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Anmazon CloudWatch

Amazon CloudWatch is a monitoring and observability service designed to provide insights into your AWS resources, applications, and services. It collects and tracks metrics, logs, and events, helping you monitor resource usage, set alarms, visualize data, and take automated actions based on pre-defined conditions. Here’s what you need to know about Amazon CloudWatch:

1. Core Components​

  • Metrics: CloudWatch collects metrics from various AWS services (e.g., EC2, RDS, Lambda) and custom applications. Metrics are time-ordered data points that can represent system performance, such as CPU utilization, disk read/writes, and network activity.
  • Logs: You can use CloudWatch Logs to collect, monitor, and analyze log data from applications, services, and systems in real time. Logs can be ingested from AWS services like Lambda, EC2 instances, or custom applications.
  • Events: CloudWatch Events (now part of Amazon EventBridge) allows you to respond to state changes in your AWS resources (e.g., an EC2 instance changing states or an RDS instance backup completing) by automatically triggering actions like invoking a Lambda function or sending an SNS notification.
  • Alarms: CloudWatch Alarms monitor metrics and send notifications or trigger automated responses when pre-defined thresholds are breached.

2. Metrics​

  • Default Metrics: Many AWS services, such as EC2, RDS, S3, and ELB, automatically send basic metrics to CloudWatch (e.g., CPU utilization for EC2 instances).
  • Custom Metrics: You can publish your own custom metrics from applications or on-premises systems using the AWS CLI, CloudWatch Agent, or AWS SDKs. Examples include memory usage, disk I/O, and application-specific metrics like user logins or transaction counts.
  • Granularity: The default metric granularity is 5 minutes for most services. For more detailed monitoring, you can enable detailed monitoring (e.g., for EC2) to collect metrics at 1-minute intervals.
  • Retention: Metrics are stored in CloudWatch for 15 months, allowing you to perform historical analysis with data retention tiers: 1-minute data for 15 days, 5-minute data for 63 days, and 1-hour data for 15 months.

3. Dashboards​

  • CloudWatch Dashboards provide a customizable, centralized view of your metrics and logs. You can create visualizations using charts and graphs to monitor the health and performance of your applications.
  • Cross-Account Visibility: You can create cross-account dashboards to visualize metrics and logs from multiple AWS accounts, simplifying centralized monitoring for large environments.

4. Alarms and Notifications​

  • Alarms: You can set up CloudWatch Alarms to monitor metrics against a threshold (e.g., CPU utilization > 80%) and configure actions when the alarm state changes (e.g., trigger an SNS notification, scale EC2 instances, or invoke a Lambda function).
  • Composite Alarms: Use composite alarms to combine multiple alarms, allowing you to trigger actions based on the states of multiple underlying alarms (e.g., both memory usage and CPU utilization exceeding thresholds).
  • Alarm States: Alarms can have three states: OK, ALARM, and INSUFFICIENT_DATA (e.g., when there’s not enough data to determine the alarm state).

5. Logs Management​

  • CloudWatch Logs: Collect and monitor log files from EC2 instances, applications, and other services. You can configure log groups and log streams to organize logs, and use log retention policies to manage the lifecycle of log data.
  • Log Insights: Use CloudWatch Logs Insights to run queries on your log data, enabling you to filter, aggregate, and visualize log entries. This is helpful for troubleshooting, analyzing application behavior, and gaining insights from log data.
  • Real-Time Monitoring: You can use metric filters to extract key values from log events and convert them into CloudWatch metrics for real-time monitoring.

6. CloudWatch Agent​

  • CloudWatch Agent can be installed on EC2 instances, on-premises servers, and virtual machines to collect both system-level (e.g., memory, disk, swap) and application-level metrics and logs.
  • Custom Metrics: With the CloudWatch Agent, you can collect custom metrics, including memory utilization, disk usage, and other system-level statistics not available by default.

7. Events and Automated Actions​

  • CloudWatch Events / EventBridge: Allows you to monitor state changes in AWS resources and trigger actions automatically. For example, you can use events to respond to EC2 instance changes, S3 bucket modifications, or auto-scaling events.
  • Automated Responses: Use CloudWatch Events to trigger automated workflows, such as invoking a Lambda function, starting an EC2 instance, or sending an SNS notification in response to specific events.

8. CloudWatch Synthetics and Application Insights​

  • CloudWatch Synthetics: Enables you to monitor application endpoints and APIs by running canaries (scripts) that simulate user behavior. This helps detect application issues proactively and measure the performance of web endpoints, APIs, and user flows.
  • Application Insights: Designed to monitor and troubleshoot application performance and availability, Application Insights automatically detects common application problems (e.g., memory leaks, high CPU usage) and provides actionable insights.

9. ServiceLens​

  • AWS ServiceLens provides an integrated view of the health of applications by combining CloudWatch metrics, logs, and AWS X-Ray traces. This offers a complete picture of application performance, tracing requests across services, and identifying bottlenecks or errors.

10. Anomaly Detection​

  • Anomaly Detection: CloudWatch uses machine learning models to identify anomalies in your metrics. When you enable anomaly detection on a metric, it dynamically adjusts thresholds based on historical data patterns, allowing for more accurate alerting and monitoring of unusual behavior.

11. Cross-Account and Cross-Region Observability​

  • CloudWatch enables cross-account observability, allowing you to monitor resources from multiple accounts within an AWS Organization using CloudWatch cross-account dashboards and alarms.
  • Cross-Region: You can aggregate and view metrics and logs across multiple AWS regions, providing centralized monitoring for distributed environments.

12. Integration with Other AWS Services​

  • Auto Scaling: Use CloudWatch Alarms to trigger Auto Scaling policies for EC2 instances, automatically adjusting capacity based on demand.
  • AWS Lambda: Monitor Lambda functions with CloudWatch to gain insights into function execution times, error rates, and other performance metrics.
  • SNS Notifications: Integrate with Amazon SNS to send notifications (e.g., email, SMS) based on CloudWatch Alarms, facilitating real-time alerts and incident management.
  • AWS Systems Manager: Use Systems Manager to configure and manage the CloudWatch Agent on EC2 instances and on-premises servers.

13. Retention and Storage​

  • Metrics Retention: Metrics are stored with different retention periods: 1-minute data for 15 days, 5-minute data for 63 days, and 1-hour data for 15 months.
  • Log Retention: Logs in CloudWatch Logs can be retained for as long as needed. You can set custom retention policies (e.g., 1 day to indefinitely) to manage log storage costs and compliance requirements.

14. Cost Management​

  • Pricing: CloudWatch pricing is based on metrics collected, custom metrics published, logs ingested, log storage, alarms, dashboards, and events processed. To optimize costs:
    • Use metric filters to limit the collection of unnecessary custom metrics.
    • Set appropriate log retention policies to delete old log data and reduce storage costs.
    • Avoid creating overly granular metrics or alarms that could generate high costs.

15. Best Practices​

  • Set Up Alarms for Critical Metrics: Identify key metrics for your applications (e.g., CPU utilization, memory usage, request latency) and set up CloudWatch Alarms to notify you of potential issues.
  • Use Dashboards for Centralized Monitoring: Create CloudWatch Dashboards for a centralized view of metrics and logs, and customize them for different audiences (e.g., ops teams, development teams).
  • Enable Detailed Monitoring: Enable detailed monitoring for resources like EC2 instances to collect 1-minute interval data, which can provide more insights for performance tuning and troubleshooting.
  • Implement Anomaly Detection: Enable Anomaly Detection on key metrics to automatically identify unusual behavior and avoid alert fatigue from static thresholds.