When you have an application deployed to Pivotal Web Services and it makes outgoing connections to other services, it is sometimes necessary to know the IP addresses from which your application's connections will originate. These may be necessary to provide a third party service provider or for access through a firewall.
PWS no longer provides a list of outgoing IP addresses that will be used by outgoing requests from applications running on PWS. If you need to provide a third-party service with a white list of IP addresses that your application will use to connect to the service, then you need to run your connection through a proxy and use the proxy's IP address for the white list.
While Pivotal does not recommend any one proxy provider, we do offer Statica though the Pivotal Marketplace which is a service that allows you to quickly spin up a proxy for use in this manner. Please see the docs for Static here. Another option would be to run your own proxy. If you choose to go this route, locating the proxy in AWS US-East-1 would put it as close to PWS as possible.
Please see the following blog post for additional details.