Metric - Callback Example

Code Source: https://github.com/gogf/examples/tree/main/observability/metric/callback

Description

This example demonstrates how to implement callback-based metric collection in GoFrame using OpenTelemetry and Prometheus integration. It shows how to:

• Create metrics with callback functions
• Automatically update metric values through callbacks
• Configure metric attributes
• Export metrics in Prometheus format

Structure

- `go.mod`: The Go module file for dependency management
- `go.sum`: The Go module checksums file
- `main.go`: The main application demonstrating callback-based metrics

Features

The example showcases the following features:

1. Callback-based Metrics

   • Automatic value updates
   • Custom callback functions
   • No manual update needed

2. Regular Metrics

   • Manual value updates
   • Direct control over values
   • Comparison with callback approach

3. Metric Configuration

   • Custom attributes
   • Help text
   • Units

Requirements

• Go 1.22 or higher
• Git
• GoFrame
• GoFrame OpenTelemetry Metric

Usage

1. Run the example:

   go run main.go

2. Access the metrics:

   # Using curl
   curl http://localhost:8000/metrics
   
   # Or open in browser
   http://localhost:8000/metrics

3. Example metrics output:

   # HELP goframe_metric_demo_counter This is a simple demo for Counter usage
   goframe_metric_demo_counter{const_attr_1="1"} 11
   
   # HELP goframe_metric_demo_observable_counter This is a simple demo for ObservableCounter usage
   goframe_metric_demo_observable_counter{const_attr_3="3"} 10

Implementation Details

The example demonstrates:

1. Creating metrics with callback functions
2. Automatic value updates through callbacks
3. Comparison between callback and manual updates
4. Proper metric configuration
5. Prometheus integration

Notes

• Callbacks are executed automatically by the metrics system
• No need for manual updates of callback-based metrics
• Callbacks should be lightweight and fast
• Consider thread safety in callbacks
• Proper cleanup is handled via defer
• Default port is 8000
• Metrics endpoint is at /metrics