I maintain the owon.ro domain which uses a simple App engine app. I also we use google cloud dns.
These are the dns records:
A record with IP addres
The DNS operations suggested in step 5c (documentation here) are not enough, you also need to actually add the naked domain to the GAE config (in addition to the www
one) - step 5d.
5. Continue to the next step the Add new custom domain form, selecting the custom domain you want to point to your App Engine app: a. Refresh the console domain page so it will list the domains properly. b. If you want to use a subdomain, such as www, use the second option (http://www.example.com); c. If you want to use a naked domain, use the first option to specify a naked domain (such as http://example.com). d. Click Add to create the desired mapping.