--- sites/aura/components/front/releases/1.0a221/lib/python2.7/site-packages/prometheus_client/process_collector.py.ralph	2016-08-18 10:30:57.451278000 +0100
+++ sites/aura/components/front/releases/1.0a221/lib/python2.7/site-packages/prometheus_client/process_collector.py	2016-08-18 11:53:51.811279005 +0100
@@ -3,6 +3,7 @@
 from __future__ import unicode_literals
 
 import os
+import errno
 import time
 import threading
 
@@ -82,9 +83,18 @@
                         max_fds = core.GaugeMetricFamily(self._prefix + 'max_fds',
                                 'Maximum number of open file descriptors.', value=float(line.split()[3]))
                         break
-            open_fds = core.GaugeMetricFamily(self._prefix + 'open_fds',
-                    'Number of open file descriptors.', len(os.listdir(os.path.join(pid, 'fd'))))
-            result.extend([open_fds, max_fds])
+            result.extend([max_fds])
+
+            try:
+                ls = os.listdir(os.path.join(pid, 'fd'))
+            except OSError as e:
+                # Apache MPM prefork, not threaded, has /proc/self owned by root.
+                if e.errno != errno.EACCES:
+                    raise
+            else:
+                open_fds = core.GaugeMetricFamily(self._prefix + 'open_fds',
+                        'Number of open file descriptors.', len(ls))
+                result.extend([open_fds])
         except IOError:
             pass