Add post-spawn hook

examples/bootstrap-script/README.md

@@ -25,8 +25,11 @@ Another use would be to copy initial content, such as tutorial files or referenc
 You can define your own bootstrap process by implementing a `pre_spawn_hook` on any spawner.
 The Spawner itself is passed as parameter to your hook and you can easily get the contextual information out of the spawning process. 
 
-If you implement a hook, make sure that it is *idempotent*. It will be executed every time 
+Similarly, there may be cases where you would like to clean up after a spawner stops.
-a notebook server is spawned to the user. That means you should somehow 
+You may implement a `post_spawn_hook` that is always executed after the spawner stops.
+
+If you implement a hook, make sure that it is *idempotent*. It will be executed every time
+a notebook server is spawned to the user. That means you should somehow
 ensure that things which should run only once are not running again and again.
 For example, before you create a directory, check if it exists.
 

examples/bootstrap-script/jupyterhub_config.py

@@ -2,6 +2,7 @@
 # create a directory for the user before the spawner starts
 
 import os
+import shutil
 def create_dir_hook(spawner):
     username = spawner.user.name # get the username
     volume_path = os.path.join('/volumes/jupyterhub', username)
@@ -10,8 +11,15 @@ def create_dir_hook(spawner):
         # now do whatever you think your user needs
         # ...
 
-# attach the hook function to the spawner
+def clean_dir_hook(spawner):
+    username = spawner.user.name # get the username
+    temp_path = os.path.join('/volumes/jupyterhub', username, 'temp')
+    if os.path.exists(temp_path) and os.path.isdir(temp_path):
+        shutil.rmtree(temp_path)
+
+# attach the hook functions to the spawner
 c.Spawner.pre_spawn_hook = create_dir_hook
+c.Spawner.post_spawn_hook = clean_dir_hook
 
 # Use the DockerSpawner to serve your users' notebooks
 c.JupyterHub.spawner_class = 'dockerspawner.DockerSpawner'

jupyterhub/spawner.py

@@ -515,6 +515,15 @@ class Spawner(LoggingConfigurable):
         """
     ).tag(config=True)
 
+    post_spawn_hook = Any(
+        help="""
+        An optional hook function that you can implement to do work after
+        the spawner stops.
+
+        This can be set independent of any concrete spawner implementation.
+        """
+    ).tag(config=True)
+
     def load_state(self, state):
         """Restore state of spawner from database.
 
@@ -692,6 +701,13 @@ class Spawner(LoggingConfigurable):
         if self.pre_spawn_hook:
             return self.pre_spawn_hook(self)
 
+    def run_post_spawn_hook(self):
+        """Run the post_spawn_hook if defined"""
+        try:
+            return self.post_spawn_hook(self)
+        except Exception:
+            self.log.exception("post_spawn_hook failed with exception: %s", self)
+
     @property
     def _progress_url(self):
         return self.user.progress_url(self.name)

jupyterhub/user.py

@@ -559,6 +559,8 @@ class User:
         finally:
             spawner.orm_spawner.started = None
             self.db.commit()
+            # trigger post-spawner hook
+            await maybe_future(spawner.run_post_spawn_hook())
             # trigger post-spawner hook on authenticator
             auth = spawner.authenticator
             try: