Cross-domain Policy File

A cross-domain policy file allows web pages hosted elsewhere to use client side technologies such as Flash, Java and Silverlight to interact with the Swift API.

See for a description of the purpose and structure of the cross-domain policy file. The cross-domain policy file is installed in the root of a web server (i.e., the path is /crossdomain.xml).

The crossdomain middleware responds to a path of /crossdomain.xml with an XML document such as:

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "" >
    <allow-access-from domain="*" secure="false" />

You should use a policy appropriate to your site. The examples and the default policy are provided to indicate how to syntactically construct a cross domain policy file – they are not recommendations.


To enable this middleware, add it to the pipeline in your proxy-server.conf file. It should be added before any authentication (e.g., tempauth or keystone) middleware. In this example ellipsis (…) indicate other middleware you may have chosen to use:

pipeline =  ... crossdomain ... authtoken ... proxy-server

And add a filter section, such as:

use = egg:swift#crossdomain
cross_domain_policy = <allow-access-from domain="*" />
    <allow-access-from domain="" secure="false" />

For continuation lines, put some whitespace before the continuation text. Ensure you put a completely blank line to terminate the cross_domain_policy value.

The cross_domain_policy name/value is optional. If omitted, the policy defaults as if you had specified:

cross_domain_policy = <allow-access-from domain="*" secure="false" />


The default policy is very permissive; this is appropriate for most public cloud deployments, but may not be appropriate for all deployments. See also: CWE-942