Some doc fixes

Author: takluyver

docs/source/server-process.rst

@@ -60,8 +60,8 @@ pairs.
 
    * A dictionary of strings that are passed in as the environment to
      the started process, in addition to the environment of the notebook
-     process itself. The strings ``{port}`` and ``{base_url}`` will be
-     replaced as for **command**.
+     process itself. The strings ``{port}``, ``{unix_socket}`` and
+     ``{base_url}`` will be replaced as for **command**.
 
    * A callable that takes any :ref:`callable arguments <server-process/callable-arguments>`,
      and returns a dictionary of strings that are used & treated same as above.
@@ -111,11 +111,14 @@ pairs.
     Jupyter Server Proxy to create a temporary directory to hold the socket,
     ensuring that only the user running Jupyter can connect to it.
 
-    If this is used, the ``{port}`` argument in the command template
-    (see :ref:`server-process-cmd`) will be a filesystem path for this socket
-    instead of a port number. The server should create a Unix socket bound to
-    this path and listen for HTTP requests on it. The ``port`` configuration key
-    will be ignored.
+    If this is used, the ``{unix_socket}`` argument in the command template
+    (see :ref:`server-process-cmd`) will be a filesystem path. The server should
+    create a Unix socket bound to this path and listen for HTTP requests on it.
+    The ``port`` configuration key will be ignored.
+
+    .. note::
+
+       Proxying websockets over a Unix socket requires Tornado >= 6.3.
 
 
 ``mappath``

jupyter_server_proxy/config.py

@@ -146,8 +146,9 @@ class ServerProxy(Configurable):
         Value should be a dictionary with the following keys:
           command
             An optional list of strings that should be the full command to be executed.
-            The optional template arguments {{port}} and {{base_url}} will be substituted with the
-            port the process should listen on and the base-url of the notebook.
+            The optional template arguments {{port}}, {{unix_socket}} and {{base_url}}
+            will be substituted with the port or Unix socket path the process should
+            listen on and the base-url of the notebook.
 
             Could also be a callable. It should return a list.
 
@@ -157,7 +158,7 @@ class ServerProxy(Configurable):
 
           environment
             A dictionary of environment variable mappings. As with the command
-            traitlet, {{port}} and {{base_url}} will be substituted.
+            traitlet, {{port}}, {{unix_socket}} and {{base_url}} will be substituted.
 
             Could also be a callable. It should return a dictionary.
 
@@ -171,6 +172,13 @@ class ServerProxy(Configurable):
           port
             Set the port that the service will listen on. The default is to automatically select an unused port.
 
+          unix_socket
+            If set, the service will listen on a Unix socket instead of a TCP port.
+            Set to True to use a socket in a new temporary folder, or a string
+            path to a socket. This overrides port.
+
+            Proxying websockets over a Unix socket requires Tornado >= 6.3.
+
           mappath
             Map request paths to proxied paths.
             Either a dictionary of request paths to proxied paths,
@@ -202,7 +210,7 @@ class ServerProxy(Configurable):
 
           request_headers_override
             A dictionary of additional HTTP headers for the proxy request. As with
-            the command traitlet, {{port}} and {{base_url}} will be substituted.
+            the command traitlet, {{port}}, {{unix_socket}} and {{base_url}} will be substituted.
 
           rewrite_response
             An optional function to rewrite the response for the given service.