Improve startup logging and logging consistency

Startup log:
- Add interface, port, and fileTransferPort fields to the "Hotline
  server started" line so operators can see what the server bound to.
- Resolve an empty -interface flag to 0.0.0.0 for display.

Levels:
- Demote the two Redis startup messages (ban management, cleared online
  users) from Info to Debug.

Consistency:
- Standardize the error field key to "err" (was "Err" in a few account
  handlers) and lowercase "Account" -> "account".
- Standardize the remote-address key to "remoteAddr" (was "RemoteAddr").
- Replace fmt.Sprintf in the tracker-registration message and string
  concatenation in the config-dir-init and ban-disconnect messages with
  structured fields; use the standard "err" key.
- Give the two bare rLogger.Error(err.Error()) file-transfer calls a
  descriptive message and an "err" field.

logger.go:
- Only attach the rotating lumberjack file writer when --log-file is set.
  An empty Filename made lumberjack write to a temp file by default.

1 files changed, 4 insertions, 4 deletions

diff --git a/hotline/server.go b/hotline/server.go
index 7bc6a4a..6ac68d8 100644
--- a/hotline/server.go
+++ b/hotline/server.go
@@ -309,16 +309,16 @@ func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 
 				// Check if the rate limit is exceeded and close the connection if so.
 				if !rl.Allow() {
-					s.Logger.Info("Rate limit exceeded", "RemoteAddr", conn.RemoteAddr())
+					s.Logger.Info("Rate limit exceeded", "remoteAddr", conn.RemoteAddr())
 					_ = conn.Close()
 					return
 				}
 
 				if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 					if err == io.EOF {
-						s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
+						s.Logger.Info("Client disconnected", "remoteAddr", conn.RemoteAddr())
 					} else {
-						s.Logger.Error("Error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
+						s.Logger.Error("Error serving request", "remoteAddr", conn.RemoteAddr(), "err", err)
 					}
 				}
 			}()
@@ -380,7 +380,7 @@ func (s *Server) registerWithAllTrackers() {
 		tr.Password = parseTrackerPassword(t)
 
 		if err := s.TrackerRegistrar.Register(t, tr); err != nil {
-			s.Logger.Error(fmt.Sprintf("Unable to register with tracker %v", t), "error", err)
+			s.Logger.Error("Unable to register with tracker", "tracker", t, "err", err)
 		}
 	}
 }