add proper message when reading pod CIDR from cni conf file (#450)

Author: murali-reddy

pkg/controllers/routing/network_routes_controller.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"os"
 	"os/exec"
+	"reflect"
 	"strconv"
 	"strings"
 	"sync"
@@ -101,18 +102,21 @@ func (nrc *NetworkRoutingController) Run(healthChan chan<- *healthcheck.Controll
 	if err != nil {
 		glog.Errorf("Failed to get pod CIDR from CNI conf file: %s", err.Error())
 	}
+	if reflect.DeepEqual(cidr, net.IPNet{}) {
+		glog.Infof("`subnet` in CNI conf file is empty so populating `subnet` in CNI conf file with pod CIDR assigned to the node obtained from node spec.")
+	}
 	cidrlen, _ := cidr.Mask.Size()
 	oldCidr := cidr.IP.String() + "/" + strconv.Itoa(cidrlen)
 
 	currentCidr, err := utils.GetPodCidrFromNodeSpec(nrc.clientset, nrc.hostnameOverride)
 	if err != nil {
-		glog.Errorf("Failed to get pod CIDR from node spec: %s", err.Error())
+		glog.Fatalf("Failed to get pod CIDR from node spec. kube-router relies on kube-controller-manager to allocate pod CIDR for the node. Error: %v", err.Error())
 	}
 
 	if len(cidr.IP) == 0 || strings.Compare(oldCidr, currentCidr) != 0 {
 		err = utils.InsertPodCidrInCniSpec(nrc.cniConfFile, currentCidr)
 		if err != nil {
-			glog.Errorf("Failed to insert pod CIDR into CNI conf file: %s", err.Error())
+			glog.Fatalf("Failed to insert `subnet`(pod CIDR) into CNI conf file: %s", err.Error())
 		}
 	}
 

pkg/utils/pod_cidr.go

@@ -2,11 +2,9 @@ package utils
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"net"
-	"reflect"
 	"strings"
 
 	"github.com/containernetworking/cni/libcni"
@@ -50,9 +48,6 @@ func GetPodCidrFromCniSpec(cniConfFilePath string) (net.IPNet, error) {
 		}
 	}
 	podCidr = net.IPNet(ipamConfig.Subnet)
-	if reflect.DeepEqual(podCidr, net.IPNet{}) {
-		return net.IPNet{}, errors.New("subnet missing from CNI IPAM")
-	}
 	return podCidr, nil
 }
 

pkg/utils/pod_cidr_test.go

@@ -36,7 +36,7 @@ func Test_GetPodCidrFromCniSpec(t *testing.T) {
 			"CNI config file missing subnet",
 			`{"bridge":"kube-bridge","ipam":{"type":"host-local"},"isDefaultGateway":true,"name":"kubernetes","type":"bridge"}`,
 			net.IPNet{},
-			errors.New("subnet missing from CNI IPAM"),
+			nil,
 			"10-kuberouter.conf",
 		},
 	}