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