmName": "HighDatabaseConnections",
  "MetricName": "DatabaseConnections",
  "Namespace": "AWS/RDS",
  "Statistic": "Average",
  "Period": 300,
  "EvaluationPeriods": 2,
  "Threshold": 100,
  "ComparisonOperator": "GreaterThanThreshold",
  "Dimensions": [
    {
      "Name": "DBInstanceIdentifier",
      "Value": "my-database"
    }
  ]
}

Terraform Configuration

resource "aws_cloudwatch_metric_alarm" "ec2_cpu_high" {
  alarm_name          = "ec2-cpu-high-${var.instance_id}"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 2
  metric_name         = "CPUUtilization"
  namespace           = "AWS/EC2"
  period              = 300
  statistic           = "Average"
  threshold           = 80
  alarm_description   = "CPU utilization exceeds 80%"

  dimensions = {
    InstanceId = var.instance_id
  }

  alarm_actions = [aws_sns_topic.alerts.arn]
  ok_actions    = [aws_sns_topic.alerts.arn]

  tags = {
    Environment = var.environment
    ManagedBy   = "terraform"
  }
}

resource "aws_cloudwatch_metric_alarm" "custom_metric" {
  alarm_name          = "custom-error-rate"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 3
  threshold           = 5
  alarm_description   = "Error rate exceeds 5%"

  metric_query {
    id          = "error_rate"
    expression  = "errors/requests*100"
    label       = "Error Rate"
    return_data = true
  }

  metric_query {
    id = "errors"
    metric {
      metric_name = "Errors"
      namespace   = "MyApp"
      period      = 60
      stat        = "Sum"
    }
  }

  metric_query {
    id = "requests"
    metric {
      metric_name = "Requests"
      namespace   = "MyApp"
      period      = 60
      stat        = "Sum"
    }
  }
}

Composite Alarm

{
  "AlarmName": "CompositeSystemHealth",
  "AlarmRule": "ALARM(HighCPU) AND (ALARM(HighMemory) OR ALARM(HighDisk))",
  "AlarmActions": ["arn:aws:sns:region:account:critical-alerts"],
  "AlarmDescription": "System health degraded - multiple metrics breaching"
}

Anomaly Detection

{
  "AlarmName": "AnomalyDetectionCPU",
  "MetricName": "CPUUtilization",
  "Namespace": "AWS/EC2",
  "ThresholdMetricId": "ad1",
  "ComparisonOperator": "GreaterThanUpperThreshold",
  "EvaluationPeriods": 2,
  "Metrics": [
    {
      "Id": "m1",
      "MetricStat": {
        "Metric": {
          "Namespace": "AWS/EC2",
          "MetricName": "CPUUtilization",
          "Dimensions": [{"Name": "InstanceId", "Value": "i-123"}]
        },
        "Period": 300,
        "Stat": "Average"
      }
    },
    {
      "Id": "ad1",
      "Expression": "ANOMALY_DETECTION_BAND(m1, 2)"
    }
  ]
}

SNS Integration

resource "aws_sns_topic" "alerts" {
  name = "cloudwatch-alerts"
}

resource "aws_sns_topic_subscription" "email" {
  topic_arn = aws_sns_topic.alerts.arn
  protocol  = "email"
  endpoint  = "[email protected]"
}

resource "aws_sns_topic_subscription" "lambda" {
  topic_arn = aws_sns_topic.alerts.arn
  protocol  = "lambda"
  endpoint  = aws_lambda_function.alert_handler.arn
}

TreatMissingData Options

Рекомендации по порогам

EC2:
  CPUUtilization:
    warning: 70%
    critical: 85%
    period: 300s

  StatusCheckFailed:
    threshold: 1
    period: 60s

ALB:
  TargetResponseTime:
    p95_warning: 500ms
    p99_critical: 1000ms

  HTTPCode_ELB_5XX:
    threshold: 10
    period: 60s

RDS:
  CPUUtilization:
    warning: 70%
    critical: 85%

  FreeableMemory:
    critical: 256MB

  DiskQueueDepth:
    warning: 5
    critical: 10

Стоимость оптимизации

• Консолидируйте алармы через composite alarms
• Используйте более длинные периоды где возможно
• Удаляйте неиспользуемые алармы регулярно
• Группируйте ресурсы через теги

Тестирование алармов

# Переключить состояние для тестирования уведомлений
aws cloudwatch set-alarm-state \
  --alarm-name "HighCPUUtilization" \
  --state-value ALARM \
  --state-reason "Testing notifications"

Лучшие практики

1. 2 из 3 datapoints — фильтрация временных спайков
2. Percentile-based thresholds — для latency метрик (P95, P99)
3. Multi-level alerts — Warning и Critical уровни
4. Документируйте runbooks — для каждого типа аларма
5. Регулярный аудит — пересматривайте эффективность порогов