aws: fixes ELB creation with multiple subnets per AZ

pkg/cloudprovider/providers/aws/aws.go

@@ -41,6 +41,7 @@ import (
 
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/cloudprovider"
+	"k8s.io/kubernetes/pkg/util/sets"
 
 	"github.com/golang/glog"
 )
@@ -1571,6 +1572,40 @@ func (s *AWSCloud) createTags(request *ec2.CreateTagsInput) (*ec2.CreateTagsOutp
 	}
 }
 
+func (s *AWSCloud) listSubnetIDsinVPC(vpc *ec2.Vpc) ([]string, error) {
+
+	subnetIds := []string{}
+
+	request := &ec2.DescribeSubnetsInput{}
+	filters := []*ec2.Filter{}
+	filters = append(filters, newEc2Filter("vpc-id", orEmpty(vpc.VpcId)))
+	// Note, this will only return subnets tagged with the cluster identifier for this Kubernetes cluster.
+	// In the case where an AZ has public & private subnets per AWS best practices, the deployment should ensure
+	// only the public subnet (where the ELB will go) is so tagged.
+	filters = s.addFilters(filters)
+	request.Filters = filters
+
+	subnets, err := s.ec2.DescribeSubnets(request)
+	if err != nil {
+		glog.Error("error describing subnets: ", err)
+		return nil, err
+	}
+
+	availabilityZones := sets.NewString()
+	for _, subnet := range subnets {
+		az := orEmpty(subnet.AvailabilityZone)
+		id := orEmpty(subnet.SubnetId)
+		if availabilityZones.Has(az) {
+			glog.Warning("Found multiple subnets per AZ '", az, "', ignoring subnet '", id, "'")
+			continue
+		}
+		subnetIds = append(subnetIds, id)
+		availabilityZones.Insert(az)
+	}
+
+	return subnetIds, nil
+}
+
 // EnsureTCPLoadBalancer implements TCPLoadBalancer.EnsureTCPLoadBalancer
 // TODO(justinsb) It is weird that these take a region.  I suspect it won't work cross-region anwyay.
 func (s *AWSCloud) EnsureTCPLoadBalancer(name, region string, publicIP net.IP, ports []*api.ServicePort, hosts []string, affinity api.ServiceAffinity) (*api.LoadBalancerStatus, error) {
@@ -1604,32 +1639,10 @@ func (s *AWSCloud) EnsureTCPLoadBalancer(name, region string, publicIP net.IP, p
 	}
 
 	// Construct list of configured subnets
-	subnetIDs := []string{}
-	{
-		request := &ec2.DescribeSubnetsInput{}
-		filters := []*ec2.Filter{}
-		filters = append(filters, newEc2Filter("vpc-id", orEmpty(vpc.VpcId)))
-		// Note, this will only return subnets tagged with the cluster identifier for this Kubernetes cluster.
-		// In the case where an AZ has public & private subnets per AWS best practices, the deployment should ensure
-		// only the public subnet (where the ELB will go) is so tagged.
-		filters = s.addFilters(filters)
-		request.Filters = filters
-
-		subnets, err := s.ec2.DescribeSubnets(request)
-		if err != nil {
-			glog.Error("Error describing subnets: ", err)
-			return nil, err
-		}
-
-		//	zones := []string{}
-		for _, subnet := range subnets {
-			subnetIDs = append(subnetIDs, orEmpty(subnet.SubnetId))
-			if !strings.HasPrefix(orEmpty(subnet.AvailabilityZone), region) {
-				glog.Error("Found AZ that did not match region", orEmpty(subnet.AvailabilityZone), " vs ", region)
-				return nil, fmt.Errorf("invalid AZ for region")
-			}
-			//		zones = append(zones, subnet.AvailabilityZone)
-		}
+	subnetIDs, err := s.listSubnetIDsinVPC(vpc)
+	if err != nil {
+		glog.Error("error listing subnets in VPC", err)
+		return nil, err
 	}
 
 	// Create a security group for the load balancer

pkg/cloudprovider/providers/aws/aws_test.go

@@ -247,7 +247,9 @@ func TestNewAWSCloud(t *testing.T) {
 }
 
 type FakeEC2 struct {
-	aws *FakeAWSServices
+	aws                  *FakeAWSServices
+	Subnets              []*ec2.Subnet
+	DescribeSubnetsInput *ec2.DescribeSubnetsInput
 }
 
 func contains(haystack []*string, needle string) bool {
@@ -385,8 +387,9 @@ func (ec2 *FakeEC2) DescribeVPCs(*ec2.DescribeVpcsInput) ([]*ec2.Vpc, error) {
 	panic("Not implemented")
 }
 
-func (ec2 *FakeEC2) DescribeSubnets(*ec2.DescribeSubnetsInput) ([]*ec2.Subnet, error) {
-	panic("Not implemented")
+func (ec2 *FakeEC2) DescribeSubnets(request *ec2.DescribeSubnetsInput) ([]*ec2.Subnet, error) {
+	ec2.DescribeSubnetsInput = request
+	return ec2.Subnets, nil
 }
 
 func (ec2 *FakeEC2) CreateTags(*ec2.CreateTagsInput) (*ec2.CreateTagsOutput, error) {
@@ -697,3 +700,92 @@ func TestLoadBalancerMatchesClusterRegion(t *testing.T) {
 		t.Errorf("Expected UpdateTCPLoadBalancer region mismatch error.")
 	}
 }
+
+func constructSubnets(subnetsIn map[int]map[string]string) (subnetsOut []*ec2.Subnet) {
+	for i := range subnetsIn {
+		subnetsOut = append(
+			subnetsOut,
+			constructSubnet(
+				subnetsIn[i]["id"],
+				subnetsIn[i]["az"],
+			),
+		)
+	}
+	return
+}
+
+func constructSubnet(id string, az string) *ec2.Subnet {
+	return &ec2.Subnet{
+		SubnetId:         &id,
+		AvailabilityZone: &az,
+	}
+}
+
+func TestSubnetIDsinVPC(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 := "vpc-deadbeef"
+	vpc := &ec2.Vpc{
+		VpcId: &vpcID,
+	}
+
+	// test with 3 subnets from 3 different AZs
+	subnets := make(map[int]map[string]string)
+	subnets[0] = make(map[string]string)
+	subnets[0]["id"] = "subnet-a0000001"
+	subnets[0]["az"] = "af-south-1a"
+	subnets[1] = make(map[string]string)
+	subnets[1]["id"] = "subnet-b0000001"
+	subnets[1]["az"] = "af-south-1b"
+	subnets[2] = make(map[string]string)
+	subnets[2]["id"] = "subnet-c0000001"
+	subnets[2]["az"] = "af-south-1c"
+	awsServices.ec2.Subnets = constructSubnets(subnets)
+
+	result, err := c.listSubnetIDsinVPC(vpc)
+	if err != nil {
+		t.Errorf("Error listing subnets: %v", err)
+		return
+	}
+
+	if len(result) != 3 {
+		t.Errorf("Expected 3 subnets but got %d", len(result))
+		return
+	}
+
+	result_set := make(map[string]bool)
+	for _, v := range result {
+		result_set[v] = true
+	}
+
+	for i := range subnets {
+		if !result_set[subnets[i]["id"]] {
+			t.Errorf("Expected subnet%d '%s' in result: %v", i, subnets[i]["id"], result)
+			return
+		}
+	}
+
+	// test with 4 subnets from 3 different AZs
+	// add duplicate az subnet
+	subnets[3] = make(map[string]string)
+	subnets[3]["id"] = "subnet-c0000002"
+	subnets[3]["az"] = "af-south-1c"
+	awsServices.ec2.Subnets = constructSubnets(subnets)
+
+	result, err = c.listSubnetIDsinVPC(vpc)
+	if err != nil {
+		t.Errorf("Error listing subnets: %v", err)
+		return
+	}
+
+	if len(result) != 3 {
+		t.Errorf("Expected 3 subnets but got %d", len(result))
+		return
+	}
+
+}