From 1bfba8a5902fb14d1727e6e042d521b55f37ee39 Mon Sep 17 00:00:00 2001
From: Christian Simon <simon@swine.de>
Date: Wed, 2 Sep 2015 16:28:55 +0100
Subject: [PATCH] Enhanced detection of VPC for cloudprovider AWS

* use metadata of instance rather than hardcoded VPC name
* test coverage for retrieval of network metadata
---
 pkg/cloudprovider/providers/aws/aws.go      | 35 ++++++++++++++--
 pkg/cloudprovider/providers/aws/aws_test.go | 45 +++++++++++++++++++--
 2 files changed, 73 insertions(+), 7 deletions(-)

diff --git a/pkg/cloudprovider/providers/aws/aws.go b/pkg/cloudprovider/providers/aws/aws.go
index d216232557f..6234d1ea6ef 100644
--- a/pkg/cloudprovider/providers/aws/aws.go
+++ b/pkg/cloudprovider/providers/aws/aws.go
@@ -1281,12 +1281,41 @@ func (self *AWSCloud) TCPLoadBalancerExists(name, region string) (bool, error) {
 	return false, nil
 }
 
+// Retrieves instance's vpc id from metadata
+func (self *AWSCloud) findVPCID() (string, error) {
+
+	metadata := self.awsServices.Metadata()
+	macsBytes, err := metadata.GetMetaData("network/interfaces/macs/")
+	if err != nil {
+		return "", fmt.Errorf("Could not list interfaces of the instance", err)
+	}
+
+	// loop over interfaces, first vpc id returned wins
+	for _, macPath := range strings.Split(string(macsBytes), "\n") {
+
+		if len(macPath) == 0 {
+			continue
+		}
+		url := fmt.Sprintf("network/interfaces/macs/%svpc-id", macPath)
+		vpcIDBytes, err := metadata.GetMetaData(url)
+		if err != nil {
+			continue
+		}
+		return string(vpcIDBytes), nil
+	}
+	return "", fmt.Errorf("Could not find VPC id in instance metadata")
+}
+
 // Find the kubernetes VPC
 func (self *AWSCloud) findVPC() (*ec2.VPC, error) {
 	request := &ec2.DescribeVPCsInput{}
 
-	name := "kubernetes-vpc"
-	filters := []*ec2.Filter{newEc2Filter("tag:Name", name)}
+	// find by vpcID from metadata
+	vpcID, err := self.findVPCID()
+	if err != nil {
+		return nil, err
+	}
+	filters := []*ec2.Filter{newEc2Filter("vpc-id", vpcID)}
 	request.Filters = self.addFilters(filters)
 
 	vpcs, err := self.ec2.DescribeVPCs(request)
@@ -1301,7 +1330,7 @@ func (self *AWSCloud) findVPC() (*ec2.VPC, error) {
 	if len(vpcs) == 1 {
 		return vpcs[0], nil
 	}
-	return nil, fmt.Errorf("Found multiple matching VPCs for name: %s", name)
+	return nil, fmt.Errorf("Found multiple matching VPCs for vpcID = %s", vpcID)
 }
 
 // Retrieves the specified security group from the AWS API, or returns nil if not found
diff --git a/pkg/cloudprovider/providers/aws/aws_test.go b/pkg/cloudprovider/providers/aws/aws_test.go
index 29bbd8a2e07..07171a11827 100644
--- a/pkg/cloudprovider/providers/aws/aws_test.go
+++ b/pkg/cloudprovider/providers/aws/aws_test.go
@@ -104,10 +104,12 @@ func TestReadAWSCloudConfig(t *testing.T) {
 }
 
 type FakeAWSServices struct {
-	availabilityZone string
-	instances        []*ec2.Instance
-	instanceId       string
-	privateDnsName   string
+	availabilityZone        string
+	instances               []*ec2.Instance
+	instanceId              string
+	privateDnsName          string
+	networkInterfacesMacs   []string
+	networkInterfacesVpcIDs []string
 
 	ec2      *FakeEC2
 	elb      *FakeELB
@@ -123,6 +125,9 @@ func NewFakeAWSServices() *FakeAWSServices {
 	s.asg = &FakeASG{aws: s}
 	s.metadata = &FakeMetadata{aws: s}
 
+	s.networkInterfacesMacs = []string{"aa:bb:cc:dd:ee:00", "aa:bb:cc:dd:ee:01"}
+	s.networkInterfacesVpcIDs = []string{"vpc-mac0", "vpc-mac1"}
+
 	s.instanceId = "i-self"
 	s.privateDnsName = "ip-172-20-0-100.ec2.internal"
 	var selfInstance ec2.Instance
@@ -308,12 +313,28 @@ type FakeMetadata struct {
 }
 
 func (self *FakeMetadata) GetMetaData(key string) ([]byte, error) {
+	networkInterfacesPrefix := "network/interfaces/macs/"
 	if key == "placement/availability-zone" {
 		return []byte(self.aws.availabilityZone), nil
 	} else if key == "instance-id" {
 		return []byte(self.aws.instanceId), nil
 	} else if key == "local-hostname" {
 		return []byte(self.aws.privateDnsName), nil
+	} else if strings.HasPrefix(key, networkInterfacesPrefix) {
+		if key == networkInterfacesPrefix {
+			return []byte(strings.Join(self.aws.networkInterfacesMacs, "/\n") + "/\n"), nil
+		} else {
+			keySplit := strings.Split(key, "/")
+			macParam := keySplit[3]
+			if len(keySplit) == 5 && keySplit[4] == "vpc-id" {
+				for i, macElem := range self.aws.networkInterfacesMacs {
+					if macParam == macElem {
+						return []byte(self.aws.networkInterfacesVpcIDs[i]), nil
+					}
+				}
+			}
+			return nil, nil
+		}
 	} else {
 		return nil, nil
 	}
@@ -627,3 +648,19 @@ func TestGetRegion(t *testing.T) {
 		t.Errorf("Unexpected FailureDomain: %s", zone.FailureDomain)
 	}
 }
+
+func TestFindVPCID(t *testing.T) {
+	awsServices := NewFakeAWSServices()
+	c, err := newAWSCloud(strings.NewReader("[global]"), awsServices)
+	if err != nil {
+		t.Errorf("Error building aws cloud: %v", err)
+		return
+	}
+	vpcID, err := c.findVPCID()
+	if err != nil {
+		t.Errorf("Unexpected error:", err)
+	}
+	if vpcID != "vpc-mac0" {
+		t.Errorf("Unexpected vpcID: %s", vpcID)
+	}
+}