PR: Add command line option to connect to an existing kernel at startup (IPython console)

spyder/app/cli_options.py

@@ -157,6 +157,16 @@ def get_options(argv=None):
         default=None,
         help="Choose a configuration directory to use for Spyder."
     )
+    parser.add_argument(
+        '--connect-to-kernel',
+        type=str,
+        dest="connection_file",
+        default=None,
+        help=(
+            "Connect to an existing kernel whose info is available in a "
+            "kernel-*.json file"
+        )
+    )
 
     parser.add_argument('files', nargs='*')
     options = parser.parse_args(argv)

spyder/plugins/ipythonconsole/plugin.py

@@ -559,7 +559,12 @@ def on_close(self, cancelable=False):
         return self.get_widget().close_all_clients()
 
     def on_mainwindow_visible(self):
-        self.create_new_client(give_focus=False)
+        cli_options = self.get_command_line_options()
+        connection_file = cli_options.connection_file
+        if connection_file is not None:
+            self.create_client_for_kernel(connection_file, give_focus=False)
+        else:
+            self.create_new_client(give_focus=False)
 
     # ---- Private methods
     # -------------------------------------------------------------------------
@@ -715,6 +720,7 @@ def create_client_for_kernel(
         sshkey=None,
         password=None,
         server_id=None,
+        give_focus=False,
         can_close=True,
     ):
         """
@@ -747,7 +753,13 @@ def create_client_for_kernel(
             The created client.
         """
         return self.get_widget().create_client_for_kernel(
-            connection_file, hostname, sshkey, password, server_id, can_close
+            connection_file,
+            hostname,
+            sshkey,
+            password,
+            server_id,
+            give_focus,
+            can_close,
         )
 
     def get_client_for_file(self, filename):

spyder/plugins/ipythonconsole/widgets/main_widget.py

@@ -1726,7 +1726,8 @@ def create_new_client(self, give_focus=True, filename='', special=None,
         return client
 
     def create_client_for_kernel(self, connection_file, hostname, sshkey,
-                                 password, server_id=None, can_close=True):
+                                 password, server_id=None, give_focus=False,
+                                 can_close=True):
         """Create a client connected to an existing kernel."""
         given_name = None
         master_client = None
@@ -1772,6 +1773,7 @@ def create_client_for_kernel(self, connection_file, hostname, sshkey,
             additional_options=self.additional_options(),
             handlers=self.registered_spyder_kernel_handlers,
             server_id=server_id,
+            give_focus=give_focus,
             can_close=can_close,
         )