Added Idle Culler

tljh/configurer.py

@@ -9,6 +9,7 @@ FIXME: A strong feeling that JSON Schema should be involved somehow.
 """
 
 import os
+import sys
 
 from .config import CONFIG_FILE, STATE_DIR
 from .yaml import yaml
@@ -55,6 +56,16 @@ default = {
     'user_environment': {
         'default_app': 'classic',
     },
+    'services': {
+        'cull': {
+            'enabled': True,
+            'timeout': 600,
+            'every': 60,
+            'concurrency': 5,
+            'users': False,
+            'max_age': 0
+        }
+    }
 }
 
 def load_config(config_file=CONFIG_FILE):
@@ -86,6 +97,7 @@ def apply_config(config_overrides, c):
     update_user_environment(c, tljh_config)
     update_user_account_config(c, tljh_config)
     update_traefik_api(c, tljh_config)
+    update_services(c, tljh_config)
 
 
 def set_if_not_none(parent, key, value):
@@ -191,6 +203,41 @@ def update_traefik_api(c, config):
     c.TraefikTomlProxy.traefik_api_password = config['traefik_api']['password']
 
 
+def set_cull_idle_service(c, config):
+    """
+    Set Idle Culler service
+    """
+    cull_cmd = [
+       sys.executable, '/srv/src/tljh/cull_idle_servers.py'
+    ]
+    if config['services']['cull']['timeout']:
+        cull_cmd.append('--timeout=%s' % config['services']['cull']['timeout'])
+
+    if config['services']['cull']['every']:
+        cull_cmd.append('--cull-every=%s' % config['services']['cull']['every'])
+
+    if config['services']['cull']['concurrency']:
+        cull_cmd.append('--concurrency=%s' % config['services']['cull']['concurrency'])
+
+    if config['services']['cull']['users']:
+        cull_cmd.append('--cull-users')
+
+    if config['services']['cull']['max_age']:
+        cull_cmd.append('--max-age=%s' % config['services']['cull']['max_age'])
+
+    cull_service = {
+        'name': 'cull-idle',
+        'admin': True,
+        'command': cull_cmd,
+    }
+
+    return cull_service
+
+
+def update_services(c, config):
+    c.JupyterHub.services.append(set_cull_idle_service(c, config))
+
+
 def _merge_dictionaries(a, b, path=None, update=True):
     """
     Merge two dictionaries recursively.

tljh/cull_idle_servers.py

@@ -0,0 +1,342 @@
+#!/usr/bin/env python3
+"""script to monitor and cull idle single-user servers
+
+Imported from https://github.com/jupyterhub/jupyterhub/blob/6b1046697/examples/cull-idle/cull_idle_servers.py
+
+Caveats:
+
+last_activity is not updated with high frequency,
+so cull timeout should be greater than the sum of:
+
+- single-user websocket ping interval (default: 30s)
+- JupyterHub.last_activity_interval (default: 5 minutes)
+
+You can run this as a service managed by JupyterHub with this in your config::
+
+
+    c.JupyterHub.services = [
+        {
+            'name': 'cull-idle',
+            'admin': True,
+            'command': 'python cull_idle_servers.py --timeout=3600'.split(),
+        }
+    ]
+
+Or run it manually by generating an API token and storing it in `JUPYTERHUB_API_TOKEN`:
+
+    export JUPYTERHUB_API_TOKEN=`jupyterhub token`
+    python cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
+"""
+
+from datetime import datetime, timezone
+from functools import partial
+import json
+import os
+
+try:
+    from urllib.parse import quote
+except ImportError:
+    from urllib import quote
+
+import dateutil.parser
+
+from tornado.gen import coroutine, multi
+from tornado.locks import Semaphore
+from tornado.log import app_log
+from tornado.httpclient import AsyncHTTPClient, HTTPRequest
+from tornado.ioloop import IOLoop, PeriodicCallback
+from tornado.options import define, options, parse_command_line
+
+
+def parse_date(date_string):
+    """Parse a timestamp
+
+    If it doesn't have a timezone, assume utc
+
+    Returned datetime object will always be timezone-aware
+    """
+    dt = dateutil.parser.parse(date_string)
+    if not dt.tzinfo:
+        # assume naïve timestamps are UTC
+        dt = dt.replace(tzinfo=timezone.utc)
+    return dt
+
+
+def format_td(td):
+    """
+    Nicely format a timedelta object
+
+    as HH:MM:SS
+    """
+    if td is None:
+        return "unknown"
+    if isinstance(td, str):
+        return td
+    seconds = int(td.total_seconds())
+    h = seconds // 3600
+    seconds = seconds % 3600
+    m = seconds // 60
+    seconds = seconds % 60
+    return f"{h:02}:{m:02}:{seconds:02}"
+
+
+@coroutine
+def cull_idle(url, api_token, inactive_limit, cull_users=False, max_age=0, concurrency=10):
+    """Shutdown idle single-user servers
+
+    If cull_users, inactive *users* will be deleted as well.
+    """
+    auth_header = {
+        'Authorization': 'token %s' % api_token,
+    }
+    req = HTTPRequest(
+        url=url + '/users',
+        headers=auth_header,
+    )
+    now = datetime.now(timezone.utc)
+    client = AsyncHTTPClient()
+
+    if concurrency:
+        semaphore = Semaphore(concurrency)
+        @coroutine
+        def fetch(req):
+            """client.fetch wrapped in a semaphore to limit concurrency"""
+            yield semaphore.acquire()
+            try:
+                return (yield client.fetch(req))
+            finally:
+                yield semaphore.release()
+    else:
+        fetch = client.fetch
+
+    resp = yield fetch(req)
+    users = json.loads(resp.body.decode('utf8', 'replace'))
+    futures = []
+
+    @coroutine
+    def handle_server(user, server_name, server):
+        """Handle (maybe) culling a single server
+
+        Returns True if server is now stopped (user removable),
+        False otherwise.
+        """
+        log_name = user['name']
+        if server_name:
+            log_name = '%s/%s' % (user['name'], server_name)
+        if server.get('pending'):
+            app_log.warning(
+                "Not culling server %s with pending %s",
+                log_name, server['pending'])
+            return False
+
+        if server.get('started'):
+            age = now - parse_date(server['started'])
+        else:
+            # started may be undefined on jupyterhub < 0.9
+            age = None
+
+        # check last activity
+        # last_activity can be None in 0.9
+        if server['last_activity']:
+            inactive = now - parse_date(server['last_activity'])
+        else:
+            # no activity yet, use start date
+            # last_activity may be None with jupyterhub 0.9,
+            # which introduces the 'started' field which is never None
+            # for running servers
+            inactive = age
+
+        should_cull = (inactive is not None and
+                       inactive.total_seconds() >= inactive_limit)
+        if should_cull:
+            app_log.info(
+                "Culling server %s (inactive for %s)",
+                log_name, format_td(inactive))
+
+        if max_age and not should_cull:
+            # only check started if max_age is specified
+            # so that we can still be compatible with jupyterhub 0.8
+            # which doesn't define the 'started' field
+            if age is not None and age.total_seconds() >= max_age:
+                app_log.info(
+                    "Culling server %s (age: %s, inactive for %s)",
+                    log_name, format_td(age), format_td(inactive))
+                should_cull = True
+
+        if not should_cull:
+            app_log.debug(
+                "Not culling server %s (age: %s, inactive for %s)",
+                log_name, format_td(age), format_td(inactive))
+            return False
+
+        req = HTTPRequest(
+            url=url + '/users/%s/server' % quote(user['name']),
+            method='DELETE',
+            headers=auth_header,
+        )
+        resp = yield fetch(req)
+        if resp.code == 202:
+            app_log.warning(
+                "Server %s is slow to stop",
+                log_name,
+            )
+            # return False to prevent culling user with pending shutdowns
+            return False
+        return True
+
+    @coroutine
+    def handle_user(user):
+        """Handle one user.
+
+        Create a list of their servers, and async exec them.  Wait for
+        that to be done, and if all servers are stopped, possibly cull
+        the user.
+        """
+        # shutdown servers first.
+        # Hub doesn't allow deleting users with running servers.
+        # named servers contain the 'servers' dict
+        if 'servers' in user:
+            servers = user['servers']
+        # Otherwise, server data is intermingled in with the user
+        # model
+        else:
+            servers = {}
+            if user['server']:
+                servers[''] = {
+                    'started': user.get('started'),
+                    'last_activity': user['last_activity'],
+                    'pending': user['pending'],
+                    'url': user['server'],
+                }
+        server_futures = [
+            handle_server(user, server_name, server)
+            for server_name, server in servers.items()
+        ]
+        results = yield multi(server_futures)
+        if not cull_users:
+            return
+        # some servers are still running, cannot cull users
+        still_alive = len(results) - sum(results)
+        if still_alive:
+            app_log.debug(
+                "Not culling user %s with %i servers still alive",
+                user['name'], still_alive)
+            return False
+
+        should_cull = False
+        if user.get('created'):
+            age = now - parse_date(user['created'])
+        else:
+            # created may be undefined on jupyterhub < 0.9
+            age = None
+
+        # check last activity
+        # last_activity can be None in 0.9
+        if user['last_activity']:
+            inactive = now - parse_date(user['last_activity'])
+        else:
+            # no activity yet, use start date
+            # last_activity may be None with jupyterhub 0.9,
+            # which introduces the 'created' field which is never None
+            inactive = age
+
+        should_cull = (inactive is not None and
+                       inactive.total_seconds() >= inactive_limit)
+        if should_cull:
+            app_log.info(
+                "Culling user %s (inactive for %s)",
+                user['name'], inactive)
+
+        if max_age and not should_cull:
+            # only check created if max_age is specified
+            # so that we can still be compatible with jupyterhub 0.8
+            # which doesn't define the 'started' field
+            if age is not None and age.total_seconds() >= max_age:
+                app_log.info(
+                    "Culling user %s (age: %s, inactive for %s)",
+                    user['name'], format_td(age), format_td(inactive))
+                should_cull = True
+
+        if not should_cull:
+            app_log.debug(
+                "Not culling user %s (created: %s, last active: %s)",
+                user['name'], format_td(age), format_td(inactive))
+            return False
+
+        req = HTTPRequest(
+            url=url + '/users/%s' % user['name'],
+            method='DELETE',
+            headers=auth_header,
+        )
+        yield fetch(req)
+        return True
+
+    for user in users:
+        futures.append((user['name'], handle_user(user)))
+
+    for (name, f) in futures:
+        try:
+            result = yield f
+        except Exception:
+            app_log.exception("Error processing %s", name)
+        else:
+            if result:
+                app_log.debug("Finished culling %s", name)
+
+
+if __name__ == '__main__':
+    define(
+        'url',
+        default=os.environ.get('JUPYTERHUB_API_URL'),
+        help="The JupyterHub API URL",
+    )
+    define('timeout', default=600, help="The idle timeout (in seconds)")
+    define('cull_every', default=0,
+           help="The interval (in seconds) for checking for idle servers to cull")
+    define('max_age', default=0,
+           help="The maximum age (in seconds) of servers that should be culled even if they are active")
+    define('cull_users', default=False,
+           help="""Cull users in addition to servers.
+                This is for use in temporary-user cases such as tmpnb.""",
+           )
+    define('concurrency', default=10,
+           help="""Limit the number of concurrent requests made to the Hub.
+
+                Deleting a lot of users at the same time can slow down the Hub,
+                so limit the number of API requests we have outstanding at any given time.
+                """
+           )
+
+    parse_command_line()
+    if not options.cull_every:
+        options.cull_every = options.timeout // 2
+    api_token = os.environ['JUPYTERHUB_API_TOKEN']
+
+    try:
+        AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
+    except ImportError as e:
+        app_log.warning(
+            "Could not load pycurl: %s\n"
+            "pycurl is recommended if you have a large number of users.",
+            e)
+
+    loop = IOLoop.current()
+    cull = partial(
+        cull_idle,
+        url=options.url,
+        api_token=api_token,
+        inactive_limit=options.timeout,
+        cull_users=options.cull_users,
+        max_age=options.max_age,
+        concurrency=options.concurrency,
+    )
+    # schedule first cull immediately
+    # because PeriodicCallback doesn't start until the end of the first interval
+    loop.add_callback(cull)
+    # schedule periodic cull
+    pc = PeriodicCallback(cull, 1e3 * options.cull_every)
+    pc.start()
+    try:
+        loop.start()
+    except KeyboardInterrupt:
+        pass

tljh/jupyterhub_config.py

@@ -44,6 +44,8 @@ c.JupyterHub.cleanup_servers = False
 # Use a high port so users can try this on machines with a JupyterHub already present
 c.JupyterHub.hub_port = 15001
 
+c.JupyterHub.services = []
+
 c.TraefikTomlProxy.should_start = False
 
 dynamic_conf_file_path = os.path.join(INSTALL_PREFIX, 'state', 'rules.toml')