use apiMiddleware for better metrics

handler.go

@@ -9,10 +9,11 @@ import (
 	"net/http"
 	"net/url"
 
+	"github.com/prometheus/client_golang/prometheus"
+
 	"github.com/google/uuid"
 	"github.com/gorilla/mux"
 	"github.com/minio/minio-go/v7"
-	"github.com/prometheus/client_golang/prometheus"
 )
 
 func (c *Config) HealthCheckHandler(w http.ResponseWriter, _ *http.Request) {
@@ -50,9 +51,7 @@ func (c *Config) DownloadHandler(w http.ResponseWriter, r *http.Request) {
 
 	// only return checksum when called in sum mode
 	if sumMode {
-		traceLog(c.logger, "sum "+object.Key)
 		metricObjectAction.With(prometheus.Labels{"action": "sum"}).Inc()
-
 		_, httpResponseError := fmt.Fprintf(w, "%s  %s\n", object.UserMetadata[ChecksumMetadataFieldName], filename)
 		if httpResponseError != nil {
 			w.WriteHeader(http.StatusInternalServerError)
@@ -70,7 +69,6 @@ func (c *Config) DownloadHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	traceLog(c.logger, "download "+object.Key)
 	metricObjectAction.With(prometheus.Labels{"action": "download"}).Inc()
 
 	if _, copyError := io.Copy(w, reader); err != nil {
@@ -81,7 +79,6 @@ func (c *Config) DownloadHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func (c *Config) UploadHandler(w http.ResponseWriter, r *http.Request) {
-	fmt.Printf("%#v\n", r.Header)
 	vars := mux.Vars(r)
 	filename, ok := vars["filename"]
 	filename = url.QueryEscape(filename)
@@ -114,7 +111,7 @@ func (c *Config) UploadHandler(w http.ResponseWriter, r *http.Request) {
 	metadata[ChecksumMetadataFieldName] = hex.EncodeToString(sha512SumGenerator.Sum(nil))
 
 	id := uuid.New()
-	object, err := c.minioClient.PutObject(r.Context(), p.S3BucketName, id.String()+"/"+filename, buf, r.ContentLength, minio.PutObjectOptions{
+	_, err = c.minioClient.PutObject(r.Context(), p.S3BucketName, id.String()+"/"+filename, buf, r.ContentLength, minio.PutObjectOptions{
 		ContentType:  selectContentType(filename),
 		UserMetadata: metadata,
 	})
@@ -126,8 +123,6 @@ func (c *Config) UploadHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	metricObjectSize.Observe(float64(r.ContentLength))
-
-	traceLog(c.logger, "upload "+object.Key)
 	metricObjectAction.With(prometheus.Labels{"action": "upload"}).Inc()
 
 	// generate download link

helper.go

@@ -6,8 +6,30 @@ import (
 	"net/http"
 	"path"
 	"runtime"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
 )
 
+// apiMiddleware - logging and metrics for api endpoints
+func apiMiddleware(handler http.HandlerFunc, logger *log.Logger, endpointName string) http.HandlerFunc {
+	if logger == nil {
+		logger = log.Default()
+	}
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		metricEndpointRequests.With(prometheus.Labels{"endpoint": endpointName}).Inc()
+		start := time.Now()
+
+		// serve http request
+		handler.ServeHTTP(w, r)
+		duration := time.Since(start)
+		metricOperationDuration.With(prometheus.Labels{"endpoint": endpointName}).Observe(duration.Seconds())
+
+		logger.Printf("%v %v %v", r.Method, r.RequestURI, duration)
+	}
+	return fn
+}
+
 // selectContentType - parse file extension and determine content type
 func selectContentType(filename string) string {
 	extension := path.Ext(filename)

main.go

@@ -45,13 +45,26 @@ var (
 		Help:      "Actions applied to objects",
 	}, []string{"action"})
 
+	metricEndpointRequests = promauto.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: "transfer",
+		Name:      "endpoint_requests",
+		Help:      "HTTP endpoint requests",
+	}, []string{"endpoint"})
+
 	metricObjectSize = promauto.NewHistogram(prometheus.HistogramOpts{
 		Namespace: "transfer",
 		Name:      "object_size_bytes",
 		Help:      "Uploaded objects by size",
 		Buckets:   []float64{1 * KB, 10 * KB, 100 * KB, 1 * MB, 10 * MB, 100 * MB, 300 * MB, 600 * MB, 900 * MB},
 	})
 
+	metricOperationDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Namespace: "transfer",
+		Name:      "operation_duration",
+		Help:      "duration per endpoint",
+		Buckets:   []float64{0.01, 0.05, 0.1, 0.2, 0.4, 1, 2, 4, 8, 10, 20},
+	}, []string{"endpoint"})
+
 	// declare initial state as unhealthy
 	backendState = StateUnhealthy
 )
@@ -151,9 +164,9 @@ func main() {
 	}
 
 	applicationRouter := mux.NewRouter()
-	applicationRouter.HandleFunc("/{id}/{filename}", c.DownloadHandler).Methods(http.MethodGet)
-	applicationRouter.HandleFunc("/{id}/{filename}/{sum:sum}", c.DownloadHandler).Methods(http.MethodGet)
-	applicationRouter.HandleFunc("/{filename}", c.UploadHandler).Methods(http.MethodPut)
+	applicationRouter.HandleFunc("/{filename}", apiMiddleware(c.UploadHandler, c.logger, "upload")).Methods(http.MethodPut)
+	applicationRouter.HandleFunc("/{id}/{filename}", apiMiddleware(c.DownloadHandler, c.logger, "download")).Methods(http.MethodGet)
+	applicationRouter.HandleFunc("/{id}/{filename}/{sum:sum}", apiMiddleware(c.DownloadHandler, c.logger, "sum")).Methods(http.MethodGet)
 
 	metricsRouter := mux.NewRouter()
 	metricsRouter.Handle("/metrics", promhttp.Handler()).Methods(http.MethodGet)