Google App Engine - urlFetch address not in _netblocks.google.com

Question

For software I am developing, I need to have a list of external IP addresses that Google App Engine uses for urlFetch requests. Getting a complete list is proving difficult.

The accepted wisdom as detailed on SO is to use the output from...

dig -t txt _netblocks.google.com

...but unfortunately this list is incomplete. For example, my urlFetch requests currently emerge from unlisted addresses:

• US based App: 8.35.201.x
• EU based App: 8.35.200.x

Is there any way to get an actively updated list of external IP addresses used by urlFetch?

Answer 1

The official advice is https://developers.google.com/appengine/kb/general#static-ip. Note that relying on Static IP addresses is bad, for all the reasons listed on that page.

Answer 2

So, the answer is:

dig txt _cloud-netblocks.googleusercontent.com +short
"v=spf1 include:_cloud-netblocks1.googleusercontent.com include:_cloud-netblocks2.googleusercontent.com include:_cloud-netblocks3.googleusercontent.com ?all"