Feat/fileserver (#60)

* cleanup code for URL type

* fix makefile for trace mode

* refactor, merge Entry, RawEntry and Route into one. 

* Implement fileserver.

* refactor: rename HTTPRoute to ReverseProxyRoute to avoid confusion

* refactor: move metrics logger to middleware package

- fix prometheus metrics for load balanced routes
  - route will now fail when health monitor fail to start

* fix extra output of ls-* commands by defer initializaing stuff, speed up start time

* add test for path traversal attack, small fix on FileServer.Start method

* rename rule.on.bypass to pass

* refactor and fixed map-to-map  deserialization

* updated route loading logic

* schemas: add "add_prefix" option to modify_request middleware


* updated route JSONMarshalling

---------

Co-authored-by: yusing <yusing@6uo.me>

internal/net/http/middleware/metrics_logger/metrics_logger.go

@@ -0,0 +1,44 @@
+package metricslogger
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/metrics"
+)
+
+type MetricsLogger struct {
+	ServiceName string `json:"service_name"`
+}
+
+func NewMetricsLogger(serviceName string) *MetricsLogger {
+	return &MetricsLogger{serviceName}
+}
+
+func (m *MetricsLogger) GetHandler(next http.Handler) http.HandlerFunc {
+	return func(rw http.ResponseWriter, req *http.Request) {
+		m.ServeHTTP(rw, req, next.ServeHTTP)
+	}
+}
+
+func (m *MetricsLogger) ServeHTTP(rw http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
+	visitorIP, _, err := net.SplitHostPort(req.RemoteAddr)
+	if err != nil {
+		visitorIP = req.RemoteAddr
+	}
+
+	// req.RemoteAddr had been modified by middleware (if any)
+	lbls := &metrics.HTTPRouteMetricLabels{
+		Service: m.ServiceName,
+		Method:  req.Method,
+		Host:    req.Host,
+		Visitor: visitorIP,
+		Path:    req.URL.Path,
+	}
+
+	next.ServeHTTP(newHTTPMetricLogger(rw, lbls), req)
+}
+
+func (m *MetricsLogger) ResetMetrics() {
+	metrics.GetRouteMetrics().UnregisterService(m.ServiceName)
+}

internal/net/http/middleware/metrics_logger/metrics_response_writer.go

@@ -0,0 +1,47 @@
+package metricslogger
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/yusing/go-proxy/internal/metrics"
+)
+
+type httpMetricLogger struct {
+	http.ResponseWriter
+	timestamp time.Time
+	labels    *metrics.HTTPRouteMetricLabels
+}
+
+// WriteHeader implements http.ResponseWriter.
+func (l *httpMetricLogger) WriteHeader(status int) {
+	l.ResponseWriter.WriteHeader(status)
+	duration := time.Since(l.timestamp)
+	go func() {
+		m := metrics.GetRouteMetrics()
+		m.HTTPReqTotal.Inc()
+		m.HTTPReqElapsed.With(l.labels).Set(float64(duration.Milliseconds()))
+
+		// ignore 1xx
+		switch {
+		case status >= 500:
+			m.HTTP5xx.With(l.labels).Inc()
+		case status >= 400:
+			m.HTTP4xx.With(l.labels).Inc()
+		case status >= 200:
+			m.HTTP2xx3xx.With(l.labels).Inc()
+		}
+	}()
+}
+
+func (l *httpMetricLogger) Unwrap() http.ResponseWriter {
+	return l.ResponseWriter
+}
+
+func newHTTPMetricLogger(w http.ResponseWriter, labels *metrics.HTTPRouteMetricLabels) *httpMetricLogger {
+	return &httpMetricLogger{
+		ResponseWriter: w,
+		timestamp:      time.Now(),
+		labels:         labels,
+	}
+}