Hello -
The Cloud Build service is experiencing a network issue right now with the public API. We expect this to be resolved very shortly, and will update here.
Hello -
Cloud Build is available once again as of 3:30PM Central US time. A network change to some subnets containing Cloud Build’s API servers unexpectedly ended up dropping the rules allowing normal outbound traffic - this was spotted and reverted quickly, but then the relevant processes on hosts within those subnets all needed to be restarted. Everything should be back in normal operations now.