Throw CNI error - On CNI DEL call, if communication with CNS cannot be established.

cni/network/network.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/Azure/azure-container-networking/aitelemetry"
 	"github.com/Azure/azure-container-networking/cni"
+	"github.com/Azure/azure-container-networking/cni/utils"
 	"github.com/Azure/azure-container-networking/cns"
 	"github.com/Azure/azure-container-networking/cns/cnsclient"
 	"github.com/Azure/azure-container-networking/common"
@@ -710,6 +711,7 @@ func (plugin *netPlugin) Get(args *cniSkel.CmdArgs) error {
 
 	// Initialize values from network config.
 	if networkId, err = getNetworkName(k8sPodName, k8sNamespace, args.IfName, nwCfg); err != nil {
+		// TODO: Ideally we should return from here only.
 		log.Printf("[cni-net] Failed to extract network name from network config. error: %v", err)
 	}
 
@@ -796,8 +798,16 @@ func (plugin *netPlugin) Delete(args *cniSkel.CmdArgs) error {
 	}
 
 	// Initialize values from network config.
-	if networkId, err = getNetworkName(k8sPodName, k8sNamespace, args.IfName, nwCfg); err != nil {
+	networkId, err = getNetworkName(k8sPodName, k8sNamespace, args.IfName, nwCfg)
+
+	// If error is not found error, then we ignore it, to comply with CNI SPEC.
+	if err != nil {
 		log.Printf("[cni-net] Failed to extract network name from network config. error: %v", err)
+
+		if !utils.IsNotFoundError(err) {
+			err = plugin.Errorf("Failed to extract network name from network config. error: %v", err)
+			return err
+		}
 	}
 
 	endpointId := GetEndpointID(args)

cni/network/network_windows.go

@@ -153,19 +153,30 @@ func updateSubnetPrefix(cnsNwConfig *cns.GetNetworkContainerResponse, subnetPref
 	return nil
 }
 
-func getNetworkName(podName, podNs, ifName string, nwCfg *cni.NetworkConfig) (networkName string, err error) {
+func getNetworkName(podName, podNs, ifName string, nwCfg *cni.NetworkConfig) (string, error) {
+	var (
+		networkName      string
+		err              error
+		cnsNetworkConfig *cns.GetNetworkContainerResponse
+	)
+
 	networkName = nwCfg.Name
 	err = nil
+
 	if nwCfg.MultiTenancy {
 		determineWinVer()
 		if len(strings.TrimSpace(podName)) == 0 || len(strings.TrimSpace(podNs)) == 0 {
 			err = fmt.Errorf("POD info cannot be empty. PodName: %s, PodNamespace: %s", podName, podNs)
-			return
+			return networkName, err
 		}
 
-		_, cnsNetworkConfig, _, err := getContainerNetworkConfiguration(nwCfg, podName, podNs, ifName)
+		_, cnsNetworkConfig, _, err = getContainerNetworkConfiguration(nwCfg, podName, podNs, ifName)
 		if err != nil {
-			log.Printf("GetContainerNetworkConfiguration failed for podname %v namespace %v with error %v", podName, podNs, err)
+			log.Printf(
+				"GetContainerNetworkConfiguration failed for podname %v namespace %v with error %v",
+				podName,
+				podNs,
+				err)
 		} else {
 			var subnet net.IPNet
 			if err = updateSubnetPrefix(cnsNetworkConfig, &subnet); err == nil {
@@ -177,7 +188,7 @@ func getNetworkName(podName, podNs, ifName string, nwCfg *cni.NetworkConfig) (ne
 		}
 	}
 
-	return
+	return networkName, err
 }
 
 func setupInfraVnetRoutingForMultitenancy(

cni/utils/errutils.go

@@ -0,0 +1,15 @@
+package utils
+
+import (
+	"github.com/Azure/azure-container-networking/cns/cnsclient"
+	"github.com/Azure/azure-container-networking/cns/restserver"
+)
+
+// TODO : Move to common directory like common, after fixing circular dependencies
+func IsNotFoundError(err error) bool {
+	switch e := err.(type) {
+	case *cnsclient.CNSClientError:
+		return (e.Code == restserver.UnknownContainerID)
+	}
+	return false
+}

cns/cnsclient/cnsclient.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 
 	"github.com/Azure/azure-container-networking/cns"
+	"github.com/Azure/azure-container-networking/cns/restserver"
 	"github.com/Azure/azure-container-networking/log"
 )
 
@@ -44,15 +45,20 @@ func GetCnsClient() (*CNSClient, error) {
 	var err error
 
 	if cnsClient == nil {
-		err = fmt.Errorf("[Azure CNSClient] CNS Client not initialized")
+		err = &CNSClientError{
+			restserver.UnexpectedError,
+			fmt.Errorf("[Azure CNSClient] CNS Client not initialized")}
 	}
 
 	return cnsClient, err
 }
 
 // GetNetworkConfiguration Request to get network config.
-func (cnsClient *CNSClient) GetNetworkConfiguration(orchestratorContext []byte) (*cns.GetNetworkContainerResponse, error) {
-	var body bytes.Buffer
+func (cnsClient *CNSClient) GetNetworkConfiguration(orchestratorContext []byte) (
+	*cns.GetNetworkContainerResponse, error) {
+	var (
+		body bytes.Buffer
+	)
 
 	httpc := &http.Client{}
 	url := cnsClient.connectionURL + cns.GetNetworkContainerByOrchestratorContext
@@ -65,34 +71,37 @@ func (cnsClient *CNSClient) GetNetworkConfiguration(orchestratorContext []byte)
 	err := json.NewEncoder(&body).Encode(payload)
 	if err != nil {
 		log.Errorf("encoding json failed with %v", err)
-		return nil, err
+		return nil, &CNSClientError{restserver.UnexpectedError, err}
 	}
 
 	res, err := httpc.Post(url, contentTypeJSON, &body)
 	if err != nil {
 		log.Errorf("[Azure CNSClient] HTTP Post returned error %v", err.Error())
-		return nil, err
+		return nil, &CNSClientError{restserver.UnexpectedError, err}
 	}
 
 	defer res.Body.Close()
 
 	if res.StatusCode != http.StatusOK {
 		errMsg := fmt.Sprintf("[Azure CNSClient] GetNetworkConfiguration invalid http status code: %v", res.StatusCode)
 		log.Errorf(errMsg)
-		return nil, fmt.Errorf(errMsg)
+		return nil, &CNSClientError{restserver.UnexpectedError, fmt.Errorf(errMsg)}
 	}
 
 	var resp cns.GetNetworkContainerResponse
 
 	err = json.NewDecoder(res.Body).Decode(&resp)
 	if err != nil {
 		log.Errorf("[Azure CNSClient] Error received while parsing GetNetworkConfiguration response resp:%v err:%v", res.Body, err.Error())
-		return nil, err
+		return nil, &CNSClientError{restserver.UnexpectedError, err}
 	}
 
 	if resp.Response.ReturnCode != 0 {
-		log.Errorf("[Azure CNSClient] GetNetworkConfiguration received error response :%v", resp.Response.Message)
-		return nil, fmt.Errorf(resp.Response.Message)
+		log.Errorf(
+			"[Azure CNSClient] GetNetworkConfiguration received error response :%v , Code : %d",
+			resp.Response.Message,
+			resp.Response.ReturnCode)
+		return nil, &CNSClientError{resp.Response.ReturnCode, fmt.Errorf(resp.Response.Message)}
 	}
 
 	return &resp, nil

cns/cnsclient/error.go

@@ -0,0 +1,15 @@
+package cnsclient
+
+import (
+	"fmt"
+)
+
+// CNSClientError records an error and relevant code
+type CNSClientError struct {
+	Code int
+	Err  error
+}
+
+func (e *CNSClientError) Error() string {
+	return fmt.Sprintf("[Azure CNSClient] Code: %d , Error: %v", e.Code, e.Err)
+}