def generate_instance_identity_document(instance):
    """
    http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html

    A JSON file that describes an instance. Usually retrieved by URL:
    http://169.254.169.254/latest/dynamic/instance-identity/document
    Here we just fill a dictionary that represents the document

    Typically, this document is used by the amazon-ecs-agent when registering a
    new ContainerInstance
    """
    document = {'devPayProductCodes': None, 'availabilityZone': instance.
        placement['AvailabilityZone'], 'privateIp': instance.
        private_ip_address, 'version': '2010-8-31', 'region': instance.
        placement['AvailabilityZone'][:-1], 'instanceId': instance.id,
        'billingProducts': None, 'instanceType': instance.instance_type,
        'accountId': '012345678910', 'pendingTime': '2015-11-19T16:32:11Z',
        'imageId': instance.image_id, 'kernelId': instance.kernel_id,
        'ramdiskId': instance.ramdisk_id, 'architecture': instance.architecture
        }
    return document
