Built in and Custom Metrics

In this guide, we’ll explore the three primary metric types in AWS CloudWatch—built-in metrics, custom metrics, and usage metrics—and demonstrate how to apply them when monitoring an RDS instance in a VPC. By the end, you’ll understand how to gain a comprehensive view of your resource health, application performance, and usage quotas.

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1. Metric Types Overview

CloudWatch collects and organizes data into different metric categories. Leveraging all three types helps you:

• Track core resource performance
• Gather application-specific insights
• Monitor service consumption against quotas

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1.1 Built-in Metrics

CloudWatch automatically publishes metrics for over 70 AWS services. Examples include:

• CPUUtilization
• NetworkIn / NetworkOut
• DiskReadBytes / DiskWriteBytes

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1.2 Custom Metrics

When default metrics aren’t enough, you can push any numeric data via the PutMetricData API. Common examples:

• Order processing rate
• Cache hit ratio
• Endpoint response time

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1.3 Usage Metrics

Usage metrics track how close you are to AWS service quotas (limits). These are crucial for:

• Monitoring API call volumes
• Ensuring you don’t exceed resource limits
• Forecasting future capacity needs

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2. Practical Example: Monitoring RDS in a VPC

Let’s apply these metric types to an Amazon RDS instance running in a Virtual Private Cloud.

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2.1 Built-in RDS Metrics

AWS RDS publishes dozens of metrics by default. Key ones include:

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2.2 Custom RDS Metrics

Enhance observability with application-specific data:

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3. Next Steps

With metrics in place, you can now:

• Set up CloudWatch Alarms to get notified on thresholds
• Build CloudWatch Dashboards for real-time visualization
• Integrate with AWS CloudWatch Logs for log monitoring

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Links and References

• AWS CloudWatch Metrics and Dimensions
• Amazon RDS Monitoring
• CloudWatch Pricing
• AWS SDK for Go CloudWatch Guide