Metrics working

.gitignore

@@ -2,3 +2,4 @@
 *.key
 bin/
 data.json
+*.json

cmd/domain-router/main.go

@@ -101,6 +101,10 @@ func configureMiddleware(config *domainrouter.Config) middleware.Middleware {
 		middlewares = append(middlewares, middleware.RequestLogger)
 	}
 
+	metrics := middleware.NewMetrics(512, 1*time.Minute, "tmp_metrics.json")
+	go metrics.Manage()
+	middlewares = append(middlewares, metrics.RequestMetrics)
+
 	pipeline := middleware.Pipeline(middlewares...)
 	return pipeline
 }

config.go

@@ -23,6 +23,7 @@ type Config struct {
 		Remotes []string          `yaml:"remotes"`
 		Domains []string          `yaml:"domains"`
 		Secure  bool              `yaml:"secure"`
+		Rewrite map[string]string `yaml:"rewrite"`
 	} `yaml:"hosts"`
 	RateLimit struct {
 		Enabled       bool   `yaml:"enabled"`

config.yaml

@@ -53,9 +53,9 @@ hosts:
 
   - remotes:
       - localhost
-    port: 8282
+    port: 8080
     domains:
-      - private.localhost
+      - api.hitstar.localhost
 
   - remotes:
       - localhost
@@ -63,23 +63,11 @@ hosts:
     domains:
       - hitstar.localhost
       - hipstar.localhost
+    rewrite:
+      "/api": api.hitstar.localhost
 
   - remotes:
       - 127.0.0.1
     port: 46009
     domains:
       - chat.localhost
-
-  - remotes:
-      - localhost
-    port: 8080
-    domains:
-      - gorilla.localhost
-
-  - remotes: 
-      - www.google.com
-    port: 443
-    # Uses https under the hood to communicate with the remote host
-    secure: true
-    domains:
-      - google.localhost

middleware/logging.go

@@ -22,6 +22,7 @@ func RequestLogger(next http.Handler) http.Handler {
 			Str("uri", r.RequestURI).
 			Str("method", r.Method).
 			Str("uuid", uuid).
+			Str("remote_address", r.RemoteAddr).
 			Msg("Received Request")
 
 		next.ServeHTTP(lrw, r)

middleware/metrics.go

@@ -0,0 +1,131 @@
+package middleware
+
+import (
+	"cmp"
+	"encoding/json"
+	"net/http"
+	"os"
+	"slices"
+	"strings"
+	"time"
+
+	"github.com/rs/zerolog/log"
+)
+
+type Metrics struct {
+	c               chan RequestMetric
+	endpointMetrics []EndpointMetrics
+	ticker          *time.Ticker
+	file            string
+}
+
+type EndpointMetrics struct {
+	Host             string
+	Endpoint         string
+	AbsoluteDuration time.Duration
+	Calls            uint64
+}
+
+type RequestMetric struct {
+	Start  time.Time
+	Stop   time.Time
+	Host   string
+	Method string
+	Uri    string
+	Status int
+	Size   int
+}
+
+func NewMetrics(bufferSize int, flushTimeout time.Duration, file string) *Metrics {
+	return &Metrics{
+		c:      make(chan RequestMetric, bufferSize),
+		ticker: time.NewTicker(flushTimeout),
+		file:   file,
+	}
+}
+
+func (m *Metrics) RequestMetrics(next http.Handler) http.Handler {
+	log.Info().Msg("Enabling Request Metrics")
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		rm := RequestMetric{
+			Start:  start,
+			Host:   r.Host,
+			Method: r.Method,
+			Uri:    r.URL.Path,
+		}
+
+		log.Trace().Any("request_metric", rm).Msg("RequestMetric created")
+		next.ServeHTTP(w, r)
+		rm.Stop = time.Now()
+		log.Trace().Any("request_metric", rm).Msg("RequestMetric finished")
+
+		m.c <- rm
+	})
+}
+
+func (m *Metrics) Manage() {
+	for {
+		select {
+		case rm := <-m.c:
+			m.calculateDuration(rm)
+		case <-m.ticker.C:
+			m.Flush()
+		}
+	}
+}
+
+func (m *Metrics) calculateDuration(rm RequestMetric) {
+	duration := rm.Stop.Sub(rm.Start)
+
+	// TODO: Replace this with a hash probably
+	index := slices.IndexFunc(m.endpointMetrics, func(e EndpointMetrics) bool {
+		if strings.EqualFold(e.Host, rm.Host) && strings.EqualFold(e.Endpoint, rm.Uri) {
+			return true
+		}
+		return false
+	})
+
+	var in EndpointMetrics
+	if index >= 0 {
+		in = m.endpointMetrics[index]
+	} else {
+		in = EndpointMetrics{
+			Host:             rm.Host,
+			Endpoint:         rm.Uri,
+			AbsoluteDuration: time.Duration(0),
+			Calls:            0,
+		}
+	}
+
+	in.AbsoluteDuration += duration
+	in.Calls += 1
+
+	if index >= 0 {
+		m.endpointMetrics[index] = in
+	} else {
+		m.endpointMetrics = append(m.endpointMetrics, in)
+	}
+}
+
+func (m *Metrics) Flush() {
+	file, err := os.Create(m.file)
+	if err != nil {
+		log.Error().Err(err).Str("file", m.file).Msg("Could not open file for flushing")
+		return
+	}
+
+	a := make([]EndpointMetrics, len(m.endpointMetrics))
+	copy(a, m.endpointMetrics)
+	slices.SortStableFunc(a, func(e1 EndpointMetrics, e2 EndpointMetrics) int {
+		return cmp.Compare(e1.Calls, e2.Calls)
+	})
+
+	err = json.NewEncoder(file).Encode(a)
+	if err != nil {
+		log.Error().Err(err).Str("file", m.file).Msg("Could not json Encode to file")
+		return
+	}
+
+	log.Info().Str("file", m.file).Int("count", len(a)).Msg("Completed Metrics flush")
+}

router.go

@@ -28,13 +28,23 @@ type Host struct {
 	Remotes  []string
 	Secure   bool
 	Current  *atomic.Uint32
+	Rewrites map[string]*Host
 }
 
 func New(config *Config, client *http.Client) Router {
 	m := make(map[string]Host)
 	for _, host := range config.Hosts {
 		for _, domain := range host.Domains {
-			m[domain] = Host{host.Port, host.Remotes, host.Secure, &atomic.Uint32{}}
+			curr := Host{host.Port, host.Remotes, host.Secure, &atomic.Uint32{}, make(map[string]*Host)}
+			m[domain] = curr
+
+			for subUrl, rewriteHost := range host.Rewrite {
+				rewrite, ok := m[rewriteHost]
+				if !ok {
+					panic("WIP: Rewrite location has to be defined before rewrite")
+				}
+				curr.Rewrites[subUrl] = &rewrite
+			}
 		}
 	}
 
@@ -87,6 +97,31 @@ func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	for subUrl, rewriteHost := range host.Rewrites {
+		parts := strings.Split(subUrl, "/")
+		requestParts := strings.Split(r.URL.Path, "/")
+
+		for i, part := range parts {
+			if !strings.EqualFold(part, requestParts[i]) {
+				break
+			}
+		}
+
+		slicedPath := "/" + strings.Join(requestParts[len(parts):], "/")
+
+		log.Info().
+			Str("old_host", strings.Join(host.Remotes, ", ")).
+			Str("new_host", strings.Join(rewriteHost.Remotes, ", ")).
+			Str("sub_url", subUrl).
+			Str("requested_path", r.URL.Path).
+			Str("new_path", slicedPath).
+			Msg("Rewriting matched url path to different remote")
+		
+		r.URL.Path = slicedPath
+		host = *rewriteHost
+		break
+	}
+
 	remote := host.Remotes[host.Current.Load()]
 	go router.roundRobin(&host)