Added docs to the prometheus package and the terminal.api_handlers file.

notebook/prometheus/__init__.py

@@ -0,0 +1,4 @@
+"""
+A package containing all the functionality and
+configuration connected to the prometheus metrics
+"""

notebook/terminal/api_handlers.py

@@ -10,6 +10,7 @@ class TerminalRootHandler(APIHandler):
         tm = self.terminal_manager
         terms = [{'name': name} for name in tm.terminals]
         self.finish(json.dumps(terms))
+        # Update the metric below to the length of the list 'terms'
         TERMINAL_CURRENTLY_RUNNING_TOTAL.set(
             len(terms)
         )
@@ -19,6 +20,7 @@ class TerminalRootHandler(APIHandler):
         """POST /terminals creates a new terminal and redirects to it"""
         name, _ = self.terminal_manager.new_named_terminal()
         self.finish(json.dumps({'name': name}))
+        # Increase the metric by one because a new terminal was created
         TERMINAL_CURRENTLY_RUNNING_TOTAL.inc()
 
 
@@ -41,6 +43,7 @@ class TerminalHandler(APIHandler):
             yield tm.terminate(name, force=True)
             self.set_status(204)
             self.finish()
+            # Decrease the metric below by one because a terminal has been shutdown
             TERMINAL_CURRENTLY_RUNNING_TOTAL.dec(1)
         else:
             raise web.HTTPError(404, "Terminal not found: %r" % name)