grid: launch supervisord with bigger FILENO soft limit

setup.py

@@ -63,7 +63,7 @@ setup(name=name,
           'netaddr>=0.7.5', # to play safely with IPv6 prefixes
           'netifaces', # to fetch information about network devices
           'setuptools', # namespaces
-          'supervisor', # slapgrid uses supervisor to manage processes
+          'supervisor>=3.3.0', # slapgrid uses supervisor to manage processes
           'psutil>=2.0.0',
           'xml_marshaller>=0.9.3', # to unmarshall/marshall python objects to/from
                                    # XML
@@ -75,6 +75,7 @@ setup(name=name,
           'cachecontrol',
           'lockfile',
           'uritemplate', # used by hateoas navigator
+          'resource',
           'subprocess32; python_version<"3"'
         ] + additional_install_requires,
       extras_require=extras_require,

slapos/grid/svcbackend.py

@@ -31,6 +31,7 @@
 import os
 import pkg_resources
 import socket as socketlib
+import resource
 import subprocess
 import stat
 import sys
@@ -175,7 +176,10 @@ def launchSupervisord(instance_root, logger,
   supervisord_argument_list = ['-c', configuration_file]
   if supervisord_additional_argument_list is not None:
     supervisord_argument_list.extend(supervisord_additional_argument_list)
-
+  def preexec_fn():
+    cur_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
+    new_limit = (cur_limit[1], cur_limit[1]) # set the soft limit to the hard limit
+    resource.setrlimit(resource.RLIMIT_NOFILE, new_limit)
   logger.info("Launching supervisord with clean environment.")
   # Extract python binary to prevent shebang size limit
   invocation_list = [sys.executable, '-c']
@@ -188,7 +192,8 @@ def launchSupervisord(instance_root, logger,
                                 env={},
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT,
-                                logger=logger)
+                                logger=logger,
+                                preexec_fn=preexec_fn)
 
   result = supervisord_popen.communicate()[0]
   if supervisord_popen.returncode: