Add limit on number of horizon requests in flight

stellar · Mar 13, 2024 · afac1df · afac1df
1 parent 4b0b078
commit afac1df
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Showing 4 changed files with 26 additions and 10 deletions.
diff --git a/services/horizon/internal/app.go b/services/horizon/internal/app.go
@@ -532,6 +532,7 @@ func (a *App) init() error {
 		SSEUpdateFrequency:       a.config.SSEUpdateFrequency,
 		StaleThreshold:           a.config.StaleThreshold,
 		ConnectionTimeout:        a.config.ConnectionTimeout,
+		MaxConcurrentRequests:    a.config.MaxConcurrentRequests,
 		MaxHTTPRequestSize:       a.config.MaxHTTPRequestSize,
 		NetworkPassphrase:        a.config.NetworkPassphrase,
 		MaxPathLength:            a.config.MaxPathLength,

diff --git a/services/horizon/internal/config.go b/services/horizon/internal/config.go
@@ -39,11 +39,12 @@ type Config struct {
 	SSEUpdateFrequency time.Duration
 	ConnectionTimeout  time.Duration
 	// MaxHTTPRequestSize is the maximum allowed request payload size
-	MaxHTTPRequestSize uint
-	RateQuota          *throttled.RateQuota
-	FriendbotURL       *url.URL
-	LogLevel           logrus.Level
-	LogFile            string
+	MaxHTTPRequestSize    uint
+	RateQuota             *throttled.RateQuota
+	MaxConcurrentRequests uint
+	FriendbotURL          *url.URL
+	LogLevel              logrus.Level
+	LogFile               string
 
 	// MaxPathLength is the maximum length of the path returned by `/paths` endpoint.
 	MaxPathLength uint

diff --git a/services/horizon/internal/flags.go b/services/horizon/internal/flags.go
@@ -68,7 +68,8 @@ const (
 	// StellarTestnet is a constant representing the Stellar test network
 	StellarTestnet = "testnet"
 
-	defaultMaxHTTPRequestSize = uint(200 * 1024)
+	defaultMaxConcurrentRequests = 1000
+	defaultMaxHTTPRequestSize    = uint(200 * 1024)
 )
 
 var (
@@ -445,6 +446,15 @@ func Flags() (*Config, support.ConfigOptions) {
 			Usage:          "sets the limit on the maximum allowed http request payload size, default is 200kb, to disable the limit check, set to 0, only do so if you acknowledge the implications of accepting unbounded http request payload sizes.",
 			UsedInCommands: ApiServerCommands,
 		},
+		&support.ConfigOption{
+			Name:        "max-concurrent-requests",
+			ConfigKey:   &config.MaxConcurrentRequests,
+			OptType:     types.Uint,
+			FlagDefault: defaultMaxConcurrentRequests,
+			Usage: "sets the limit on the maximum number of concurrent http requests, default is 1000, to disable the limit set to 0. " +
+				"If Horizon receives a request which would exceed the limit of concurrent http requests, Horizon will respond with a 429 status code.",
+			UsedInCommands: ApiServerCommands,
+		},
 		&support.ConfigOption{
 			Name:        "per-hour-rate-limit",
 			ConfigKey:   &config.RateQuota,

diff --git a/services/horizon/internal/httpx/router.go b/services/horizon/internal/httpx/router.go
@@ -28,10 +28,11 @@ import (
 )
 
 type RouterConfig struct {
-	DBSession        db.SessionInterface
-	PrimaryDBSession db.SessionInterface
-	TxSubmitter      *txsub.System
-	RateQuota        *throttled.RateQuota
+	DBSession             db.SessionInterface
+	PrimaryDBSession      db.SessionInterface
+	TxSubmitter           *txsub.System
+	RateQuota             *throttled.RateQuota
+	MaxConcurrentRequests uint
 
 	BehindCloudflare         bool
 	BehindAWSLoadBalancer    bool
@@ -90,6 +91,9 @@ func (r *Router) addMiddleware(config *RouterConfig,
 		BehindAWSLoadBalancer: config.BehindAWSLoadBalancer,
 	}))
 	r.Use(loggerMiddleware(serverMetrics))
+	if config.MaxConcurrentRequests > 0 {
+		r.Use(chimiddleware.Throttle(int(config.MaxConcurrentRequests)))
+	}
 	r.Use(timeoutMiddleware(config.ConnectionTimeout))
 	if config.MaxHTTPRequestSize > 0 {
 		r.Use(func(handler http.Handler) http.Handler {