add new page for displaying statistics

everware/__init__.py

@@ -4,3 +4,4 @@
 from .user_spawn_handler import *
 from .user_wait_handler import *
 from .home_handler import *
+from .stats_handler import *

everware/stats_handler.py

@@ -0,0 +1,42 @@
+from jupyterhub.handlers.pages import BaseHandler
+from docker import Client
+from tornado import gen
+
+
+class StatsHandler(BaseHandler):
+    """Handler for the stats page ['/hub/stats'].
+
+    Fills the page with some statistics on everware.
+    """
+    container_statuses = {
+        'running': 'running',
+        'restarting': 'restarting',
+        'paused': 'paused',
+        'exited': 'exited'
+    }
+
+    def initialize(self, stats):
+        """Initialize the handler.
+
+        Parameters
+        ----------
+        stats : dict
+            A dict containing all the stats on the everware instance.
+        """
+        self.stats = stats
+
+    @gen.coroutine
+    def get(self, *args, **kwargs):
+        running_container_count = yield self.get_running_container_count()
+        html = self.render_template(
+            'stats.html',
+            running_container_count=running_container_count,
+            total_launch_count=self.stats['total_launch_count']
+        )
+        self.finish(html)
+
+    @gen.coroutine
+    def get_running_container_count(self):
+        """Get the number of currently running containers."""
+        return len(Client().containers(
+            filters={'status': self.container_statuses['running']}))

everware/user_spawn_handler.py

@@ -5,8 +5,22 @@
 from . import __version__
 from .metrica import MetricaIdsMixin
 
+
 class SpawnHandler(default_handlers.SpawnHandler):
 
+    def initialize(self, stats):
+        """Initialize the handler.
+
+        Collect reference to the everware instance stats for incrementing
+        the field 'total_launch_count'.
+
+        Parameters
+        ----------
+        stats : dict
+            A dict containing the key 'total_launch_count'.
+        """
+        self.stats = stats
+
     def _render_form(self, message=''):
         user = self.get_current_user()
         metrica = MetricaIdsMixin()
@@ -39,6 +53,8 @@ def _spawn(self, user, form_options):
                 user.token = user.spawner.token
         except Exception as e:
             self.log.error("Failed to spawn single-user server with form", exc_info=True)
+        else:
+            self.stats['total_launch_count'] += 1
 
     @web.authenticated
     def get(self):

scripts/everware-server

@@ -2,25 +2,39 @@
 import jupyterhub.handlers.pages as pages
 import jupyterhub.handlers.base as base
 from jupyterhub import app
-from everware import SpawnHandler, UserSpawnHandler, HomeHandler
 import sys
 import warnings
 
 
 class Everware(app.JupyterHub):
     name = 'everware'
 
-    custom_handlers = [
-        ('/hub/user/([^/]+)(/.*)?', UserSpawnHandler),
-        ('/hub/home', HomeHandler),
-        ('/hub/spawn', SpawnHandler)
-    ]
 
     def init_handlers(self):
         super().init_handlers()
-        self.add_handlers(Everware.custom_handlers)
+            ('/hub/user/([^/]+)(/.*)?', UserSpawnHandler),
+            ('/hub/home', HomeHandler),
+            ('/hub/spawn', SpawnHandler, {'stats': self.stats}),
+            ('/hub/stats', StatsHandler, {'stats': self.stats})
+        ])
 
     def add_handlers(self, handlers, replace_existing=True):
+        """Add new handlers.
+
+        Parameters
+        ----------
+        handlers : list-like
+            Contains tuples representing handlers: (url, handler[, init_args]).
+        replace_existing : bool, optional(True)
+            If True, old handlers will be overwritten by new ones on overlapping urls.
+        """
         existing_handler_indices = {handler[0]: i for i, handler in enumerate(self.handlers)}
         for handler in handlers:
             existing_handler_index = existing_handler_indices.get(handler[0])

share/static/html/stats.html

@@ -0,0 +1,10 @@
+{% extends "page.html" %}
+
+{% block main %}
+      <p>
+        Currently running containers: {{ running_container_count }}
+      </p>
+      <p>
+        Total number of launches: {{ total_launch_count }}
+      </p>
+{% endblock %}