promise/plugin: add check_ram_usage promise

Co-authored-by: Xavier Thompson <xavier.thompson@nexedi.com>

slapos/promise/plugin/check_ram_usage.py

+import json
+import os
+import psutil
+import time
+
+from psutil._common import bytes2human
+from .util import JSONPromise
+
+from zope.interface import implementer
+from slapos.grid.promise import interface
+
+@implementer(interface.IPromise)
+class RunPromise(JSONPromise):
+
+  def __init__(self, config):
+
+    super(RunPromise, self).__init__(config)
+
+    self.setPeriodicity(minute=2)
+    self.last_avg_ram_file = self.getConfig(
+      'last-avg-ram-file', 'last_avg')
+
+  def sense(self):
+
+    promise_success = True
+    
+    # Get reference values
+    min_threshold_ram = float(self.getConfig('min-threshold-ram', 500e6)) # ≈500 MB
+    min_avg_ram = float(self.getConfig('min-avg-ram', 1e9)) # ≈1 GB
+    avg_ram_period_sec = int(self.getConfig('avg-ram-period-sec', 0))
+    if avg_ram_period_sec:
+      avg_ram_period = avg_ram_period_sec
+    else:
+      avg_ram_period =  60 * int(self.getConfig('avg-ram-period', 5))
+
+    # Get current RAM usage
+    ram_data = psutil.virtual_memory()
+
+    # Check with min threshold and log error if below it
+    if ram_data.available <= min_threshold_ram:
+      self.logger.error("RAM usage reached critical threshold: %7s "\
+        " (threshold is %7s)" % (bytes2human(ram_data.available), bytes2human(min_threshold_ram)))
+      promise_success = False
+    
+    # Log RAM usage
+    data = json.dumps({'available_ram': ram_data.available})
+    self.json_logger.info("RAM data", extra={'data': data})
+
+    # Get last timestamp (i.e. last modification) of log file
+    try:
+      t = os.path.getmtime(self.last_avg_ram_file)
+    except OSError:
+      t = 0
+    # Get last available RAM from log file since avg_ram_period
+    if (time.time() - t) > avg_ram_period:
+      open(self.last_avg_ram_file, 'w').close()
+      temp_list = self.getJsonLogDataInterval(avg_ram_period)
+      if temp_list:
+        avg_ram = sum(map(lambda x: x['available_ram'], temp_list)) / len(temp_list)
+        if avg_ram < min_avg_ram:
+          self.logger.error("Average RAM usage over the last %s seconds "\
+            "reached threshold: %7s (threshold is %7s)" 
+            % (avg_ram_period, bytes2human(avg_ram), bytes2human(min_avg_ram)))
+          promise_success = False
+      else:
+        self.logger.error("Couldn't read available RAM from log")
+        promise_success = False
+
+    if promise_success:
+      self.logger.info("RAM usage OK")
+
+  def test(self):
+    """
+    Called after sense() if the instance is still converging.
+    Returns success or failure based on sense results.
+
+    In this case, fail if the previous sensor result is negative.
+    """
+    return self._test(result_count=1, failure_amount=1)
+
+
+  def anomaly(self):
+    """
+    Called after sense() if the instance has finished converging.
+    Returns success or failure based on sense results.
+    Failure signals the instance has diverged.
+
+    In this case, fail if two out of the last three results are negative.
+    """
+    return self._anomaly(result_count=3, failure_amount=2)

slapos/test/promise/plugin/test_check_ram_usage.py

+# -*- coding: utf-8 -*-
+##############################################################################
+# Copyright (c) 2018 Vifib SARL and Contributors. All Rights Reserved.
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsibility of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# guarantees and support are strongly advised to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+##############################################################################
+
+import mock
+import os
+import time
+
+from collections import namedtuple
+from slapos.grid.promise import PromiseError
+from slapos.promise.plugin.check_ram_usage import RunPromise
+from . import TestPromisePluginMixin
+
+
+class TestCheckRamUsage(TestPromisePluginMixin):
+
+  promise_name = "monitor-ram-usage.py"
+
+  def setUp(self):
+    super(TestCheckRamUsage, self).setUp()
+
+  def writePromise(self, **kw):
+    super(TestCheckRamUsage, self).writePromise(self.promise_name,
+      "from %s import %s\nextra_config_dict = %r\n"
+      % (RunPromise.__module__, RunPromise.__name__, kw))
+
+  def runPromise(self, summary, failed=False):
+    self.configureLauncher(enable_anomaly=True, force=True)
+    with mock.patch('psutil.virtual_memory', return_value=summary):
+      if failed:
+        self.assertRaises(PromiseError, self.launcher.run)
+      else:
+        self.launcher.run()
+    result = self.getPromiseResult(self.promise_name)['result']
+    self.assertEqual(result['failed'], failed)
+    return result['message']
+
+  def test_ram_ok(self):
+    message = "RAM usage OK"
+    ram_data = namedtuple('ram_data', ['available'])
+    available_ram = {'available':1e9}
+    self.writePromise(**{
+        'last-avg-ram-file':'last_avg_ram_file',
+        'min-threshold-ram': 500e6, # 500MB
+        'min-avg-ram': 100,
+    })
+    self.assertEqual(message, self.runPromise(ram_data(**available_ram)))
+
+  def test_ram_below_threshold_nok(self):
+    message = "RAM usage reached critical threshold:  190.7M  (threshold is  476.8M)"
+    ram_data = namedtuple('ram_data', ['available'])
+    available_ram = {'available': 200e6}
+    self.writePromise(**{
+        'last-avg-ram-file':'last_avg_ram_file',
+        'min-threshold-ram': 500e6, # ≈500MB
+        'min-avg-ram': 100,
+    })
+    self.assertEqual(message, self.runPromise(ram_data(**available_ram)))
+
+  def test_ram_below_average_nok(self):
+    message = "Average RAM usage over the last 1 seconds reached threshold:  100.5B (threshold is  200.0B)"
+    ram_data = namedtuple('ram_data', ['available'])
+    available_ram = {'available': 200}
+    self.writePromise(**{
+        'last-avg-ram-file':'last_avg_ram_file',
+        'min-threshold-ram': 0,
+        'min-avg-ram': 200,
+        'avg-ram-period-sec': 1,
+    })
+    m = self.runPromise(ram_data(**{'available': 1}))
+    time.sleep(1)
+    self.assertEqual(message, self.runPromise(ram_data(**available_ram), failed=True))
+    
+
+if __name__ == '__main__':
+  unittest.main()