Set default IMGPROXY_MAX_CLIENTS value to 2048; Allow unlimited connections

config/config.go

@@ -186,7 +186,7 @@ func Reset() {
 	KeepAliveTimeout = 10
 	DownloadTimeout = 5
 	Concurrency = runtime.NumCPU() * 2
-	MaxClients = 0
+	MaxClients = 2048
 
 	TTL = 3600
 	CacheControlPassthrough = false
@@ -534,8 +534,8 @@ func Configure() error {
 		return fmt.Errorf("Concurrency should be greater than 0, now - %d\n", Concurrency)
 	}
 
-	if MaxClients <= 0 {
-		MaxClients = Concurrency * 10
+	if MaxClients < 0 {
+		return fmt.Errorf("Concurrency should be greater than or equal 0, now - %d\n", MaxClients)
 	}
 
 	if TTL <= 0 {

docs/configuration.md

@@ -33,7 +33,7 @@ echo $(xxd -g 2 -l 64 -p /dev/random | tr -d '\n')
 * `IMGPROXY_KEEP_ALIVE_TIMEOUT`: the maximum duration (in seconds) to wait for the next request before closing the connection. When set to `0`, keep-alive is disabled. Default: `10`
 * `IMGPROXY_DOWNLOAD_TIMEOUT`: the maximum duration (in seconds) for downloading the source image. Default: `5`
 * `IMGPROXY_CONCURRENCY`: the maximum number of image requests to be processed simultaneously. Default: the number of CPU cores multiplied by two
-* `IMGPROXY_MAX_CLIENTS`: the maximum number of simultaneous active connections. Default: `IMGPROXY_CONCURRENCY * 10`
+* `IMGPROXY_MAX_CLIENTS`: the maximum number of simultaneous active connections. When set to `0`, connections number limitation is disabled. Default: `2048`
 * `IMGPROXY_TTL`: a duration (in seconds) sent via the `Expires` and `Cache-Control: max-age` HTTP headers. Default: `3600` (1 hour)
 * `IMGPROXY_CACHE_CONTROL_PASSTHROUGH`: when `true` and the source image response contains the `Expires` or `Cache-Control` headers, reuse those headers. Default: false
 * `IMGPROXY_SET_CANONICAL_HEADER`: when `true` and the source image has an `http` or `https` scheme, set a `rel="canonical"` HTTP header to the value of the source image URL. More details [here](https://developers.google.com/search/docs/advanced/crawling/consolidate-duplicate-urls#rel-canonical-header-method). Default: `false`

server.go

@@ -45,7 +45,10 @@ func startServer(cancel context.CancelFunc) (*http.Server, error) {
 	if err != nil {
 		return nil, fmt.Errorf("Can't start server: %s", err)
 	}
-	l = netutil.LimitListener(l, config.MaxClients)
+
+	if config.MaxClients > 0 {
+		l = netutil.LimitListener(l, config.MaxClients)
+	}
 
 	s := &http.Server{
 		Handler:        buildRouter(),