To create a dashboard or visualization tool for expvar metrics in Go, you can follow these steps:
Install a suitable web framework: Choose a web framework like gin or echo to handle HTTP requests and routing. You can install them using go get command:
go get -u github.com/gin-gonic/gin
Import necessary packages: Import the required packages for your application:
import (
"expvar"
"github.com/gin-gonic/gin"
"net/http"
)
Create a custom Handler to expose expvar metrics: Define a custom handler function that will handle the request to expose expvar metrics:
func ExpvarHandler() gin.HandlerFunc {
return func(c *gin.Context) {
expvar.Handler().ServeHTTP(c.Writer, c.Request)
}
}
Set up your HTTP server: Configure your HTTP server using the chosen web framework and set up routes for the metrics endpoint:
func main() {
router := gin.Default()
// Set up the expvar handler route
router.GET("/metrics", ExpvarHandler())
// Run the HTTP server
router.Run(":8080")
}
Add instrumented variables: In your Go code, use expvar package functions to create and update expvar variables:
package main
import (
"expvar"
"time"
)
var (
totalRequests = expvar.NewInt("total_requests")
requestDurations = expvar.NewFloat("request_durations")
)
func handleRequest(c *gin.Context) {
// Record request
totalRequests.Add(1)
// Simulate some work
time.Sleep(time.Second)
// Record request duration
requestDurations.Set(float64(time.Second))
// Handle request
c.String(http.StatusOK, "Hello, World!")
}
Run your application: Compile and run your application using the go run command:
go run main.go
Access the metrics dashboard: Navigate to http://localhost:8080/metrics, or the appropriate address, in your web browser to access the expvar metrics dashboard.
Keep in mind that this is a simple example to get you started. You can customize and extend it further based on your specific requirements, such as adding more expvar variables, formatting the metrics display, and integrating additional visualization tools.