Tuesday, March 18, 2014
Google uses a wide range of IP addresses for its different services, and the addresses may change
without notification.
Google App Engine
is a Platform as a Service offering which hosts a wide variety of 3rd party applications. This
post announces changes in the IP address range and headers used by the Google App Engine
URLFetch (outbound HTTP) and outbound sockets APIs.
While we recommend that App Engine IP ranges not be used to filter inbound requests, we are aware that some services have created filters that rely on specific addresses. Google App Engine will be changing its IP range beginning this month. Please see these instructions to determine App Engine's IP range.
Additionally, the HTTP
User-Agent header string
that historically allowed identification of individual App Engine applications should no longer
be relied on to identify the application. With the introduction of outbound
sockets for App Engine,
applications may now make HTTP requests without using the URLFetch API, and those
requests may set a User-Agent of their own choosing.