Add Environ NetworkInterfaces for EC2

provider/ec2/environ.go

@@ -777,10 +777,54 @@ func (e *environ) ReleaseAddress(instId instance.Id, _ network.Id, addr network.
 	return nil
 }
 
-// NetworkInterfaces implements Environ.NetworkInterfaces, but it's
-// not implemented on this provider yet.
-func (*environ) NetworkInterfaces(_ instance.Id) ([]network.InterfaceInfo, error) {
-	return nil, errors.NotImplementedf("NetworkInterfaces")
+// NetworkInterfaces implements Environ.NetworkInterfaces.
+func (e *environ) NetworkInterfaces(instId instance.Id) ([]network.InterfaceInfo, error) {
+	ec2Client := e.ec2()
+	var err error
+	var networkInterfacesResp *ec2.NetworkInterfacesResp
+	for a := shortAttempt.Start(); a.Next(); {
+		filter := ec2.NewFilter()
+		filter.Add("attachment.instance-id", string(instId))
+		networkInterfacesResp, err = ec2Client.NetworkInterfaces(nil, filter)
+		if err == nil {
+			break
+		}
+	}
+	if err != nil {
+		// either the instance doesn't exist or we couldn't get through to
+		// the ec2 api
+		return nil, errors.Annotatef(err, "cannot get instance %v network interfaces", instId)
+	}
+	ec2Interfaces := networkInterfacesResp.Interfaces
+	result := make([]network.InterfaceInfo, len(ec2Interfaces))
+	for i, iface := range ec2Interfaces {
+		resp, err := ec2Client.Subnets([]string{iface.SubnetId}, nil)
+		if err != nil {
+			return nil, errors.Annotatef(err, "failed to retrieve subnet %v info", iface.SubnetId)
+		}
+		if len(resp.Subnets) != 1 {
+			return nil, errors.Errorf("expected 1 subnet, got %d", len(resp.Subnets))
+		}
+		subnet := resp.Subnets[0]
+		cidr := subnet.CIDRBlock
+
+		result[i] = network.InterfaceInfo{
+			DeviceIndex:      iface.Attachment.DeviceIndex,
+			MACAddress:       iface.MACAddress,
+			CIDR:             cidr,
+			NetworkName:      "", // Not needed for now.
+			ProviderId:       network.Id(iface.Id),
+			ProviderSubnetId: network.Id(iface.SubnetId),
+			VLANTag:          0, // Not supported on EC2.
+			// Not supported on EC2, so fake it.
+			InterfaceName: fmt.Sprintf("eth%d", iface.Attachment.DeviceIndex),
+			Disabled:      false,
+			NoAutoStart:   false,
+			ConfigType:    network.ConfigUnknown,
+			Address:       network.NewAddress(iface.PrivateIPAddress, network.ScopeCloudLocal),
+		}
+	}
+	return result, nil
 }
 
 // Subnets returns basic information about the specified subnets known

provider/ec2/local_test.go

@@ -799,6 +799,26 @@ func (t *localServerSuite) TestReleaseAddress(c *gc.C) {
 	c.Assert(err, gc.ErrorMatches, msg)
 }
 
+func (t *localServerSuite) TestNetworkInterfaces(c *gc.C) {
+	env, instId := t.setUpInstanceWithDefaultVpc(c)
+	interfaces, err := env.NetworkInterfaces(instId)
+	c.Assert(err, jc.ErrorIsNil)
+	expectedInterfaces := []network.InterfaceInfo{{
+		DeviceIndex:      0,
+		MACAddress:       "20:01:60:cb:27:37",
+		CIDR:             "10.10.0.0/20",
+		ProviderId:       "eni-0",
+		ProviderSubnetId: "subnet-0",
+		VLANTag:          0,
+		InterfaceName:    "eth0",
+		Disabled:         false,
+		NoAutoStart:      false,
+		ConfigType:       "",
+		Address:          network.NewAddress("10.10.0.5", network.ScopeCloudLocal),
+	}}
+	c.Assert(interfaces, jc.DeepEquals, expectedInterfaces)
+}
+
 func (t *localServerSuite) TestSubnets(c *gc.C) {
 	env, _ := t.setUpInstanceWithDefaultVpc(c)
 	subnets, err := env.Subnets("", []network.Id{"subnet-0"})