Merge pull request #3381 from minrk/rm-redundant-args

Stop specifying `--ip` and `--port` on the command-line
jupyterhub · May 21, 2021 · 05f47b1 · 05f47b1
2 parents 6be3160 + 401f583
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diff --git a/docs/source/changelog.md b/docs/source/changelog.md
@@ -986,7 +986,7 @@ Bugfixes on 0.6:
 
 ### [0.6.0] - 2016-04-25
 
-- JupyterHub has moved to a new `jupyterhub` namespace on GitHub and Docker. What was `juptyer/jupyterhub` is now `jupyterhub/jupyterhub`, etc.
+- JupyterHub has moved to a new `jupyterhub` namespace on GitHub and Docker. What was `jupyter/jupyterhub` is now `jupyterhub/jupyterhub`, etc.
 - `jupyterhub/jupyterhub` image on DockerHub no longer loads the jupyterhub_config.py in an ONBUILD step. A new `jupyterhub/jupyterhub-onbuild` image does this
 - Add statsd support, via `c.JupyterHub.statsd_{host,port,prefix}`
 - Update to traitlets 4.1 `@default`, `@observe` APIs for traits

diff --git a/docs/source/reference/spawners.md b/docs/source/reference/spawners.md
@@ -37,14 +37,13 @@ Some examples include:
 Information about the user can be retrieved from `self.user`,
 an object encapsulating the user's name, authentication, and server info.
 
-The return value of `Spawner.start` should be the (ip, port) of the running server.
-
-**NOTE:** When writing coroutines, _never_ `yield` in between a database change and a commit.
+The return value of `Spawner.start` should be the `(ip, port)` of the running server,
+or a full URL as a string.
 
 Most `Spawner.start` functions will look similar to this example:
 
 ```python
-def start(self):
+async def start(self):
     self.ip = '127.0.0.1'
     self.port = random_port()
     # get environment variables,
@@ -56,15 +55,59 @@ def start(self):
     cmd.extend(self.cmd)
     cmd.extend(self.get_args())
 
-    yield self._actually_start_server_somehow(cmd, env)
-    return (self.ip, self.port)
+    await self._actually_start_server_somehow(cmd, env)
+    # url may not match self.ip:self.port, but it could!
+    url = self._get_connectable_url()
+    return url
 ```
 
 When `Spawner.start` returns, the single-user server process should actually be running,
 not just requested. JupyterHub can handle `Spawner.start` being very slow
 (such as PBS-style batch queues, or instantiating whole AWS instances)
 via relaxing the `Spawner.start_timeout` config value.
 
+#### Note on IPs and ports
+
+`Spawner.ip` and `Spawner.port` attributes set the _bind_ url,
+which the single-user server should listen on
+(passed to the single-user process via the `JUPYTERHUB_SERVICE_URL` environment variable).
+The _return_ value is the ip and port (or full url) the Hub should _connect to_.
+These are not necessarily the same, and usually won't be in any Spawner that works with remote resources or containers.
+
+The default for Spawner.ip, and Spawner.port is `127.0.0.1:{random}`,
+which is appropriate for Spawners that launch local processes,
+where everything is on localhost and each server needs its own port.
+For remote or container Spawners, it will often make sense to use a different value,
+such as `ip = '0.0.0.0'` and a fixed port, e.g. `8888`.
+The defaults can be changed in the class,
+preserving configuration with traitlets:
+
+```python
+from traitlets import default
+from jupyterhub.spawner import Spawner
+
+class MySpawner(Spawner):
+    @default("ip")
+    def _default_ip(self):
+        return '0.0.0.0'
+
+    @default("port")
+    def _default_port(self):
+        return 8888
+
+    async def start(self):
+        env = self.get_env()
+        cmd = []
+        # get jupyterhub command to run,
+        # typically ['jupyterhub-singleuser']
+        cmd.extend(self.cmd)
+        cmd.extend(self.get_args())
+
+        remote_server_info = await self._actually_start_server_somehow(cmd, env)
+        url = self.get_public_url_from(remote_server_info)
+        return url
+```
+
 ### Spawner.poll
 
 `Spawner.poll` should check if the spawner is still running.
@@ -207,6 +250,73 @@ Additionally, configurable attributes for your spawner will
 appear in jupyterhub help output and auto-generated configuration files
 via `jupyterhub --generate-config`.
 
+## Environment variables and command-line arguments
+
+Spawners mainly do one thing: launch a command in an environment.
+
+The command-line is constructed from user configuration:
+
+- Spawner.cmd (default: `['jupterhub-singleuser']`)
+- Spawner.args (cli args to pass to the cmd, default: empty)
+
+where the configuration:
+
+```python
+c.Spawner.cmd = ["my-singleuser-wrapper"]
+c.Spawner.args = ["--debug", "--flag"]
+```
+
+would result in spawning the command:
+
+```bash
+my-singleuser-wrapper --debug --flag
+```
+
+The `Spawner.get_args()` method is how Spawner.args is accessed,
+and can be used by Spawners to customize/extend user-provided arguments.
+
+Prior to 2.0, JupyterHub unconditionally added certain options _if specified_ to the command-line,
+such as `--ip={Spawner.ip}` and `--port={Spawner.port}`.
+These have now all been moved to environment variables,
+and from JupyterHub 2.0,
+the command-line launched by JupyterHub is fully specified by overridable configuration `Spawner.cmd + Spawner.args`.
+
+Most process configuration is passed via environment variables.
+Additional variables can be specified via the `Spawner.environment` configuration.
+
+The process environment is returned by `Spawner.get_env`, which specifies the following environment variables:
+
+- JUPYTERHUB*SERVICE_URL - the \_bind* url where the server should launch its http server (`http://127.0.0.1:12345`).
+  This includes Spawner.ip and Spawner.port; _new in 2.0, prior to 2.0 ip,port were on the command-line and only if specified_
+- JUPYTERHUB_SERVICE_PREFIX - the URL prefix the service will run on (e.g. `/user/name/`)
+- JUPYTERHUB_USER - the JupyterHub user's username
+- JUPYTERHUB_SERVER_NAME - the server's name, if using named servers (default server has an empty name)
+- JUPYTERHUB_API_URL - the full url for the JupyterHub API (http://17.0.0.1:8001/hub/api)
+- JUPYTERHUB_BASE_URL - the base url of the whole jupyterhub deployment, i.e. the bit before `hub/` or `user/`,
+  as set by c.JupyterHub.base_url (default: `/`)
+- JUPYTERHUB_API_TOKEN - the API token the server can use to make requests to the Hub.
+  This is also the OAuth client secret.
+- JUPYTERHUB_CLIENT_ID - the OAuth client ID for authenticating visitors.
+- JUPYTERHUB_OAUTH_CALLBACK_URL - the callback URL to use in oauth, typically `/user/:name/oauth_callback`
+
+Optional environment variables, depending on configuration:
+
+- JUPYTERHUB*SSL*[KEYFILE|CERTFILE|CLIENT_CI] - SSL configuration, when internal_ssl is enabled
+- JUPYTERHUB_ROOT_DIR - the root directory of the server (notebook directory), when Spawner.notebook_dir is defined (new in 2.0)
+- JUPYTERHUB_DEFAULT_URL - the default URL for the server (for redirects from /user/:name/),
+  if Spawner.default_url is defined
+  (new in 2.0, previously passed via cli)
+- JUPYTERHUB_DEBUG=1 - generic debug flag, sets maximum log level when Spawner.debug is True
+  (new in 2.0, previously passed via cli)
+- JUPYTERHUB_DISABLE_USER_CONFIG=1 - disable loading user config,
+  sets maximum log level when Spawner.debug is True (new in 2.0,
+  previously passed via cli)
+
+- JUPYTERHUB*[MEM|CPU]*[LIMIT_GUARANTEE] - the values of cpu and memory limits and guarantees.
+  These are not expected to be enforced by the process,
+  but are made available as a hint,
+  e.g. for resource monitoring extensions.
+
 ## Spawners, resource limits, and guarantees (Optional)
 
 Some spawners of the single-user notebook servers allow setting limits or

diff --git a/jupyterhub/singleuser/mixins.py b/jupyterhub/singleuser/mixins.py
@@ -52,6 +52,17 @@
 from ..utils import url_path_join
 
 
+def _bool_env(key):
+    """Cast an environment variable to bool
+
+    0, empty, or unset is False; All other values are True.
+    """
+    if os.environ.get(key, "") in {"", "0"}:
+        return False
+    else:
+        return True
+
+
 # Authenticate requests with the Hub
 
 
@@ -279,6 +290,10 @@ def _default_group(self):
     def _user_changed(self, change):
         self.log.name = change.new
 
+    @default("default_url")
+    def _default_url(self):
+        return os.environ.get("JUPYTERHUB_DEFAULT_URL", "/tree/")
+
     hub_host = Unicode().tag(config=True)
 
     hub_prefix = Unicode('/hub/').tag(config=True)
@@ -361,7 +376,26 @@ def _ip_default(self):
         """,
     ).tag(config=True)
 
-    @validate('notebook_dir')
+    @default("disable_user_config")
+    def _default_disable_user_config(self):
+        return _bool_env("JUPYTERHUB_DISABLE_USER_CONFIG")
+
+    @default("root_dir")
+    def _default_root_dir(self):
+        if os.environ.get("JUPYTERHUB_ROOT_DIR"):
+            proposal = {"value": os.environ["JUPYTERHUB_ROOT_DIR"]}
+            # explicitly call validator, not called on default values
+            return self._notebook_dir_validate(proposal)
+        else:
+            return os.getcwd()
+
+    # notebook_dir is used by the classic notebook server
+    # root_dir is the future in jupyter server
+    @default("notebook_dir")
+    def _default_notebook_dir(self):
+        return self._default_root_dir()
+
+    @validate("notebook_dir", "root_dir")
     def _notebook_dir_validate(self, proposal):
         value = os.path.expanduser(proposal['value'])
         # Strip any trailing slashes
@@ -377,6 +411,13 @@ def _notebook_dir_validate(self, proposal):
             raise TraitError("No such notebook dir: %r" % value)
         return value
 
+    @default('log_level')
+    def _log_level_default(self):
+        if _bool_env("JUPYTERHUB_DEBUG"):
+            return logging.DEBUG
+        else:
+            return logging.INFO
+
     @default('log_datefmt')
     def _log_datefmt_default(self):
         """Exclude date from default date format"""

diff --git a/jupyterhub/spawner.py b/jupyterhub/spawner.py
@@ -39,7 +39,6 @@
 from .traitlets import Callable
 from .traitlets import Command
 from .utils import exponential_backoff
-from .utils import iterate_until
 from .utils import maybe_future
 from .utils import random_port
 from .utils import url_path_join
@@ -232,11 +231,22 @@ def name(self):
     )
 
     ip = Unicode(
-        '',
+        '127.0.0.1',
         help="""
         The IP address (or hostname) the single-user server should listen on.
 
+        Usually either '127.0.0.1' (default) or '0.0.0.0'.
+
         The JupyterHub proxy implementation should be able to send packets to this interface.
+
+        Subclasses which launch remotely or in containers
+        should override the default to '0.0.0.0'.
+
+        .. versionchanged:: 2.0
+            Default changed to '127.0.0.1', from ''.
+            In most cases, this does not result in a change in behavior,
+            as '' was interpreted as 'unspecified',
+            which used the subprocesses' own default, itself usually '127.0.0.1'.
         """,
     ).tag(config=True)
 
@@ -797,8 +807,20 @@ def get_env(self):
             'activity',
         )
         env['JUPYTERHUB_BASE_URL'] = self.hub.base_url[:-4]
+
         if self.server:
+            base_url = self.server.base_url
+            if self.ip or self.port:
+                self.server.ip = self.ip
+                self.server.port = self.port
             env['JUPYTERHUB_SERVICE_PREFIX'] = self.server.base_url
+        else:
+            # this should only occur in mock/testing scenarios
+            base_url = '/'
+
+        proto = 'https' if self.internal_ssl else 'http'
+        bind_url = f"{proto}://{self.ip}:{self.port}{base_url}"
+        env["JUPYTERHUB_SERVICE_URL"] = bind_url
 
         # Put in limit and guarantee info if they exist.
         # Note that this is for use by the humans / notebook extensions in the
@@ -818,6 +840,20 @@ def get_env(self):
             env['JUPYTERHUB_SSL_CERTFILE'] = self.cert_paths['certfile']
             env['JUPYTERHUB_SSL_CLIENT_CA'] = self.cert_paths['cafile']
 
+        if self.notebook_dir:
+            notebook_dir = self.format_string(self.notebook_dir)
+            env["JUPYTERHUB_ROOT_DIR"] = notebook_dir
+
+        if self.default_url:
+            default_url = self.format_string(self.default_url)
+            env["JUPYTERHUB_DEFAULT_URL"] = default_url
+
+        if self.debug:
+            env["JUPYTERHUB_DEBUG"] = "1"
+
+        if self.disable_user_config:
+            env["JUPYTERHUB_DISABLE_USER_CONFIG"] = "1"
+
         # env overrides from config. If the value is a callable, it will be called with
         # one parameter - the current spawner instance - and the return value
         # will be assigned to the environment variable. This will be called at
@@ -829,7 +865,6 @@ def get_env(self):
                 env[key] = value(self)
             else:
                 env[key] = value
-
         return env
 
     async def get_url(self):
@@ -996,35 +1031,16 @@ def get_args(self):
         """Return the arguments to be passed after self.cmd
 
         Doesn't expect shell expansion to happen.
-        """
-        args = []
-
-        if self.ip:
-            args.append('--ip=%s' % _quote_safe(self.ip))
-
-        if self.port:
-            args.append('--port=%i' % self.port)
-        elif self.server and self.server.port:
-            self.log.warning(
-                "Setting port from user.server is deprecated as of JupyterHub 0.7."
-            )
-            args.append('--port=%i' % self.server.port)
-
-        if self.notebook_dir:
-            notebook_dir = self.format_string(self.notebook_dir)
-            args.append('--notebook-dir=%s' % _quote_safe(notebook_dir))
-        if self.default_url:
-            default_url = self.format_string(self.default_url)
-            args.append(
-                '--SingleUserNotebookApp.default_url=%s' % _quote_safe(default_url)
-            )
 
-        if self.debug:
-            args.append('--debug')
-        if self.disable_user_config:
-            args.append('--disable-user-config')
-        args.extend(self.args)
-        return args
+        .. versionchanged:: 2.0
+            Prior to 2.0, JupyterHub passed some options such as
+            ip, port, and default_url to the command-line.
+            JupyterHub 2.0 no longer builds any CLI args
+            other than `Spawner.cmd` and `Spawner.args`.
+            All values that come from jupyterhub itself
+            will be passed via environment variables.
+        """
+        return self.args
 
     def run_pre_spawn_hook(self):
         """Run the pre_spawn_hook if defined"""
@@ -1468,7 +1484,8 @@ async def move_certs(self, paths):
 
     async def start(self):
         """Start the single-user server."""
-        self.port = random_port()
+        if self.port == 0:
+            self.port = random_port()
         cmd = []
         env = self.get_env()