Fix MaxWorkerOpenFiles calculation on high cores nodes (kubernetes#7107)

* Fix MaxWorkerOpenFiles calculation on high cores nodes

* Add e2e test for rlimit_nofile

* Fix doc for max-worker-open-files

docs/user-guide/nginx-configuration/configmap.md

@@ -454,7 +454,7 @@ _**default:**_ 16384
 ## max-worker-open-files
 
 Sets the [maximum number of files](http://nginx.org/en/docs/ngx_core_module.html#worker_rlimit_nofile) that can be opened by each worker process.
-The default of 0 means "max open files (system's limit) / [worker-processes](#worker-processes) - 1024".
+The default of 0 means "max open files (system's limit) - 1024".
 _**default:**_ 0
 
 ## map-hash-bucket-size

internal/ingress/controller/nginx.go

@@ -511,12 +511,7 @@ func (n NGINXController) generateTemplate(cfg ngx_config.Configuration, ingressC
 	if cfg.MaxWorkerOpenFiles == 0 {
 		// the limit of open files is per worker process
 		// and we leave some room to avoid consuming all the FDs available
-		wp, err := strconv.Atoi(cfg.WorkerProcesses)
-		klog.V(3).InfoS("Worker processes", "count", wp)
-		if err != nil {
-			wp = 1
-		}
-		maxOpenFiles := (rlimitMaxNumFiles() / wp) - 1024
+		maxOpenFiles := rlimitMaxNumFiles() - 1024
 		klog.V(3).InfoS("Maximum number of open file descriptors", "value", maxOpenFiles)
 		if maxOpenFiles < 1024 {
 			// this means the value of RLIMIT_NOFILE is too low.

test/e2e/settings/global_options.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package settings
+
+import (
+	"fmt"
+	"strings"
+	"syscall"
+
+	"github.com/onsi/ginkgo"
+	"k8s.io/ingress-nginx/test/e2e/framework"
+)
+
+var _ = framework.IngressNginxDescribe("global-options", func() {
+	f := framework.NewDefaultFramework("global-options")
+
+	ginkgo.It("should have worker_rlimit_nofile option", func() {
+		f.WaitForNginxConfiguration(func(server string) bool {
+			return strings.Contains(server, fmt.Sprintf("worker_rlimit_nofile %d;", rlimitMaxNumFiles()-1024))
+
+		})
+	})
+
+	ginkgo.It("should have worker_rlimit_nofile option and be independent on amount of worker processes", func() {
+		f.SetNginxConfigMapData(map[string]string{
+			"worker-processes": "11",
+		})
+
+		f.WaitForNginxConfiguration(func(server string) bool {
+			return strings.Contains(server, "worker_processes 11;") &&
+				strings.Contains(server, fmt.Sprintf("worker_rlimit_nofile %d;", rlimitMaxNumFiles()-1024))
+		})
+	})
+})
+
+// rlimitMaxNumFiles returns hard limit for RLIMIT_NOFILE
+func rlimitMaxNumFiles() int {
+	var rLimit syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		return 0
+	}
+	return int(rLimit.Max)
+}