correct way to check internet connection goes away

[ukai]

When internet connection goes away in the long running process, grpc returns

code = Unavailable desc = last connection error: connection error: desc = "transport: Error while dialing: dial tcp: lookup remotebuildexecution.googleapis.com: no such host"

(using google.golang.org/api/transport/grpc's DialPool).

How should we heck this error type?
I think we want to retry for Unavailable, but we'd like to report this error to the user without retry.

[arjan-bal]

@ukai do you know how DialPool handles failures? Does it transparently retry using a new ClientConn/Channel from the pool when one ClientConn fails? If yes, then you would always see a DNS resolution failure when sending the first request on a new ClientConn.