Code cleanup of routes config loader and API server (#424)

Author: itzg

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
   release:
     uses: itzg/github-workflows/.github/workflows/go-with-releaser-image.yml@main
     with:
-      go-version: "1.24.4"
+      go-version-file: 'go.mod'
       enable-ghcr: true
     secrets:
       image-registry-username: ${{ secrets.DOCKERHUB_USERNAME }}

.github/workflows/test.yml

@@ -12,4 +12,4 @@ jobs:
   build:
     uses: itzg/github-workflows/.github/workflows/go-test.yml@main
     with:
-      go-version: "1.24.4"
+      go-version-file: 'go.mod'

README.md

@@ -178,7 +178,7 @@ The following shows a JSON file for routes config, where `default-server` can al
 }
 ```
 
-Sending a SIGHUP signal will cause mc-router to reload the routes config from disk.
+Sending a SIGHUP signal will cause mc-router to reload the routes config from disk. The file can also be watched for changes by setting `-routes-config-watch` or the env variable `ROUTES_CONFIG_WATCH` to "true".
 
 ## Auto Scale Allow/Deny List
 

cmd/mc-router/main.go

@@ -16,18 +16,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-type MetricsBackendConfig struct {
-	Influxdb struct {
-		Interval        time.Duration     `default:"1m"`
-		Tags            map[string]string `usage:"any extra tags to be included with all reported metrics"`
-		Addr            string
-		Username        string
-		Password        string
-		Database        string
-		RetentionPolicy string
-	}
-}
-
 type WebhookConfig struct {
 	Url         string `usage:"If set, a POST request that contains connection status notifications will be sent to this HTTP address"`
 	RequireUser bool   `default:"false" usage:"Indicates if the webhook will only be called if a user is connecting rather than just server list/ping"`
@@ -62,11 +50,11 @@ type Config struct {
 	DockerTimeout         int               `default:"0" usage:"Timeout configuration in seconds for the Docker integrations"`
 	DockerRefreshInterval int               `default:"15" usage:"Refresh interval in seconds for the Docker integrations"`
 	MetricsBackend        string            `default:"discard" usage:"Backend to use for metrics exposure/publishing: discard,expvar,influxdb,prometheus"`
-	UseProxyProtocol      bool              `default:"false" usage:"Send PROXY protocol to backend servers"`
-	ReceiveProxyProtocol  bool              `default:"false" usage:"Receive PROXY protocol from backend servers, by default trusts every proxy header that it receives, combine with -trusted-proxies to specify a list of trusted proxies"`
-	TrustedProxies        []string          `usage:"Comma delimited list of CIDR notation IP blocks to trust when receiving PROXY protocol"`
-	RecordLogins          bool              `default:"false" usage:"Log and generate metrics on player logins. Metrics only supported with influxdb or prometheus backend"`
-	MetricsBackendConfig  MetricsBackendConfig
+	MetricsBackendConfig  server.MetricsBackendConfig
+	UseProxyProtocol      bool     `default:"false" usage:"Send PROXY protocol to backend servers"`
+	ReceiveProxyProtocol  bool     `default:"false" usage:"Receive PROXY protocol from backend servers, by default trusts every proxy header that it receives, combine with -trusted-proxies to specify a list of trusted proxies"`
+	TrustedProxies        []string `usage:"Comma delimited list of CIDR notation IP blocks to trust when receiving PROXY protocol"`
+	RecordLogins          bool     `default:"false" usage:"Log and generate metrics on player logins. Metrics only supported with influxdb or prometheus backend"`
 	Routes                RoutesConfig
 	NgrokToken            string `usage:"If set, an ngrok tunnel will be established. It is HIGHLY recommended to pass as an environment variable."`
 	AutoScale             AutoScale
@@ -133,7 +121,7 @@ func main() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	metricsBuilder := NewMetricsBuilder(config.MetricsBackend, &config.MetricsBackendConfig)
+	metricsBuilder := server.NewMetricsBuilder(config.MetricsBackend, &config.MetricsBackendConfig)
 
 	downScalerEnabled := config.AutoScale.Down && (config.InKubeCluster || config.KubeConfig != "")
 	downScalerDelay, err := time.ParseDuration(config.AutoScale.DownAfter)
@@ -147,13 +135,13 @@ func main() {
 	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
 
 	if config.Routes.Config != "" {
-		err := server.RoutesConfig.ReadRoutesConfig(config.Routes.Config)
+		err := server.RoutesConfigLoader.Load(config.Routes.Config)
 		if err != nil {
 			logrus.WithError(err).Fatal("Unable to load routes from config file")
 		}
 
 		if config.Routes.ConfigWatch {
-			err := server.RoutesConfig.WatchForChanges(ctx)
+			err := server.RoutesConfigLoader.WatchForChanges(ctx)
 			if err != nil {
 				logrus.WithError(err).Fatal("Unable to watch for changes")
 			}
@@ -258,7 +246,7 @@ func main() {
 		case syscall.SIGHUP:
 			if config.Routes.Config != "" {
 				logrus.Info("Received SIGHUP, reloading routes config...")
-				if err := server.RoutesConfig.ReloadRoutesConfig(); err != nil {
+				if err := server.RoutesConfigLoader.Reload(); err != nil {
 					logrus.
 						WithError(err).
 						WithField("routesConfig", config.Routes.Config).

go.mod

@@ -1,8 +1,6 @@
 module github.com/itzg/mc-router
 
-go 1.24.0
-
-toolchain go1.24.4
+go 1.24.4
 
 require (
 	github.com/fsnotify/fsnotify v1.9.0

server/api_server.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"encoding/json"
 	"expvar"
 	"net/http"
 
@@ -9,11 +10,12 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-var apiRoutes = mux.NewRouter()
-
 func StartApiServer(apiBinding string) {
 	logrus.WithField("binding", apiBinding).Info("Serving API requests")
 
+	var apiRoutes = mux.NewRouter()
+	registerApiRoutes(apiRoutes)
+
 	apiRoutes.Path("/vars").Handler(expvar.Handler())
 
 	apiRoutes.Path("/metrics").Handler(promhttp.Handler())
@@ -23,3 +25,84 @@ func StartApiServer(apiBinding string) {
 			http.ListenAndServe(apiBinding, apiRoutes)).Error("API server failed")
 	}()
 }
+
+func registerApiRoutes(apiRoutes *mux.Router) {
+	apiRoutes.Path("/routes").Methods("GET").
+		HandlerFunc(routesListHandler)
+	apiRoutes.Path("/routes").Methods("POST").
+		HandlerFunc(routesCreateHandler)
+	apiRoutes.Path("/defaultRoute").Methods("POST").
+		HandlerFunc(routesSetDefault)
+	apiRoutes.Path("/routes/{serverAddress}").Methods("DELETE").HandlerFunc(routesDeleteHandler)
+}
+
+func routesListHandler(writer http.ResponseWriter, _ *http.Request) {
+	mappings := Routes.GetMappings()
+	bytes, err := json.Marshal(mappings)
+	if err != nil {
+		logrus.WithError(err).Error("Failed to marshal mappings")
+		writer.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	writer.Header().Set("Content-Type", "application/json")
+	_, err = writer.Write(bytes)
+	if err != nil {
+		logrus.WithError(err).Error("Failed to write response")
+	}
+}
+
+func routesDeleteHandler(writer http.ResponseWriter, request *http.Request) {
+	serverAddress := mux.Vars(request)["serverAddress"]
+	if serverAddress != "" {
+		if Routes.DeleteMapping(serverAddress) {
+			writer.WriteHeader(http.StatusOK)
+		} else {
+			writer.WriteHeader(http.StatusNotFound)
+		}
+		RoutesConfigLoader.SaveRoutes()
+	}
+}
+
+func routesCreateHandler(writer http.ResponseWriter, request *http.Request) {
+	var definition = struct {
+		ServerAddress string
+		Backend       string
+	}{}
+
+	//goland:noinspection GoUnhandledErrorResult
+	defer request.Body.Close()
+
+	decoder := json.NewDecoder(request.Body)
+	err := decoder.Decode(&definition)
+	if err != nil {
+		logrus.WithError(err).Error("Unable to get request body")
+		writer.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	Routes.CreateMapping(definition.ServerAddress, definition.Backend, EmptyScalerFunc, EmptyScalerFunc)
+	RoutesConfigLoader.SaveRoutes()
+	writer.WriteHeader(http.StatusCreated)
+}
+
+func routesSetDefault(writer http.ResponseWriter, request *http.Request) {
+	var body = struct {
+		Backend string
+	}{}
+
+	//goland:noinspection GoUnhandledErrorResult
+	defer request.Body.Close()
+
+	decoder := json.NewDecoder(request.Body)
+	err := decoder.Decode(&body)
+	if err != nil {
+		logrus.WithError(err).Error("Unable to parse request")
+		writer.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	Routes.SetDefaultRoute(body.Backend)
+	RoutesConfigLoader.SaveRoutes()
+	writer.WriteHeader(http.StatusOK)
+}

cmd/mc-router/metrics.go server/metrics.gocmd/mc-router/metrics.go renamed to server/metrics.go

@@ -1,4 +1,4 @@
-package main
+package server
 
 import (
 	"context"
@@ -13,14 +13,13 @@ import (
 	kitinflux "github.com/go-kit/kit/metrics/influx"
 	prometheusMetrics "github.com/go-kit/kit/metrics/prometheus"
 	influx "github.com/influxdata/influxdb1-client/v2"
-	"github.com/itzg/mc-router/server"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/sirupsen/logrus"
 )
 
 type MetricsBuilder interface {
-	BuildConnectorMetrics() *server.ConnectorMetrics
+	BuildConnectorMetrics() *ConnectorMetrics
 	Start(ctx context.Context) error
 }
 
@@ -31,6 +30,18 @@ const (
 	MetricsBackendDiscard    = "discard"
 )
 
+type MetricsBackendConfig struct {
+	Influxdb struct {
+		Interval        time.Duration     `default:"1m"`
+		Tags            map[string]string `usage:"any extra tags to be included with all reported metrics"`
+		Addr            string
+		Username        string
+		Password        string
+		Database        string
+		RetentionPolicy string
+	}
+}
+
 // NewMetricsBuilder creates a new MetricsBuilder based on the specified backend.
 // If the backend is not recognized, a discard builder is returned.
 // config can be nil if the backend is not influxdb.
@@ -57,9 +68,9 @@ func (b expvarMetricsBuilder) Start(ctx context.Context) error {
 	return nil
 }
 
-func (b expvarMetricsBuilder) BuildConnectorMetrics() *server.ConnectorMetrics {
+func (b expvarMetricsBuilder) BuildConnectorMetrics() *ConnectorMetrics {
 	c := expvarMetrics.NewCounter("connections")
-	return &server.ConnectorMetrics{
+	return &ConnectorMetrics{
 		Errors:                  expvarMetrics.NewCounter("errors").With("subsystem", "connector"),
 		BytesTransmitted:        expvarMetrics.NewCounter("bytes"),
 		ConnectionsFrontend:     c,
@@ -79,8 +90,8 @@ func (b discardMetricsBuilder) Start(ctx context.Context) error {
 	return nil
 }
 
-func (b discardMetricsBuilder) BuildConnectorMetrics() *server.ConnectorMetrics {
-	return &server.ConnectorMetrics{
+func (b discardMetricsBuilder) BuildConnectorMetrics() *ConnectorMetrics {
+	return &ConnectorMetrics{
 		Errors:                  discardMetrics.NewCounter(),
 		BytesTransmitted:        discardMetrics.NewCounter(),
 		ConnectionsFrontend:     discardMetrics.NewCounter(),
@@ -121,7 +132,7 @@ func (b *influxMetricsBuilder) Start(ctx context.Context) error {
 	return nil
 }
 
-func (b *influxMetricsBuilder) BuildConnectorMetrics() *server.ConnectorMetrics {
+func (b *influxMetricsBuilder) BuildConnectorMetrics() *ConnectorMetrics {
 	influxConfig := &b.config.Influxdb
 
 	metrics := kitinflux.New(influxConfig.Tags, influx.BatchPointsConfig{
@@ -132,7 +143,7 @@ func (b *influxMetricsBuilder) BuildConnectorMetrics() *server.ConnectorMetrics
 	b.metrics = metrics
 
 	c := metrics.NewCounter("mc_router_connections")
-	return &server.ConnectorMetrics{
+	return &ConnectorMetrics{
 		Errors:                  metrics.NewCounter("mc_router_errors"),
 		BytesTransmitted:        metrics.NewCounter("mc_router_transmitted_bytes"),
 		ConnectionsFrontend:     c.With("side", "frontend"),
@@ -155,13 +166,13 @@ func (b prometheusMetricsBuilder) Start(ctx context.Context) error {
 	return nil
 }
 
-func (b prometheusMetricsBuilder) BuildConnectorMetrics() *server.ConnectorMetrics {
+func (b prometheusMetricsBuilder) BuildConnectorMetrics() *ConnectorMetrics {
 	pcv = prometheusMetrics.NewCounter(promauto.NewCounterVec(prometheus.CounterOpts{
 		Namespace: "mc_router",
 		Name:      "errors",
 		Help:      "The total number of errors",
 	}, []string{"type"}))
-	return &server.ConnectorMetrics{
+	return &ConnectorMetrics{
 		Errors: pcv,
 		BytesTransmitted: prometheusMetrics.NewCounter(promauto.NewCounterVec(prometheus.CounterOpts{
 			Namespace: "mc_router",