providers/aws: expose network interface id (#6751)

Expose the network interface ID that is created with a new instance.

This can be useful when associating an existing elastic IP to the
default interface on an instance that has multiple network interfaces.

builtin/providers/aws/resource_aws_instance.go

@@ -128,6 +128,11 @@ func resourceAwsInstance() *schema.Resource {
 				Computed: true,
 			},
 
+			"network_interface_id": &schema.Schema{
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
 			"public_ip": &schema.Schema{
 				Type:     schema.TypeString,
 				Computed: true,
@@ -488,10 +493,12 @@ func resourceAwsInstanceRead(d *schema.ResourceData, meta interface{}) error {
 		for _, ni := range instance.NetworkInterfaces {
 			if *ni.Attachment.DeviceIndex == 0 {
 				d.Set("subnet_id", ni.SubnetId)
+				d.Set("network_interface_id", ni.NetworkInterfaceId)
 			}
 		}
 	} else {
 		d.Set("subnet_id", instance.SubnetId)
+		d.Set("network_interface_id", "")
 	}
 	d.Set("ebs_optimized", instance.EbsOptimized)
 	if instance.SubnetId != nil && *instance.SubnetId != "" {

website/source/docs/providers/aws/r/instance.html.markdown

@@ -152,6 +152,7 @@ The following attributes are exported:
 * `public_dns` - The public DNS name assigned to the instance. For EC2-VPC, this 
   is only available if you've enabled DNS hostnames for your VPC
 * `public_ip` - The public IP address assigned to the instance, if applicable. **NOTE**: If you are using an [`aws_eip`](/docs/providers/aws/r/eip.html) with your instance, you should refer to the EIP's address directly and not use `public_ip`, as this field will change after the EIP is attached.
+* `network_interface_id` - The ID of the network interface that was created with the instance.
 * `private_dns` - The private DNS name assigned to the instance. Can only be 
   used inside the Amazon EC2, and only available if you've enabled DNS hostnames 
   for your VPC