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Add per-listener connection limits

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Configurable maximum concurrent connections per listener. When the
limit is reached, new connections are closed immediately after accept.
0 means unlimited (default, preserving existing behavior).

Config: Listener gains max_connections field, validated non-negative.

DB: Migration 3 adds listeners.max_connections column.
UpdateListenerMaxConns method for runtime changes via gRPC.
CreateListener updated to persist max_connections on seed.

Server: ListenerState/ListenerData gain MaxConnections. Limit checked
in serve() after Accept but before handleConn — if ActiveConnections
>= MaxConnections, connection is closed and the accept loop continues.
SetMaxConnections method for runtime updates.

Proto: SetListenerMaxConnections RPC added. ListenerStatus gains
max_connections field. Generated code regenerated.

gRPC server: SetListenerMaxConnections implements write-through
(DB first, then in-memory update). GetStatus includes max_connections.

Client: SetListenerMaxConnections method, MaxConnections in
ListenerStatus.

Tests: DB CRUD and UpdateListenerMaxConns, server connection limit
enforcement (accept 2, reject 3rd, close one, accept again), gRPC
SetListenerMaxConnections round-trip with DB persistence, not-found
error handling.

Also updates PROJECT_PLAN.md with phases 6-8 and PROGRESS.md with
tracking for the new features.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Kyle Isom
2026-03-25 16:42:53 -07:00
parent 5bc8f4fc8e
commit 564e0a9c67
16 changed files with 595 additions and 102 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
internal/grpcserver/grpcserver.go
View File

@@ -308,6 +308,28 @@ func (a *AdminServer) RemoveFirewallRule(_ context.Context, req *pb.RemoveFirewa
return &pb.RemoveFirewallRuleResponse{}, nil
}
// SetListenerMaxConnections updates the per-listener connection limit.
func (a *AdminServer) SetListenerMaxConnections(_ context.Context, req *pb.SetListenerMaxConnectionsRequest) (*pb.SetListenerMaxConnectionsResponse, error) {
if req.MaxConnections < 0 {
return nil, status.Error(codes.InvalidArgument, "max_connections must not be negative")
}
ls, err := a.findListener(req.ListenerAddr)
if err != nil {
return nil, err
}
// Write-through: DB first, then memory.
if err := a.store.UpdateListenerMaxConns(ls.ID, req.MaxConnections); err != nil {
return nil, status.Errorf(codes.Internal, "%v", err)
}
ls.SetMaxConnections(req.MaxConnections)
a.logger.Info("connection limit updated", "listener", ls.Addr, "max_connections", req.MaxConnections)
return &pb.SetListenerMaxConnectionsResponse{}, nil
}
// GetStatus returns the proxy's current status.
func (a *AdminServer) GetStatus(_ context.Context, _ *pb.GetStatusRequest) (*pb.GetStatusResponse, error) {
var listeners []*pb.ListenerStatus
@@ -318,6 +340,7 @@ func (a *AdminServer) GetStatus(_ context.Context, _ *pb.GetStatusRequest) (*pb.
RouteCount: int32(len(routes)),
ActiveConnections: ls.ActiveConnections.Load(),
ProxyProtocol: ls.ProxyProtocol,
MaxConnections: ls.MaxConnections,
})
}