Add very basic Linux control groups support

docs/api.rst

@@ -231,7 +231,8 @@ Process Control
              'exitstatus':     0,
              'stdout_logfile': '/path/to/stdout-log',
              'stderr_logfile': '/path/to/stderr-log',
-             'pid':            1}
+             'pid':            1,
+             'has_cgroups'     0}
 
         .. describe:: name
 
@@ -286,6 +287,10 @@ Process Control
             UNIX process ID (PID) of the process, or 0 if the process is not
             running.
 
+        .. describe:: has_cgroups
+
+            1 if the process was configured to attach to at least one control
+            group, or 0 if not.
 
     .. automethod:: getAllProcessInfo
 

supervisor/options.py

@@ -794,6 +794,7 @@ def processes_from_section(self, parser, section, group_name,
         serverurl = get(section, 'serverurl', None)
         if serverurl and serverurl.strip().upper() == 'AUTO':
             serverurl = None
+        cgroups = list_of_strings(get(section, 'cgroups', None))
 
         umask = get(section, 'umask', None)
         if umask is not None:
@@ -883,7 +884,8 @@ def processes_from_section(self, parser, section, group_name,
                 exitcodes=exitcodes,
                 redirect_stderr=redirect_stderr,
                 environment=environment,
-                serverurl=serverurl)
+                serverurl=serverurl,
+                cgroups=cgroups)
 
             programs.append(pconfig)
 
@@ -1600,7 +1602,7 @@ class ProcessConfig(Config):
         'stderr_logfile_backups', 'stderr_logfile_maxbytes',
         'stderr_events_enabled',
         'stopsignal', 'stopwaitsecs', 'stopasgroup', 'killasgroup',
-        'exitcodes', 'redirect_stderr' ]
+        'exitcodes', 'redirect_stderr', 'cgroups' ]
     optional_param_names = [ 'environment', 'serverurl' ]
 
     def __init__(self, options, **params):

supervisor/process.py

@@ -289,6 +289,19 @@ def _spawn_as_child(self, filename, argv):
             options.setpgrp()
             self._prepare_child_fds()
             # sending to fd 2 will put this output in the stderr log
+
+            # Attach the child to cgroups before dropping privileges
+            # (may need to be root to do this).
+            msg = self.attach_cgroups()
+            if msg:
+                cgroups = self.config.cgroups
+                s = 'supervisor: error attaching process to cgroups %s ' % cgroups
+                options.write(2, s)
+                options.write(2, "(%s)\n" % msg)
+                # It would be great to actually affect parent state here
+                # (i.e. the parent should know that we haven't actually
+                # attached), but this only logs.
+
             msg = self.set_uid()
             if msg:
                 uid = self.config.uid
@@ -491,6 +504,24 @@ def set_uid(self):
         msg = self.config.options.dropPrivileges(self.config.uid)
         return msg
 
+    def attach_cgroups(self):
+        # Doesn't undo in the event of partial failure (e.g. attach succeeds
+        # for one but not the other).
+        for cgroup in self.config.cgroups:
+            tasks_path = os.path.join(cgroup, "tasks")
+            if not os.path.isfile(tasks_path):
+                return "Can't find cgroup path %s" % tasks_path
+            try:
+                tasks = open(tasks_path, "w")
+                try:
+                    # We assume that we're only called during process creation,
+                    # so we're single-threaded and can write just our PID.
+                    tasks.write(str(self.config.options.get_pid()))
+                finally:
+                    tasks.close()
+            except IOError:
+                return "Couldn't attach process to cgroup %s" % tasks_path
+
     def __cmp__(self, other):
         # sort by priority
         return cmp(self.config.priority, other.config.priority)

supervisor/rpcinterface.py

@@ -527,6 +527,7 @@ def getProcessInfo(self, name):
             'stdout_logfile':stdout_logfile,
             'stderr_logfile':stderr_logfile,
             'pid':process.pid,
+            'has_cgroups':int(len(process.config.cgroups) > 0),
             }
 
         description = self._interpretProcessInfo(info)

supervisor/tests/base.py

@@ -484,7 +484,7 @@ def __init__(self, options, name, command, directory=None, umask=None,
                  stderr_logfile_backups=0, stderr_logfile_maxbytes=0,
                  redirect_stderr=False,
                  stopsignal=None, stopwaitsecs=10, stopasgroup=False, killasgroup=False,
-                 exitcodes=(0,2), environment=None, serverurl=None):
+                 exitcodes=(0,2), environment=None, serverurl=None, cgroups=[]):
         self.options = options
         self.name = name
         self.command = command
@@ -518,6 +518,7 @@ def __init__(self, options, name, command, directory=None, umask=None,
         self.umask = umask
         self.autochildlogs_created = False
         self.serverurl = serverurl
+        self.cgroups = cgroups
 
     def create_autochildlogs(self):
         self.autochildlogs_created = True

supervisor/tests/test_options.py

@@ -263,6 +263,7 @@ def test_options(self):
         numprocs = 2
         command = /bin/cat
         autorestart=unexpected
+        cgroups=/path/one,/path/two
         """ % {'tempdir':tempfile.gettempdir()})
 
         from supervisor import datatypes
@@ -322,6 +323,7 @@ def test_options(self):
         self.assertEqual(proc1.directory, '/tmp')
         self.assertEqual(proc1.umask, 002)
         self.assertEqual(proc1.environment, dict(FAKE_ENV_VAR='/some/path'))
+        self.assertEqual(proc1.cgroups, [])
 
         cat2 = options.process_group_configs[1]
         self.assertEqual(cat2.name, 'cat2')
@@ -343,6 +345,7 @@ def test_options(self):
         self.assertEqual(proc2.stdout_logfile_backups, 2)
         self.assertEqual(proc2.exitcodes, [0,2])
         self.assertEqual(proc2.directory, None)
+        self.assertEqual(proc2.cgroups, [])
 
         cat3 = options.process_group_configs[2]
         self.assertEqual(cat3.name, 'cat3')
@@ -364,6 +367,7 @@ def test_options(self):
         self.assertEqual(proc3.stopsignal, signal.SIGTERM)
         self.assertEqual(proc3.stopasgroup, True)
         self.assertEqual(proc3.killasgroup, True)
+        self.assertEqual(proc3.cgroups, [])
 
         cat4 = options.process_group_configs[3]
         self.assertEqual(cat4.name, 'cat4')
@@ -386,6 +390,7 @@ def test_options(self):
         self.assertEqual(proc4_a.stopsignal, signal.SIGTERM)
         self.assertEqual(proc4_a.stopasgroup, False)
         self.assertEqual(proc4_a.killasgroup, False)
+        self.assertEqual(proc4_a.cgroups, ["/path/one", "/path/two"])
 
         proc4_b = cat4.process_configs[1]
         self.assertEqual(proc4_b.name, 'fleeb_1')
@@ -403,6 +408,7 @@ def test_options(self):
         self.assertEqual(proc4_b.stopsignal, signal.SIGTERM)
         self.assertEqual(proc4_b.stopasgroup, False)
         self.assertEqual(proc4_b.killasgroup, False)
+        self.assertEqual(proc4_b.cgroups, ["/path/one", "/path/two"])
 
         here = os.path.abspath(os.getcwd())
         self.assertEqual(instance.uid, 0)
@@ -704,6 +710,7 @@ def test_processes_from_section(self):
         environment = KEY1=val1,KEY2=val2,KEY3=%(process_num)s
         numprocs = 2
         process_name = %(group_name)s_%(program_name)s_%(process_num)02d
+        cgroups = foo,bar
         """)
         from supervisor.options import UnhosedConfigParser
         config = UnhosedConfigParser()
@@ -730,6 +737,7 @@ def test_processes_from_section(self):
         self.assertEqual(pconfig.redirect_stderr, False)
         self.assertEqual(pconfig.environment,
                          {'KEY1':'val1', 'KEY2':'val2', 'KEY3':'0'})
+        self.assertEqual(pconfig.cgroups, ["foo", "bar"])
 
     def test_processes_from_section_host_node_name_expansion(self):
         instance = self._makeOne()
@@ -1445,7 +1453,7 @@ def _makeOne(self, *arg, **kw):
                      'stderr_events_enabled',
                      'stderr_logfile_backups', 'stderr_logfile_maxbytes',
                      'stopsignal', 'stopwaitsecs', 'stopasgroup', 'killasgroup', 'exitcodes',
-                     'redirect_stderr', 'environment'):
+                     'redirect_stderr', 'environment', 'cgroups'):
             defaults[name] = name
         defaults.update(kw)
         return self._getTargetClass()(*arg, **defaults)
@@ -1519,7 +1527,7 @@ def _makeOne(self, *arg, **kw):
                      'stderr_events_enabled',
                      'stderr_logfile_backups', 'stderr_logfile_maxbytes',
                      'stopsignal', 'stopwaitsecs', 'stopasgroup', 'killasgroup', 'exitcodes',
-                     'redirect_stderr', 'environment'):
+                     'redirect_stderr', 'environment', 'cgroups'):
             defaults[name] = name
         defaults.update(kw)
         return self._getTargetClass()(*arg, **defaults)

supervisor/tests/test_process.py

@@ -904,6 +904,29 @@ def test_set_uid(self):
         self.assertEqual(options.privsdropped, 1)
         self.assertEqual(msg, None)
 
+    def test_attach_cgroups(self):
+        cgroups = ["/tmp/test_cg1", "/tmp/test_cg2"]
+        for cg in cgroups:
+            if os.path.exists(cg):
+                os.rmdir(cg)
+            os.makedirs(cg)
+            open(os.path.join(cg, "tasks"), "w").close()
+
+        options = DummyOptions()
+        config = DummyPConfig(options, 'test', '/test', cgroups=cgroups)
+        instance = self._makeOne(config)
+        msg = instance.attach_cgroups()
+        for cg in cgroups:
+            tasks_path = os.path.join(cg, "tasks")
+            tasks = open(tasks_path)
+            try:
+                self.assertEqual(tasks.read().strip(), str(os.getpid()))
+            finally:
+                tasks.close()
+            os.remove(tasks_path)
+            os.rmdir(cg)
+        self.assertEqual(msg, None)
+
     def test_cmp_bypriority(self):
         options = DummyOptions()
         config = DummyPConfig(options, 'notthere', '/notthere',

supervisor/tests/test_supervisord.py

@@ -261,7 +261,8 @@ def make_pconfig(name, command, **params):
                 'stopsignal': None, 'stopwaitsecs': 10,
                 'stopasgroup': False,
                 'killasgroup': False,
-                'exitcodes': (0,2), 'environment': None, 'serverurl': None }
+                'exitcodes': (0,2), 'environment': None, 'serverurl': None,
+                'cgroups': None }
             result.update(params)
             return ProcessConfig(options, **result)