When etcdserver receives a LeaseRenew request, it may be still in
progress of processing the LeaseGrantRequest on exact the same
leaseID. Accordingly it may return a TTL=0 to client due to the
leaseID not found error. So the leader should wait for the appliedID
to be available before processing client requests.
While it appears that etcd is not vulnerable to CVE-2021-3121,
it is a good idea to update to the new generator so that new
vulnerable code isn't generated in any future APIs. Also, this
lays the issue to rest of whether there is any issue with
etcd and CVE-2021-3121.
Before this patch, a client which cancels the context for a watch results in the
server generating a `rpctypes.ErrGRPCNoLeader` error that leads the recording of
a gRPC `Unavailable` metric in association with the client watch cancellation.
The metric looks like this:
grpc_server_handled_total{grpc_code="Unavailable",grpc_method="Watch",grpc_service="etcdserverpb.Watch",grpc_type="bidi_stream"}
So, the watch server has misidentified the error as a server error and then
propagates the mistake to metrics, leading to a false indicator that the leader
has been lost. This false signal then leads to false alerting.
The commit 9c103dd0de introduced an interceptor which wraps
watch streams requiring a leader, causing those streams to be actively canceled
when leader loss is detected.
However, the error handling code assumes all stream context cancellations are
from the interceptor. This assumption is broken when the context was canceled
because of a client stream cancelation.
The core challenge is lack of information conveyed via `context.Context` which
is shared by both the send and receive sides of the stream handling and is
subject to cancellation by all paths (including the gRPC library itself). If any
piece of the system cancels the shared context, there's no way for a context
consumer to understand who cancelled the context or why.
To solve the ambiguity of the stream interceptor code specifically, this patch
introduces a custom context struct which the interceptor uses to expose a custom
error through the context when the interceptor decides to actively cancel a
stream. Now the consuming side can more safely assume a generic context
cancellation can be propagated as a cancellation, and the server generated
leader error is preserved and propagated normally without any special inference.
When a client cancels the stream, there remains a race in the error handling
code between the send and receive goroutines whereby the underlying gRPC error
is lost in the case where the send path returns and is handled first, but this
issue can be taken separately as no matter which paths wins, we can detect a
generic cancellation.
This is a replacement of https://github.com/etcd-io/etcd/pull/11375.
Fixes#10289, #9725, #9576, #9166
This brings consistency between proto-generation code and actual versions of libraries being used in runtime:
github.com/gogo/protobuf v1.2.1,v1.0.0 -> v1.3.1
github.com/golang/protobuf v1.3.2 -> v1.3.5
github.com/grpc-ecosystem/grpc-gateway v1.9.5,v1.4.1,v1.15.2 -> v1.14.6
google.golang.org/grpc v1.26.0 -> v1.29.1
Moved as far as possible, without bumping on grpc 1.30.0 "naming" decomissioning.
Please also notice that gogo/protobuf is likely to reach EOL: https://github.com/gogo/protobuf/issues/691
The module is supposed to contain minimal set of files that establish
public etcd server API. In particular client libraries for etcd built in
different languages might want to depend on this file.
