feat(HMS-4757): measure header and body request sizes

This change add metrics to retrieve the size for header and body requests, by adding the necessary changes to metrics structure, and the behavior to store the metrics at the metrics middleware. https://issues.redhat.com/browse/HMS-4757 Signed-off-by: Alejandro Visiedo <[email protected]>
podengo-project · Sep 26, 2024 · 3713b2a · 3713b2a
1 parent 7a68d7d
commit 3713b2a
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Showing 3 changed files with 44 additions and 1 deletion.
diff --git a/internal/infrastructure/middleware/metrics.go b/internal/infrastructure/middleware/metrics.go
@@ -2,11 +2,14 @@ package middleware
 
 import (
 	"errors"
+	"log/slog"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/labstack/echo/v4"
 	echo_middleware "github.com/labstack/echo/v4/middleware"
+	"github.com/podengo-project/idmsvc-backend/internal/infrastructure/context"
 	"github.com/podengo-project/idmsvc-backend/internal/metrics"
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -40,6 +43,8 @@ func MetricsMiddlewareWithConfig(config *MetricsConfig) echo.MiddlewareFunc {
 
 			err := next(ctx)
 
+			logger := context.LogFromCtx(ctx.Request().Context())
+
 			method := ctx.Request().Method
 			path := MatchedRoute(ctx)
 			status := ctx.Response().Status
@@ -50,6 +55,25 @@ func MetricsMiddlewareWithConfig(config *MetricsConfig) echo.MiddlewareFunc {
 				status = httpErr.Code
 			}
 			statusStr := strconv.Itoa(status)
+			headerBuf := strings.Builder{}
+			headerSize := 0.0
+			if errHeaderBuf := ctx.Request().Header.Write(&headerBuf); errHeaderBuf == nil {
+				headerSize = float64(len(headerBuf.String()))
+				config.Metrics.HTTPRequestHeaderSize.WithLabelValues(statusStr, method, path).Observe(headerSize)
+			} else {
+				logger.Warn("writing headers in string buffer",
+					slog.String("err", errHeaderBuf.Error()),
+				)
+			}
+			bodySize := float64(ctx.Request().ContentLength)
+			config.Metrics.HTTPRequestBodySize.WithLabelValues(statusStr, method, path).Observe(bodySize)
+			logger.Debug("measured request size",
+				slog.String("status", statusStr),
+				slog.String("method", method),
+				slog.String("path", path),
+				slog.Float64("header_size", headerSize),
+				slog.Float64("body_size", bodySize),
+			)
 
 			config.Metrics.HTTPRequestDuration.WithLabelValues(statusStr, method, path).Observe(time.Since(start).Seconds())
 

diff --git a/internal/infrastructure/middleware/metrics_test.go b/internal/infrastructure/middleware/metrics_test.go
@@ -69,6 +69,7 @@ func TestMetricsMiddlewareWithConfigCreation(t *testing.T) {
 	}
 
 	e := echo.New()
+	e.Use(ContextLogConfig(&LogConfig{}))
 	m := MetricsMiddlewareWithConfig(config)
 	e.Use(m)
 	path := "/api/idmsvc/v1/domains"

diff --git a/internal/metrics/metrics.go b/internal/metrics/metrics.go
@@ -13,8 +13,12 @@ const (
 
 // Metrics holds all the Prometheus metrics for the application
 type Metrics struct {
-	// HTTPRequestDuration is a histogram that measures the duration of HTTP requests
+	// HTTPRequestDuration is a histogram that measures the duration of the HTTP requests
 	HTTPRequestDuration *prometheus.HistogramVec
+	// HTTPRequestHeaderSize is a histogram that measures the size of the HTTP request headers.
+	HTTPRequestHeaderSize *prometheus.HistogramVec
+	// HTTPRequestBodySize is a histogram that measures the size of the HTTP request bodys.
+	HTTPRequestBodySize *prometheus.HistogramVec
 
 	reg *prometheus.Registry
 }
@@ -37,6 +41,20 @@ func NewMetrics(reg *prometheus.Registry) *Metrics {
 			Help:      "Duration of HTTP requests",
 			Buckets:   prometheus.ExponentialBuckets(0.0005, 2, 20),
 		}, []string{"status", "method", "path"}),
+		HTTPRequestHeaderSize: promauto.With(reg).NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: NameSpace,
+			Name:      "http_request_header_size",
+			Help:      "Size of the HTTP request headers",
+			// Bucket limited to 32KB
+			Buckets: []float64{1024, 2 * 1024, 4 * 1024, 8 * 1024, 16 * 1024, 32 * 1024},
+		}, []string{"status", "method", "path"}),
+		HTTPRequestBodySize: promauto.With(reg).NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: NameSpace,
+			Name:      "http_request_body_size",
+			Help:      "Size of the HTTP request bodies",
+			// Bucket limited to 128KB
+			Buckets: []float64{1024, 2 * 1024, 4 * 1024, 8 * 1024, 16 * 1024, 32 * 1024, 64 * 1024, 128 * 1024},
+		}, []string{"status", "method", "path"}),
 	}
 
 	reg.MustRegister(collectors.NewBuildInfoCollector())