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open-consul
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peering: avoid a race between peering establishment and termination (#13389)

This commit is contained in:
R.B. Boyer 2022-06-07 16:29:09 -05:00 committed by GitHub
parent 3deaf767f2
commit bf647bc9d2
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3 changed files with 40 additions and 3 deletions
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2
agent/consul/client_test.go
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@ -510,7 +510,7 @@ func newDefaultDeps(t *testing.T, c *Config) Deps {
logger := hclog.NewInterceptLogger(&hclog.LoggerOptions{
Name: c.NodeName,
Level: hclog.Trace,
Level: testutil.TestLogLevel,
Output: testutil.NewLogBuffer(t),
})

37
agent/consul/leader_peering.go
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@ -8,7 +8,6 @@ import (
"fmt"
"net"
"github.com/hashicorp/consul/agent/rpc/peering"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/go-memdb"
"github.com/hashicorp/go-multierror"
@ -17,6 +16,7 @@ import (
"google.golang.org/grpc/credentials"
"github.com/hashicorp/consul/agent/pool"
"github.com/hashicorp/consul/agent/rpc/peering"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/proto/pbpeering"
)
@ -50,6 +50,39 @@ func (s *Server) stopPeeringStreamSync() {
// syncPeeringsAndBlock is a long-running goroutine that is responsible for watching
// changes to peerings in the state store and managing streams to those peers.
func (s *Server) syncPeeringsAndBlock(ctx context.Context, logger hclog.Logger, cancelFns map[string]context.CancelFunc) error {
// We have to be careful not to introduce a data race here. We want to
// compare the current known peerings in the state store with known
// connected streams to know when we should TERMINATE stray peerings.
//
// If you read the current peerings from the state store, then read the
// current established streams you could lose the data race and have the
// sequence of events be:
//
// 1. list peerings [A,B,C]
// 2. persist new peering [D]
// 3. accept new stream for [D]
// 4. list streams [A,B,C,D]
// 5. terminate [D]
//
// Which is wrong. If we instead ensure that (4) happens before (1), given
// that you can't get an established stream without first passing a "does
// this peering exist in the state store?" inquiry then this happens:
//
// 1. list streams [A,B,C]
// 2. list peerings [A,B,C]
// 3. persist new peering [D]
// 4. accept new stream for [D]
// 5. terminate []
//
// Or even this is fine:
//
// 1. list streams [A,B,C]
// 2. persist new peering [D]
// 3. accept new stream for [D]
// 4. list peerings [A,B,C,D]
// 5. terminate []
connectedStreams := s.peeringService.ConnectedStreams()
state := s.fsm.State()
// Pull the state store contents and set up to block for changes.
@ -121,7 +154,7 @@ func (s *Server) syncPeeringsAndBlock(ctx context.Context, logger hclog.Logger,
// Clean up active streams of peerings that were deleted from the state store.
// TODO(peering): This is going to trigger shutting down peerings we generated a token for. Is that OK?
for stream, doneCh := range s.peeringService.ConnectedStreams() {
for stream, doneCh := range connectedStreams {
if _, ok := stored[stream]; ok {
// Active stream is in the state store, nothing to do.
continue

4
proto/pbpeering/peering.go
View File

@ -93,6 +93,10 @@ func (x ReplicationMessage_Response_Operation) GoString() string {
return x.String()
}
func (x PeeringState) GoString() string {
return x.String()
}
func (r *TrustBundleReadRequest) CacheInfo() cache.RequestInfo {
info := cache.RequestInfo{
// TODO(peering): Revisit whether this is the token to use once request types accept a token.