promise/plugin: Implement check_service_state promise plugin

slapos/promise/plugin/check_service_state.py

+from zope.interface import implementer
+from slapos.grid.promise import interface
+from slapos.grid.promise.generic import GenericPromise
+
+from slapos.grid.svcbackend import getSupervisorRPC
+from slapos.grid.svcbackend import _getSupervisordSocketPath
+
+import os
+
+
+@implementer(interface.IPromise)
+class RunPromise(GenericPromise):
+  def __init__(self, config):
+    super(RunPromise, self).__init__(config)
+    # SR can set custom periodicity
+    self.setPeriodicity(float(self.getConfig('frequency', 2)))
+    self.result_count = int(self.getConfig('result_count', 3))
+    self.failure_amount = int(self.getConfig('failure_amount', 3))
+
+  def sense(self):
+    """
+      Check if a service is in the expected state
+    """
+
+    service = self.getConfig('service')
+    expect = self.getConfig('expect', '')
+
+    if expect not in ("running", "stopped"):
+      self.logger.info("OK service %r is allowed to be in any state (expect = %r)", service, expect)
+      return
+
+    if not service:
+      self.logger.error("ERROR no service is specified")
+      return
+
+    run_directory = self.getConfig('run_directory', os.path.join(self.getPartitionFolder(), "srv/runner/var/run"))
+
+    try:
+      supervisor_rpc = getSupervisorRPC(_getSupervisordSocketPath(run_directory, self.logger))
+
+      with supervisor_rpc as supervisor:
+        state = supervisor.getProcessInfo(service)['statename'].lower()
+        if state != expect:
+          self.logger.error("ERROR service %r is in state %r (expected %r)", service, state, expect)
+        else:
+          self.logger.info("OK service %r is in expected state %r", service, state)
+
+    except Exception as e:
+      self.logger.error("ERROR %r", e, exc_info=True)
+
+  def anomaly(self):
+    return self._anomaly(result_count=self.result_count, failure_amount=self.failure_amount)