This change is to ensure that all members returned during the client's
AutoSync are started and are not learners, which are not valid
etcd members to make requests to.
This attempts to fix a special case of the problem described in #12385,
where trying to do `clientv3.Watch` with an expired token would result
in `ErrGRPCPermissionDenied`, due to the failing authorization check in
`isWatchPermitted`. Furthermore, the client can't auto recover, since
`shouldRefreshToken` rightly returns false for the permission denied
error.
In this case, we would like to have a runbook to dynamically disable
auth, without causing any disruption. Doing so would immediately expire
all existing tokens, which would then cause the behavior described
above. This means existing watchers would still work for a period of
time after disabling auth, until they have to reconnect, e.g. due to a
rolling restart of server nodes.
This commit adds a client-side fix and a server-side fix, either of
which is sufficient to get the added test case to pass. Note that it is
an e2e test case instead of an integration one, as the reconnect only
happens if the server node is stopped via SIGINT or SIGTERM.
A generic fix for the problem described in #12385 would be better, as
that shall also fix this special case. However, the fix would likely be
a lot more involved, as some untangling of authn/authz is required.
`Client.dial` can be called multiple times. For example, from regular
`NewClient` and [from the `Maintenance`
wrapper](6d451ab61d/client/v3/maintenance.go (L81-L84)).
This ends up creating two (if `Client.dial` is called twice) independent
`credentials.Bundle` instances:
- the first one is wired into `PerRPCCredentials` callback in gRPC
client.
- the second one is in `Client.authTokenBundle` and receives the latest
auth token updates.
When using username/password authentication and the server is configured
to issue JWTs, token rotation logic breaks because of the above
`credentials.Bundle` confusion.
clientv3 logs (especially tests) were poluted with unattributed to testing.T log lines:
```
{"level":"warn","ts":"2021-04-29T12:42:11.055+0200","logger":"etcd-client","caller":"v3/retry_interceptor.go:64","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc0000fafc0/#initially=[unix://localhost:m10]","attempt":0,"error":"rpc error: code = ResourceExhausted desc = etcdserver: mvcc: database space exceeded"}
```
The reasons were 2 fold:
- Interceptors were copying logger before "WithLogger" could modify it.
- We were not propagating the loggers in a few testing contexts.
