AWS support for Zones

pkg/cloudprovider/aws/aws.go

@@ -37,16 +37,22 @@ import (
 type EC2 interface {
 	// Query EC2 for instances matching the filter
 	Instances(instIds []string, filter *ec2InstanceFilter) (resp *ec2.InstancesResp, err error)
+
+	// Query the EC2 metadata service (used to discover instance-id etc)
+	GetMetaData(key string) ([]byte, error)
 }
 
 // AWSCloud is an implementation of Interface, TCPLoadBalancer and Instances for Amazon Web Services.
 type AWSCloud struct {
-	ec2 EC2
-	cfg *AWSCloudConfig
+	ec2              EC2
+	cfg              *AWSCloudConfig
+	availabilityZone string
+	region           aws.Region
 }
 
 type AWSCloudConfig struct {
 	Global struct {
+		// TODO: Is there any use for this?  We can get it from the instance metadata service
 		Region string
 	}
 }
@@ -82,6 +88,14 @@ func (self *GoamzEC2) Instances(instanceIds []string, filter *ec2InstanceFilter)
 	return self.ec2.Instances(instanceIds, goamzFilter)
 }
 
+func (self *GoamzEC2) GetMetaData(key string) ([]byte, error) {
+	v, err := aws.GetMetaData(key)
+	if err != nil {
+		return nil, fmt.Errorf("Error querying AWS metadata for key %s: %v", key, err)
+	}
+	return v, nil
+}
+
 type AuthFunc func() (auth aws.Auth, err error)
 
 func init() {
@@ -125,18 +139,36 @@ func newAWSCloud(config io.Reader, authFunc AuthFunc) (*AWSCloud, error) {
 		return nil, err
 	}
 
+	// TODO: We can get the region very easily from the instance-metadata service
 	region, ok := aws.Regions[cfg.Global.Region]
 	if !ok {
 		return nil, fmt.Errorf("not a valid AWS region: %s", cfg.Global.Region)
 	}
 
-	ec2 := ec2.New(auth, region)
 	return &AWSCloud{
-		ec2: &GoamzEC2{ec2: ec2},
-		cfg: cfg,
+		ec2:    &GoamzEC2{ec2: ec2.New(auth, region)},
+		cfg:    cfg,
+		region: region,
 	}, nil
 }
 
+func (self *AWSCloud) getAvailabilityZone() (string, error) {
+	// TODO: Do we need sync.Mutex here?
+	availabilityZone := self.availabilityZone
+	if self.availabilityZone == "" {
+		availabilityZoneBytes, err := self.ec2.GetMetaData("placement/availability-zone")
+		if err != nil {
+			return "", err
+		}
+		if availabilityZoneBytes == nil || len(availabilityZoneBytes) == 0 {
+			return "", fmt.Errorf("Unable to determine availability-zone from instance metadata")
+		}
+		availabilityZone = string(availabilityZoneBytes)
+		self.availabilityZone = availabilityZone
+	}
+	return availabilityZone, nil
+}
+
 func (aws *AWSCloud) Clusters() (cloudprovider.Clusters, bool) {
 	return nil, false
 }
@@ -153,7 +185,7 @@ func (aws *AWSCloud) Instances() (cloudprovider.Instances, bool) {
 
 // Zones returns an implementation of Zones for Amazon Web Services.
 func (aws *AWSCloud) Zones() (cloudprovider.Zones, bool) {
-	return nil, false
+	return aws, true
 }
 
 // IPAddress is an implementation of Instances.IPAddress.
@@ -246,3 +278,15 @@ func (aws *AWSCloud) List(filter string) ([]string, error) {
 func (v *AWSCloud) GetNodeResources(name string) (*api.NodeResources, error) {
 	return nil, nil
 }
+
+// GetZone implements Zones.GetZone
+func (self *AWSCloud) GetZone() (cloudprovider.Zone, error) {
+	availabilityZone, err := self.getAvailabilityZone()
+	if err != nil {
+		return cloudprovider.Zone{}, err
+	}
+	return cloudprovider.Zone{
+		FailureDomain: availabilityZone,
+		Region:        self.region.Name,
+	}, nil
+}

pkg/cloudprovider/aws/aws_test.go

@@ -76,28 +76,47 @@ func TestNewAWSCloud(t *testing.T) {
 }
 
 type FakeEC2 struct {
-	instances func(instanceIds []string, filter *ec2InstanceFilter) (resp *ec2.InstancesResp, err error)
+	instances        []ec2.Instance
+	availabilityZone string
 }
 
-func (ec2 *FakeEC2) Instances(instanceIds []string, filter *ec2InstanceFilter) (resp *ec2.InstancesResp, err error) {
-	return ec2.instances(instanceIds, filter)
+func (self *FakeEC2) Instances(instanceIds []string, filter *ec2InstanceFilter) (resp *ec2.InstancesResp, err error) {
+	matches := []ec2.Instance{}
+	for _, instance := range self.instances {
+		if filter == nil || filter.Matches(instance) {
+			matches = append(matches, instance)
+		}
+	}
+	return &ec2.InstancesResp{"",
+		[]ec2.Reservation{
+			{"", "", "", nil, matches}}}, nil
+}
+
+func (self *FakeEC2) GetMetaData(key string) ([]byte, error) {
+	if key == "placement/availability-zone" {
+		return []byte(self.availabilityZone), nil
+	} else {
+		return nil, nil
+	}
 }
 
 func mockInstancesResp(instances []ec2.Instance) (aws *AWSCloud) {
+	availabilityZone := "us-west-2d"
+	return &AWSCloud{
+		ec2: &FakeEC2{
+			instances:        instances,
+			availabilityZone: availabilityZone,
+		},
+	}
+}
+
+func mockAvailabilityZone(region string, availabilityZone string) *AWSCloud {
 	return &AWSCloud{
-		&FakeEC2{
-			func(instanceIds []string, filter *ec2InstanceFilter) (resp *ec2.InstancesResp, err error) {
-				matches := []ec2.Instance{}
-				for _, instance := range instances {
-					if filter == nil || filter.Matches(instance) {
-						matches = append(matches, instance)
-					}
-				}
-				return &ec2.InstancesResp{"",
-					[]ec2.Reservation{
-						{"", "", "", nil, matches}}}, nil
-			}},
-		nil}
+		ec2: &FakeEC2{
+			availabilityZone: availabilityZone,
+		},
+		region: aws.Regions[region],
+	}
 }
 
 func TestList(t *testing.T) {
@@ -163,3 +182,21 @@ func TestIPAddress(t *testing.T) {
 		t.Errorf("Expected %v, got %v", e, a)
 	}
 }
+
+func TestGetRegion(t *testing.T) {
+	aws := mockAvailabilityZone("us-west-2", "us-west-2e")
+	zones, ok := aws.Zones()
+	if !ok {
+		t.Fatalf("Unexpected missing zones impl")
+	}
+	zone, err := zones.GetZone()
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	if zone.Region != "us-west-2" {
+		t.Errorf("Unexpected region: %s", zone.Region)
+	}
+	if zone.FailureDomain != "us-west-2e" {
+		t.Errorf("Unexpected FailureDomain: %s", zone.FailureDomain)
+	}
+}