Allow configuration via traitlets

Author: jwindgassen

docs/source/standalone.md

@@ -58,6 +58,29 @@ not trigger the login process when accessing the application.
 especially on multi-user systems.
 ```
 
+### Configuration via traitlets
+
+Instead of using the commandline, a standalone proxy can also be configured via a `traitlets` configuration file.
+The configuration file can be loaded by running `jupyter standaloneproxy --config path/to/config.py`.
+
+The options mentioned above can also be configured in the config file:
+
+```python
+# Specify the command to execute
+c.StandaloneProxyServer.command = [
+    "voila", "--no-browser", "--port={port}", "/path/to/some/Notebook.ipynb"
+]
+
+# Specify address and port
+c.StandaloneProxyServer.address = "localhost"
+c.StandaloneProxyServer.port = 8000
+
+# Disable authentication
+c.StandaloneProxyServer.skip_authentication = True
+```
+
+A default config file can be emitted by running `jupyter standaloneproxy --generate-config`
+
 ## Usage with JupyterHub
 
 To launch a standalone proxy with JupyterHub, you need to customize the `Spawner` inside the configuration

jupyter_server_proxy/standalone/app.py

@@ -7,32 +7,29 @@
 from textwrap import dedent
 from urllib.parse import urlparse
 
+from jupyter_core.application import JupyterApp
 from jupyterhub.services.auth import HubOAuthCallbackHandler
 from jupyterhub.utils import make_ssl_context
 from tornado import httpclient, httpserver, ioloop, web
 from tornado.web import RedirectHandler
-from traitlets.config import Application as TraitletsApplication
 from traitlets.traitlets import Bool, Int, Unicode, default, validate
 
 from ..config import ServerProcess
 from .activity import start_activity_update
 from .proxy import make_standalone_proxy
 
 
-class StandaloneProxyServer(TraitletsApplication, ServerProcess):
+class StandaloneProxyServer(JupyterApp, ServerProcess):
     name = "jupyter-standalone-proxy"
     description = """
     Wrap an arbitrary web service so it can be used in place of 'jupyterhub-singleuser' 
     in a JupyterHub setting. 
     
     Usage: jupyter standaloneproxy [options] -- <command>
     
-    The <command> will be executed to start the web service once the proxy receives the first request. The command can
-    contain the placeholders '{{port}}', '{{unix_socket}}' and '{{base_url}}', which will be replaced with the 
-    appropriate values once the application starts.
-    
     For more details, see the jupyter-server-proxy documentation.  
     """
+    examples = "jupyter standaloneproxy -- voila --port={port} --no-browser /path/to/notebook.ipynb"
 
     base_url = Unicode(
         help="""
@@ -152,19 +149,21 @@ def __init__(self, **kwargs):
         # exeptions we do not need, for easier use of the CLI
         # We don't need "command" here, as we will take it from the extra_args
         ignore_traits = [
+            "name",
             "launcher_entry",
             "new_browser_tab",
             "rewrite_response",
             "update_last_activity",
             "command",
         ]
         server_process_aliases = {
-            trait: f"ServerProcess.{trait}"
+            trait: f"StandaloneProxyServer.{trait}"
             for trait in ServerProcess.class_traits(config=True)
             if trait not in ignore_traits and trait not in self.flags
         }
 
         self.aliases = {
+            **super().aliases,
             **server_process_aliases,
             "base_url": "StandaloneProxyServer.base_url",
             "address": "StandaloneProxyServer.address",
@@ -174,6 +173,17 @@ def __init__(self, **kwargs):
             "websocket_max_message_size": "StandaloneProxyServer.websocket_max_message_size",
         }
 
+    def emit_alias_help(self):
+        yield from super().emit_alias_help()
+        yield ""
+
+        # Manually yield the help for command, which we will get from extra_args
+        command_help = StandaloneProxyServer.class_get_trait_help(
+            ServerProcess.command
+        ).split("\n")
+        yield command_help[0].replace("--StandaloneProxyServer.command", "command")
+        yield from command_help[1:]
+
     def get_proxy_base_class(self) -> tuple[type | None, dict]:
         cls, kwargs = super().get_proxy_base_class()
         if cls is None: