abci/server: print panic & stack trace to STDERR if logger is not set

Closes #4382

CHANGELOG_PENDING.md

@@ -22,5 +22,6 @@ Friendly reminder, we have a [bug bounty program](https://hackerone.com/tendermi
 
 ### IMPROVEMENTS:
 
+- [abci/server] [\#4719](https://github.com/tendermint/tendermint/pull/4719) Print panic & stack trace to STDERR if logger is not set (@melekes)
 
 ### BUG FIXES:

abci/server/grpc_server.go

@@ -34,25 +34,24 @@ func NewGRPCServer(protoAddr string, app types.ABCIApplicationServer) service.Se
 	return s
 }
 
-// OnStart starts the gRPC service
+// OnStart starts the gRPC service.
 func (s *GRPCServer) OnStart() error {
-	if err := s.BaseService.OnStart(); err != nil {
-		return err
-	}
 	ln, err := net.Listen(s.proto, s.addr)
 	if err != nil {
 		return err
 	}
-	s.Logger.Info("Listening", "proto", s.proto, "addr", s.addr)
+
 	s.listener = ln
 	s.server = grpc.NewServer()
 	types.RegisterABCIApplicationServer(s.server, s.app)
+
+	s.Logger.Info("Listening", "proto", s.proto, "addr", s.addr)
 	go s.server.Serve(s.listener)
+
 	return nil
 }
 
-// OnStop stops the gRPC server
+// OnStop stops the gRPC server.
 func (s *GRPCServer) OnStop() {
-	s.BaseService.OnStop()
 	s.server.Stop()
 }

abci/server/socket_server.go

@@ -5,9 +5,12 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"os"
+	"runtime"
 	"sync"
 
 	"github.com/tendermint/tendermint/abci/types"
+	tmlog "github.com/tendermint/tendermint/libs/log"
 	tmnet "github.com/tendermint/tendermint/libs/net"
 	"github.com/tendermint/tendermint/libs/service"
 )
@@ -16,6 +19,7 @@ import (
 
 type SocketServer struct {
 	service.BaseService
+	isLoggerSet bool
 
 	proto    string
 	addr     string
@@ -42,21 +46,24 @@ func NewSocketServer(protoAddr string, app types.Application) service.Service {
 	return s
 }
 
+func (s *SocketServer) SetLogger(l tmlog.Logger) {
+	s.BaseService.SetLogger(l)
+	s.isLoggerSet = true
+}
+
 func (s *SocketServer) OnStart() error {
-	if err := s.BaseService.OnStart(); err != nil {
-		return err
-	}
 	ln, err := net.Listen(s.proto, s.addr)
 	if err != nil {
 		return err
 	}
+
 	s.listener = ln
 	go s.acceptConnectionsRoutine()
+
 	return nil
 }
 
 func (s *SocketServer) OnStop() {
-	s.BaseService.OnStop()
 	if err := s.listener.Close(); err != nil {
 		s.Logger.Error("Error closing listener", "err", err)
 	}
@@ -105,7 +112,7 @@ func (s *SocketServer) acceptConnectionsRoutine() {
 			if !s.IsRunning() {
 				return // Ignore error from listener closing.
 			}
-			s.Logger.Error("Failed to accept connection: " + err.Error())
+			s.Logger.Error("Failed to accept connection", "err", err)
 			continue
 		}
 
@@ -132,15 +139,15 @@ func (s *SocketServer) waitForClose(closeConn chan error, connID int) {
 	case err == io.EOF:
 		s.Logger.Error("Connection was closed by client")
 	case err != nil:
-		s.Logger.Error("Connection error", "error", err)
+		s.Logger.Error("Connection error", "err", err)
 	default:
 		// never happens
-		s.Logger.Error("Connection was closed.")
+		s.Logger.Error("Connection was closed")
 	}
 
 	// Close the connection
 	if err := s.rmConn(connID); err != nil {
-		s.Logger.Error("Error in closing connection", "error", err)
+		s.Logger.Error("Error closing connection", "err", err)
 	}
 }
 
@@ -153,7 +160,14 @@ func (s *SocketServer) handleRequests(closeConn chan error, conn io.Reader, resp
 		// make sure to recover from any app-related panics to allow proper socket cleanup
 		r := recover()
 		if r != nil {
-			closeConn <- fmt.Errorf("recovered from panic: %v", r)
+			const size = 64 << 10
+			buf := make([]byte, size)
+			buf = buf[:runtime.Stack(buf, false)]
+			err := fmt.Errorf("recovered from panic: %v\n%s", r, buf)
+			if !s.isLoggerSet {
+				fmt.Fprintln(os.Stderr, err)
+			}
+			closeConn <- err
 			s.appMtx.Unlock()
 		}
 	}()
@@ -166,7 +180,7 @@ func (s *SocketServer) handleRequests(closeConn chan error, conn io.Reader, resp
 			if err == io.EOF {
 				closeConn <- err
 			} else {
-				closeConn <- fmt.Errorf("error reading message: %v", err)
+				closeConn <- fmt.Errorf("error reading message: %w", err)
 			}
 			return
 		}
@@ -223,13 +237,13 @@ func (s *SocketServer) handleResponses(closeConn chan error, conn io.Writer, res
 		var res = <-responses
 		err := types.WriteMessage(res, bufWriter)
 		if err != nil {
-			closeConn <- fmt.Errorf("error writing message: %v", err.Error())
+			closeConn <- fmt.Errorf("error writing message: %w", err)
 			return
 		}
 		if _, ok := res.Value.(*types.Response_Flush); ok {
 			err = bufWriter.Flush()
 			if err != nil {
-				closeConn <- fmt.Errorf("error flushing write buffer: %v", err.Error())
+				closeConn <- fmt.Errorf("error flushing write buffer: %w", err)
 				return
 			}
 		}