http_metrics.go

package main

import (
	"fmt"
	"github.com/espebra/filebin2/ds"
	"io"
	"net/http"
	"time"
)

func (h *HTTP) viewMetrics(w http.ResponseWriter, r *http.Request) {
	// If metrics are not enabled, exit early
	if !h.config.Metrics {
		http.Error(w, "Forbidden", http.StatusForbidden)
		return
	}

	// Check that authentication is enabled
	if h.config.MetricsAuth != "" {
		if h.config.MetricsAuth == "basic" {
			username, password, ok := r.BasicAuth()
			if ok == false || username != h.config.MetricsUsername || password != h.config.MetricsPassword {
				time.Sleep(3 * time.Second)
				w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
				http.Error(w, "Unauthorized", http.StatusUnauthorized)
				return
			}
		} else {
			// If an unknown authentication mechanism is specified,
			// reject the request.
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			return
		}
	}

	// Get metrics from the database
	err := h.dao.Metrics().UpdateMetrics(h.metrics)
	if err != nil {
		fmt.Printf("Unable to UpdateMetrics(): %s\n", err.Error())
		http.Error(w, "Errno 328", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/plain; version=0.0.4; charset=utf-8")
	w.Header().Set("Cache-Control", "max-age=1")

	type Data struct {
		Metrics  ds.Metrics
		Proxy    string
		ProxyURL string
	}
	h.metrics.Lock()
	defer h.metrics.Unlock()

	data := Data{}
	data.Metrics = *h.metrics
	data.ProxyURL = h.config.MetricsProxyURL

	// Fetch metrics from another URL
	if h.config.MetricsProxyURL != "" {
		// XXX: Add support for timeout
		resp, err := http.Get(h.config.MetricsProxyURL)
		if err != nil {
			fmt.Printf("Metrics proxy: Unable to GET %s: %s\n", h.config.MetricsProxyURL, err.Error())
		}
		defer resp.Body.Close()

		if err == nil {
			body, err := io.ReadAll(resp.Body)
			if err != nil {
				fmt.Printf("Metrics proxy: Unable to read body %s: %s\n", h.config.MetricsProxyURL, err.Error())
			}
			if resp.StatusCode == 200 {
				data.Proxy = string(body[:])
			} else {
				fmt.Printf("Metrics proxy: Got status code %d\n", resp.StatusCode)
			}
		}
	}

	if err := h.templates.ExecuteTemplate(w, "metrics", data); err != nil {
		fmt.Printf("Failed to execute template: %s\n", err.Error())
		http.Error(w, "Errno 302", http.StatusInternalServerError)
		return
	}
	return
}