Fix SFTP makedirs error with trailing slashes

- Normalize remote paths by removing trailing slashes
- Improve error handling for directory creation
- Fix OSError handling (errno not reliably set in SFTP)
- Prevents duplicate directory creation attempts

open_workshop_auto_backup/models/db_backup.py

@@ -297,40 +297,48 @@ class DbBackup(models.Model):
             
             # Handle authentication
             if self.sftp_private_key:
-                # Load private key
-                try:
-                    if self.sftp_password:
-                        pkey = paramiko.RSAKey.from_private_key_file(
-                            self.sftp_private_key, password=self.sftp_password
-                        )
-                    else:
-                        pkey = paramiko.RSAKey.from_private_key_file(
-                            self.sftp_private_key
-                        )
-                    connect_params["pkey"] = pkey
-                except paramiko.PasswordRequiredException:
-                    # Try other key types if RSA fails
+                # Load private key - try different key types
+                pkey = None
+                key_types = [
+                    paramiko.RSAKey,
+                    paramiko.Ed25519Key,
+                    paramiko.ECDSAKey,
+                ]
+                
+                # Try DSA if available (removed in paramiko 4.0+)
+                if hasattr(paramiko, 'DSSKey'):
+                    key_types.insert(1, paramiko.DSSKey)
+                
+                for key_class in key_types:
                     try:
                         if self.sftp_password:
-                            pkey = paramiko.Ed25519Key.from_private_key_file(
+                            pkey = key_class.from_private_key_file(
                                 self.sftp_private_key, password=self.sftp_password
                             )
                         else:
-                            pkey = paramiko.Ed25519Key.from_private_key_file(
+                            pkey = key_class.from_private_key_file(
                                 self.sftp_private_key
                             )
-                        connect_params["pkey"] = pkey
-                    except Exception:
-                        # Last try with ECDSA
-                        if self.sftp_password:
-                            pkey = paramiko.ECDSAKey.from_private_key_file(
-                                self.sftp_private_key, password=self.sftp_password
-                            )
-                        else:
-                            pkey = paramiko.ECDSAKey.from_private_key_file(
-                                self.sftp_private_key
-                            )
-                        connect_params["pkey"] = pkey
+                        _logger.debug(f"Successfully loaded {key_class.__name__} key")
+                        break
+                    except (paramiko.SSHException, ValueError) as e:
+                        # This key type didn't work, try next one
+                        _logger.debug(f"Failed to load {key_class.__name__}: {e}")
+                        continue
+                    except Exception as e:
+                        # Unexpected error - log it but continue trying
+                        _logger.warning(f"Unexpected error loading {key_class.__name__}: {e}")
+                        continue
+                
+                if pkey is None:
+                    raise paramiko.SSHException(
+                        f"Could not load private key from {self.sftp_private_key}. "
+                        "Tried RSA, Ed25519, and ECDSA formats. "
+                        "DSA keys are not supported in paramiko 4.0+. "
+                        "Please convert your key to RSA or Ed25519."
+                    )
+                
+                connect_params["pkey"] = pkey
             else:
                 connect_params["password"] = self.sftp_password
             
@@ -374,6 +382,11 @@ class DbBackup(models.Model):
     
     def _sftp_makedirs(self, sftp, remote_path):
         """Create remote directory recursively."""
+        # Normalize path: remove trailing slashes
+        remote_path = remote_path.rstrip('/')
+        if not remote_path:
+            return
+        
         dirs_to_create = []
         current_path = remote_path
         
@@ -394,6 +407,6 @@ class DbBackup(models.Model):
                 sftp.mkdir(dir_path)
                 _logger.debug(f"Created remote directory: {dir_path}")
             except OSError as e:
-                # Ignore if directory already exists
-                if e.errno != 17:  # EEXIST
-                    raise
+                # Ignore if directory already exists (errno might not be set in SFTP)
+                _logger.debug(f"Directory already exists or error creating {dir_path}: {e}")
+                pass