first commit

plugins/telemetry/utils.go

@@ -0,0 +1,92 @@
+// Package telemetry provides Prometheus metrics collection and monitoring functionality
+// for the Bifrost HTTP service. This file contains the setup and configuration
+// for Prometheus metrics collection, including HTTP middleware and metric definitions.
+package telemetry
+
+import (
+	"log"
+	"math"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/valyala/fasthttp"
+)
+
+// getPrometheusLabelValues takes an array of expected label keys and a map of header values,
+// and returns an array of values in the same order as the keys, using empty string for missing values.
+func getPrometheusLabelValues(expectedLabels []string, headerValues map[string]string) []string {
+	values := make([]string, len(expectedLabels))
+	for i, label := range expectedLabels {
+		if value, exists := headerValues[label]; exists {
+			values[i] = value
+		} else {
+			values[i] = "" // Default empty value for missing labels
+		}
+	}
+	return values
+}
+
+// collectPrometheusKeyValues collects all metrics for a request including:
+// - Default metrics (path, method, status, request size)
+// - Custom prometheus headers (x-bf-prom-*)
+// Returns a map of all label values
+func collectPrometheusKeyValues(ctx *fasthttp.RequestCtx) map[string]string {
+	path := string(ctx.Path())
+	method := string(ctx.Method())
+
+	// Initialize with default metrics
+	labelValues := map[string]string{
+		"path":   path,
+		"method": method,
+	}
+
+	// Collect custom prometheus headers
+	ctx.Request.Header.All()(func(key, value []byte) bool {
+		keyStr := strings.ToLower(string(key))
+		if strings.HasPrefix(keyStr, "x-bf-prom-") {
+			labelName := strings.TrimPrefix(keyStr, "x-bf-prom-")
+			labelValues[labelName] = string(value)
+			ctx.SetUserValue(keyStr, string(value))
+		}
+		return true
+	})
+
+	return labelValues
+}
+
+// safeObserve safely records a value in a Prometheus histogram.
+// It prevents recording invalid values (negative or infinite) that could cause issues.
+func safeObserve(histogram *prometheus.HistogramVec, value float64, labels ...string) {
+	if value > 0 && value < math.MaxFloat64 {
+		metric, err := histogram.GetMetricWithLabelValues(labels...)
+		if err != nil {
+			log.Printf("Error getting metric with label values: %v", err)
+		} else {
+			metric.Observe(value)
+		}
+	}
+}
+
+// containsLabel checks if a string slice contains a specific label, ignoring differences
+// between underscores and hyphens. It checks for:
+// - Direct match
+// - Match after removing underscores
+// - Match after replacing hyphens with underscores
+// - Match after replacing underscores with hyphens
+func containsLabel(slice []string, label string) bool {
+	for _, s := range slice {
+		// Direct match
+		if s == label {
+			return true
+		}
+		// Match after replacing hyphens with underscores
+		if strings.ReplaceAll(s, "-", "_") == strings.ReplaceAll(label, "-", "_") {
+			return true
+		}
+		// Match after replacing underscores with hyphens
+		if strings.ReplaceAll(s, "_", "-") == strings.ReplaceAll(label, "_", "-") {
+			return true
+		}
+	}
+	return false
+}