Exposed a new API to get number of CPU Cores on a Node

cns/api.go

@@ -18,6 +18,7 @@ const (
 	GetIPAddressUtilizationPath = "/network/ip/utilization"
 	GetUnhealthyIPAddressesPath = "/network/ipaddresses/unhealthy"
 	GetHealthReportPath         = "/network/health"
+	NumberOfCPUCoresPath        = "/hostcpucores"
 	V1Prefix                    = "/v0.1"
 	V2Prefix                    = "/v0.2"
 )
@@ -139,6 +140,12 @@ type Response struct {
 	Message    string
 }
 
+// NumOfCPUCoresResponse describes num of cpu cores present on host.
+type NumOfCPUCoresResponse struct {
+	Response      Response
+	NumOfCPUCores int
+}
+
 // OptionMap describes generic options that can be passed to CNS.
 type OptionMap map[string]interface{}
 

cns/restserver/api.go

@@ -21,6 +21,7 @@ const (
 	UnknownContainerID           = 18
 	UnsupportedOrchestratorType  = 19
 	DockerContainerNotSpecified  = 20
+	UnsupportedVerb              = 21
 	UnexpectedError              = 99
 )
 

cns/restserver/restserver.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"runtime"
 	"sync"
 	"time"
 
@@ -157,6 +158,7 @@ func (service *HTTPRestService) Start(config *common.ServiceConfig) error {
 	listener.AddHandler(cns.DetachContainerFromNetwork, service.detachNetworkContainerFromNetwork)
 	listener.AddHandler(cns.CreateHnsNetworkPath, service.createHnsNetwork)
 	listener.AddHandler(cns.DeleteHnsNetworkPath, service.deleteHnsNetwork)
+	listener.AddHandler(cns.NumberOfCPUCoresPath, service.getNumberOfCPUCores)
 
 	// handlers for v0.2
 	listener.AddHandler(cns.V2Prefix+cns.SetEnvironmentPath, service.setEnvironment)
@@ -177,6 +179,7 @@ func (service *HTTPRestService) Start(config *common.ServiceConfig) error {
 	listener.AddHandler(cns.V2Prefix+cns.DetachContainerFromNetwork, service.detachNetworkContainerFromNetwork)
 	listener.AddHandler(cns.V2Prefix+cns.CreateHnsNetworkPath, service.createHnsNetwork)
 	listener.AddHandler(cns.V2Prefix+cns.DeleteHnsNetworkPath, service.deleteHnsNetwork)
+	listener.AddHandler(cns.V2Prefix+cns.NumberOfCPUCoresPath, service.getNumberOfCPUCores)
 
 	log.Printf("[Azure CNS]  Listening.")
 	return nil
@@ -1573,3 +1576,34 @@ func (service *HTTPRestService) getNetPluginDetails() *networkcontainers.NetPlug
 	configPath, _ := service.GetOption(acn.OptNetPluginConfigFile).(string)
 	return networkcontainers.NewNetPluginConfiguration(pluginBinPath, configPath)
 }
+
+// Retrieves the number of logic processors on a node. It will be primarily
+// used to enforce per VM delegated NIC limit by DNC.
+func (service *HTTPRestService) getNumberOfCPUCores(w http.ResponseWriter, r *http.Request) {
+	log.Printf("[Azure-CNS] getNumberOfCPUCores")
+	log.Request(service.Name, "getNumberOfCPUCores", nil)
+
+	var (
+		num        int
+		returnCode int
+		errMsg     string
+	)
+
+	switch r.Method {
+	case "GET":
+		num = runtime.NumCPU()
+	default:
+		errMsg = "[Azure-CNS] getNumberOfCPUCores API expects a GET."
+		returnCode = UnsupportedVerb
+	}
+
+	resp := cns.Response{ReturnCode: returnCode, Message: errMsg}
+	numOfCPUCoresResp := cns.NumOfCPUCoresResponse{
+		Response:      resp,
+		NumOfCPUCores: num,
+	}
+
+	err := service.Listener.Encode(w, &numOfCPUCoresResp)
+
+	log.Response(service.Name, numOfCPUCoresResp, resp.ReturnCode, ReturnCodeToString(resp.ReturnCode), err)
+}

cns/restserver/restserver_test.go

@@ -689,3 +689,29 @@ func TestGetInterfaceForNetworkContainer(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestGetNumOfCPUCores(t *testing.T) {
+	fmt.Println("Test: getNumberOfCPUCores")
+
+	var (
+		err error
+		req *http.Request
+	)
+
+	req, err = http.NewRequest(http.MethodGet, cns.NumberOfCPUCoresPath, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var w *httptest.ResponseRecorder
+	w = httptest.NewRecorder()
+	mux.ServeHTTP(w, req)
+	var numOfCoresResponse cns.NumOfCPUCoresResponse
+
+	err = decodeResponse(w, &numOfCoresResponse)
+	if err != nil || numOfCoresResponse.Response.ReturnCode != 0 {
+		t.Errorf("getNumberOfCPUCores failed with response %+v", numOfCoresResponse)
+	} else {
+		fmt.Printf("getNumberOfCPUCores Responded with %+v\n", numOfCoresResponse)
+	}
+}