use NODE_NAME env variable to get the node object when running as daemon set

If NODE_NAME env is not set, fall back to hostname.

Partial fix towards #23 we still have issue where kube-router is run as agent
and kubelet is started with --hostname-overide flag

Author: Murali Reddy

app/controllers/network_policy_controller.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"net"
-	"os"
 	"os/exec"
 	"strconv"
 	"strings"
@@ -20,7 +19,6 @@ import (
 	"github.com/coreos/go-iptables/iptables"
 	"github.com/golang/glog"
 	"github.com/janeczku/go-ipset/ipset"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	apiv1 "k8s.io/client-go/pkg/api/v1"
 )
@@ -772,22 +770,12 @@ func NewNetworkPolicyController(clientset *kubernetes.Clientset, config *options
 
 	npc.syncPeriod = config.IPTablesSyncPeriod
 
-	nodeHostName, err := os.Hostname()
+	node, err := utils.GetNodeObject(clientset)
 	if err != nil {
 		panic(err.Error())
 	}
-	nodeFqdnHostName := utils.GetFqdn()
 
-	node, err := clientset.Core().Nodes().Get(nodeHostName, metav1.GetOptions{})
-	if err != nil {
-		node, err = clientset.Core().Nodes().Get(nodeFqdnHostName, metav1.GetOptions{})
-		if err != nil {
-			panic(err.Error())
-		}
-		npc.nodeHostName = nodeFqdnHostName
-	} else {
-		npc.nodeHostName = nodeHostName
-	}
+	npc.nodeHostName = node.Name
 
 	nodeIP, err := getNodeIP(node)
 	if err != nil {

app/controllers/network_routes_controller.go

@@ -3,7 +3,6 @@ package controllers
 import (
 	"fmt"
 	"net"
-	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -358,22 +357,13 @@ func NewNetworkRoutingController(clientset *kubernetes.Clientset, kubeRouterConf
 		nrc.peerAsnNumber = uint32(asn)
 	}
 
-	nodeHostName, err := os.Hostname()
+
+	node, err := utils.GetNodeObject(clientset)
 	if err != nil {
 		panic(err.Error())
 	}
-	nodeFqdnHostName := utils.GetFqdn()
 
-	node, err := clientset.Core().Nodes().Get(nodeHostName, metav1.GetOptions{})
-	if err != nil {
-		node, err = clientset.Core().Nodes().Get(nodeFqdnHostName, metav1.GetOptions{})
-		if err != nil {
-			panic(err.Error())
-		}
-		nrc.nodeHostName = nodeFqdnHostName
-	} else {
-		nrc.nodeHostName = nodeHostName
-	}
+	nrc.nodeHostName = node.Name
 
 	nodeIP, err := getNodeIP(node)
 	if err != nil {

app/controllers/network_services_controller.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net"
-	"os"
 	"reflect"
 	"strconv"
 	"strings"
@@ -20,7 +19,6 @@ import (
 	"github.com/golang/glog"
 	"github.com/mqliang/libipvs"
 	"github.com/vishvananda/netlink"
-	"k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 )
 
@@ -543,22 +541,12 @@ func NewNetworkServicesController(clientset *kubernetes.Clientset, config *optio
 		nsc.podCidr = cidr
 	}
 
-	nodeHostName, err := os.Hostname()
+	node, err := utils.GetNodeObject(clientset)
 	if err != nil {
 		panic(err.Error())
 	}
-	nodeFqdnHostName := utils.GetFqdn()
 
-	node, err := clientset.Core().Nodes().Get(nodeHostName, v1.GetOptions{})
-	if err != nil {
-		node, err = clientset.Core().Nodes().Get(nodeFqdnHostName, v1.GetOptions{})
-		if err != nil {
-			panic(err.Error())
-		}
-		nsc.nodeHostName = nodeFqdnHostName
-	} else {
-		nsc.nodeHostName = nodeHostName
-	}
+	nsc.nodeHostName = node.Name
 	nodeIP, err := getNodeIP(node)
 	if err != nil {
 		panic(err.Error())

utils/node.go

@@ -0,0 +1,38 @@
+package utils
+
+import (
+	"os"
+	"fmt"
+
+	"k8s.io/client-go/kubernetes"
+	apiv1 "k8s.io/client-go/pkg/api/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func GetNodeObject(clientset *kubernetes.Clientset) (*apiv1.Node, error) {
+
+	// assuming kube-router is running as pod, first check env NODE_NAME
+	nodeName := os.Getenv("NODE_NAME")
+	if nodeName != "" {
+		node, err := clientset.Core().Nodes().Get(nodeName, metav1.GetOptions{})
+		if err == nil {
+			return node, nil
+		}
+	}
+
+	// if env NODE_NAME is not set then check if node is register with hostname
+	hostName, _ := os.Hostname()
+	node, err := clientset.Core().Nodes().Get(hostName, metav1.GetOptions{})
+	if err == nil {
+		return node, nil
+	}
+
+	// if env NODE_NAME is not set then check if node is registerd by FQDN
+	fqdnHostName := GetFqdn()
+	node, err = clientset.Core().Nodes().Get(fqdnHostName, metav1.GetOptions{})
+	if err == nil {
+		return node, nil
+	}
+
+	return nil, fmt.Errorf("Failed to identify the node by NODE_NAME, hostname or FQDN name of the host")
+}

utils/pod_cidr.go

@@ -5,11 +5,9 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net"
-	"os"
 
 	"github.com/containernetworking/cni/libcni"
 	"github.com/containernetworking/cni/plugins/ipam/host-local/backend/allocator"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 )
 
@@ -48,17 +46,9 @@ func InsertPodCidrInCniSpec(cniConfFilePath string, cidr string) error {
 }
 
 func GetPodCidrFromNodeSpec(clientset *kubernetes.Clientset) (string, error) {
-	nodeHostName, err := os.Hostname()
+	node, err := GetNodeObject(clientset)
 	if err != nil {
-		panic(err.Error())
-	}
-	nodeFqdnHostName := GetFqdn()
-	node, err := clientset.Core().Nodes().Get(nodeHostName, metav1.GetOptions{})
-	if err != nil {
-		node, err = clientset.Core().Nodes().Get(nodeFqdnHostName, metav1.GetOptions{})
-		if err != nil {
-			panic(err.Error())
-		}
+		return "", fmt.Errorf("Failed to get pod CIDR allocated for the node due to: " + err.Error())
 	}
 	return node.Spec.PodCIDR, nil
 }