""" Copyright 2013 Rackspace, Inc. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. """ import collections import random import threading import time from cherrypy import wsgiserver import pkg_resources from stevedore import driver import structlog from teeth_rest import encoding from teeth_rest import errors as rest_errors from teeth_agent import api from teeth_agent import base from teeth_agent import errors from teeth_agent import hardware from teeth_agent import overlord_agent_api class TeethAgentStatus(encoding.Serializable): def __init__(self, mode, started_at, version): self.mode = mode self.started_at = started_at self.version = version def serialize(self, view): """Turn the status into a dict.""" return collections.OrderedDict([ ('mode', self.mode), ('started_at', self.started_at), ('version', self.version), ]) class TeethAgentHeartbeater(threading.Thread): # If we could wait at most N seconds between heartbeats (or in case of an # error) we will instead wait r x N seconds, where r is a random value # between these multipliers. min_jitter_multiplier = 0.3 max_jitter_multiplier = 0.6 # Exponential backoff values used in case of an error. In reality we will # only wait a portion of either of these delays based on the jitter # multipliers. initial_delay = 1.0 max_delay = 300.0 backoff_factor = 2.7 def __init__(self, agent): super(TeethAgentHeartbeater, self).__init__() self.agent = agent self.hardware = hardware.get_manager() self.api = overlord_agent_api.APIClient(agent.api_url) self.log = structlog.get_logger(api_url=agent.api_url) self.stop_event = threading.Event() self.error_delay = self.initial_delay def run(self): # The first heartbeat happens now self.log.info('starting heartbeater') interval = 0 while not self.stop_event.wait(interval): next_heartbeat_by = self.do_heartbeat() interval_multiplier = random.uniform(self.min_jitter_multiplier, self.max_jitter_multiplier) interval = (next_heartbeat_by - time.time()) * interval_multiplier self.log.info('sleeping before next heartbeat', interval=interval) def do_heartbeat(self): try: deadline = self.api.heartbeat( hardware_info=self.hardware.list_hardware_info(), version=self.agent.version, mode=self.agent.get_mode_name()) self.error_delay = self.initial_delay self.log.info('heartbeat successful') except Exception as e: self.log.error('error sending heartbeat', exception=e) deadline = time.time() + self.error_delay self.error_delay = min(self.error_delay * self.backoff_factor, self.max_delay) pass return deadline def stop(self): self.log.info('stopping heartbeater') self.stop_event.set() return self.join() class TeethAgent(object): def __init__(self, api_url, listen_address, ipaddr): self.api_url = api_url self.listen_address = listen_address self.ipaddr = ipaddr self.mode_implementation = None self.version = pkg_resources.get_distribution('teeth-agent').version self.api = api.TeethAgentAPIServer(self) self.command_results = collections.OrderedDict() self.heartbeater = TeethAgentHeartbeater(self) self.hardware = hardware.get_manager() self.command_lock = threading.Lock() self.log = structlog.get_logger() self.started_at = None def get_mode_name(self): if self.mode_implementation: return self.mode_implementation.name else: return 'NONE' def get_status(self): """Retrieve a serializable status.""" return TeethAgentStatus( mode=self.get_mode_name(), started_at=self.started_at, version=self.version ) def get_agent_mac_addr(self): return self.hardware.get_primary_mac_address() def list_command_results(self): return self.command_results.values() def get_command_result(self, result_id): try: return self.command_results[result_id] except KeyError: raise errors.RequestedObjectNotFoundError('Command Result', result_id) def _split_command(self, command_name): command_parts = command_name.split('.', 1) if len(command_parts) != 2: raise errors.InvalidCommandError( 'Command name must be of the form .') return (command_parts[0], command_parts[1]) def _verify_mode(self, mode_name, command_name): if not self.mode_implementation: try: self.mode_implementation = _load_mode_implementation(mode_name) except Exception: raise errors.InvalidCommandError( 'Unknown mode: {}'.format(mode_name)) elif self.get_mode_name().lower() != mode_name: raise errors.InvalidCommandError( 'Agent is already in {} mode'.format(self.get_mode_name())) def execute_command(self, command_name, **kwargs): """Execute an agent command.""" with self.command_lock: mode_part, command_part = self._split_command(command_name) self._verify_mode(mode_part, command_part) if len(self.command_results) > 0: last_command = self.command_results.values()[-1] if not last_command.is_done(): raise errors.CommandExecutionError('agent is busy') try: result = self.mode_implementation.execute(command_part, **kwargs) except rest_errors.InvalidContentError as e: # Any command may raise a InvalidContentError which will be # returned to the caller directly. raise e except Exception as e: # Other errors are considered command execution errors, and are # recorded as an result = base.SyncCommandResult(command_name, kwargs, False, e) self.command_results[result.id] = result return result def run(self): """Run the Teeth Agent.""" self.started_at = time.time() self.heartbeater.start() server = wsgiserver.CherryPyWSGIServer(self.listen_address, self.api) try: server.start() except BaseException as e: self.log.error('shutting down', exception=e) server.stop() self.heartbeater.stop() def _load_mode_implementation(mode_name): mgr = driver.DriverManager( namespace='teeth_agent.modes', name=mode_name.lower(), invoke_on_load=True, invoke_args=[], ) return mgr.driver def build_agent(api_url, listen_host, listen_port, ipaddr): return TeethAgent(api_url, (listen_host, listen_port), ipaddr)