Check if cgroup cpu limits are defined to get the number of CPUs

internal/ingress/controller/config/config.go

@@ -18,7 +18,6 @@ package config
 
 import (
 	"fmt"
-	"runtime"
 	"strconv"
 	"time"
 
@@ -28,6 +27,7 @@ import (
 
 	"k8s.io/ingress-nginx/internal/ingress"
 	"k8s.io/ingress-nginx/internal/ingress/defaults"
+	"k8s.io/ingress-nginx/internal/runtime"
 )
 
 const (

internal/ingress/controller/template/configmap.go

@@ -31,6 +31,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/ingress-nginx/internal/ingress/controller/config"
 	ing_net "k8s.io/ingress-nginx/internal/net"
+	"k8s.io/ingress-nginx/internal/runtime"
 )
 
 const (
@@ -45,6 +46,7 @@ const (
 	nginxStatusIpv4Whitelist = "nginx-status-ipv4-whitelist"
 	nginxStatusIpv6Whitelist = "nginx-status-ipv6-whitelist"
 	proxyHeaderTimeout       = "proxy-protocol-header-timeout"
+	workerProcesses          = "worker-processes"
 )
 
 var (
@@ -166,6 +168,16 @@ func ReadConfig(src map[string]string) config.Configuration {
 		delete(conf, nginxStatusIpv6Whitelist)
 	}
 
+	if val, ok := conf[workerProcesses]; ok {
+		to.WorkerProcesses = val
+
+		if val == "auto" {
+			to.WorkerProcesses = strconv.Itoa(runtime.NumCPU())
+		}
+
+		delete(conf, workerProcesses)
+	}
+
 	to.CustomHTTPErrors = filterErrors(errors)
 	to.SkipAccessLogURLs = skipUrls
 	to.WhitelistSourceRange = whiteList

internal/runtime/cpu.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2018 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 runtime
+
+import (
+	"io/ioutil"
+	"math"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+
+	libcontainercgroups "github.com/opencontainers/runc/libcontainer/cgroups"
+)
+
+// NumCPU returns the number of logical CPUs usable by the current process.
+// If CPU cgroups limits are configured, use cfs_quota_us / cfs_period_us
+// as formula
+//  https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
+func NumCPU() int {
+	cpus := runtime.NumCPU()
+
+	cgroupPath, err := libcontainercgroups.FindCgroupMountpoint("cpu")
+	if err != nil {
+		return cpus
+	}
+
+	cpuQuota := readCgroupFileToInt64(cgroupPath, "cpu.cfs_quota_us")
+	cpuPeriod := readCgroupFileToInt64(cgroupPath, "cpu.cfs_period_us")
+
+	if cpuQuota == -1 || cpuPeriod == -1 {
+		return cpus
+	}
+
+	return int(math.Ceil(float64(cpuQuota) / float64(cpuPeriod)))
+}
+
+func readCgroupFileToInt64(cgroupPath, cgroupFile string) int64 {
+	contents, err := ioutil.ReadFile(filepath.Join(cgroupPath, cgroupFile))
+	if err != nil {
+		return -1
+	}
+
+	strValue := strings.TrimSpace(string(contents))
+	if value, err := strconv.ParseInt(strValue, 10, 64); err == nil {
+		return value
+	}
+
+	return -1
+}