> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Built in and Custom Metrics > This guide explores AWS CloudWatchs built-in, custom, and usage metrics for monitoring RDS instances in a VPC. 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. ## 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 | Metric Type | Source | Use Case | | ----------- | --------------------------------------- | ------------------------------------------------------- | | Built-in | AWS-managed (70+ services) | CPU, disk I/O, network throughput, memory usage | | Custom | User-defined via API or SDK | Transaction counts, cache hit rates, API response times | | Usage | AWS service quotas and usage statistics | Track service limits, forecast capacity, avoid overruns | ![The image is a flowchart illustrating the types of metrics: "Published by AWS," "Custom Metrics," and "Usage Metrics," under the main category "Metrics."](https://kodekloud.com/kk-media/image/upload/v1752862371/notes-assets/images/AWS-CloudWatch-Built-in-and-Custom-Metrics/aws-custom-usage-metrics-flowchart.jpg) ### 1.1 Built-in Metrics CloudWatch automatically publishes metrics for over 70 AWS services. Examples include: * CPUUtilization * NetworkIn / NetworkOut * DiskReadBytes / DiskWriteBytes Built-in metrics have a default 1-minute resolution. To enable 1-second (high-resolution) metrics for supported services, see the [CloudWatch detailed monitoring documentation](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/WhatIsCloudWatch.html). ### 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 Custom metrics incur additional charges. Review the [CloudWatch pricing page](https://aws.amazon.com/cloudwatch/pricing/) before publishing high-cardinality or high-frequency data. ### 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 ## 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. ![The image illustrates a diagram of AWS cloud infrastructure, focusing on a Virtual Private Cloud (VPC) with AWS RDS, and highlights built-in and custom metrics for monitoring, such as CPU utilization and average query execution time.](https://kodekloud.com/kk-media/image/upload/v1752862373/notes-assets/images/AWS-CloudWatch-Built-in-and-Custom-Metrics/aws-cloud-infrastructure-vpc-diagram.jpg) ### 2.1 Built-in RDS Metrics AWS RDS publishes dozens of metrics by default. Key ones include: | Metric Name | Description | Unit | | -------------------- | ---------------------------------- | ----------- | | CPUUtilization | Percentage of CPU in use | Percent (%) | | FreeableMemory | Available RAM in the instance | Bytes | | ReadIOPS / WriteIOPS | Disk read/write operations per sec | Count/sec | | DatabaseConnections | Active connections to the DB | Count | ### 2.2 Custom RDS Metrics Enhance observability with application-specific data: | Metric Name | Description | Collection Interval | | --------------------- | ------------------------------------------- | ------------------- | | LoginsPerMinute | Number of successful user logins | 1 minute | | AvgQueryExecutionTime | Average time to execute SQL queries | 1 minute | | CacheHitRatio | Percentage of cache hits vs. total requests | 1 minute | Use the AWS SDK or CLI command `aws cloudwatch put-metric-data` to publish custom metrics from your application or monitoring scripts. ## 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](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/WhatIsCloudWatchLogs.html) for log monitoring *** ## Links and References * [AWS CloudWatch Metrics and Dimensions](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CW_Support_For_AWS.html) * [Amazon RDS Monitoring](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MonitoringOverview.html) * [CloudWatch Pricing](https://aws.amazon.com/cloudwatch/pricing/) * [AWS SDK for Go CloudWatch Guide](https://docs.aws.amazon.com/sdk-for-go/api/service/cloudwatch/)