class UnitAgent(BaseAgent):
"""An juju Unit Agent.
Provides for the management of a charm, via hook execution in response to
external events in the coordination space (zookeeper).
"""
name = "juju-unit-agent"
@classmethod
def setup_options(cls, parser):
super(UnitAgent, cls).setup_options(parser)
unit_name = os.environ.get("JUJU_UNIT_NAME", "")
parser.add_argument("--unit-name", default=unit_name)
@property
def unit_name(self):
return self.config["unit_name"]
def get_agent_name(self):
return "unit:%s" % self.unit_name
def configure(self, options):
"""Configure the unit agent."""
super(UnitAgent, self).configure(options)
if not options.get("unit_name"):
msg = ("--unit-name must be provided in the command line, "
"or $JUJU_UNIT_NAME in the environment")
raise JujuError(msg)
self.executor = HookExecutor()
self.api_factory = UnitSettingsFactory(
self.executor.get_hook_context,
self.executor.get_invoker,
logging.getLogger("unit.hook.api"))
self.api_socket = None
self.workflow = None
@inlineCallbacks
def start(self):
"""Start the unit agent process."""
service_state_manager = ServiceStateManager(self.client)
# Retrieve our unit and configure working directories.
service_name = self.unit_name.split("/")[0]
self.service_state = yield service_state_manager.get_service_state(
service_name)
self.unit_state = yield self.service_state.get_unit_state(
self.unit_name)
self.unit_directory = os.path.join(
self.config["juju_directory"], "units",
self.unit_state.unit_name.replace("/", "-"))
self.state_directory = os.path.join(
self.config["juju_directory"], "state")
# Setup the server portion of the cli api exposed to hooks.
socket_path = os.path.join(self.unit_directory, HOOK_SOCKET_FILE)
if os.path.exists(socket_path):
os.unlink(socket_path)
from twisted.internet import reactor
self.api_socket = reactor.listenUNIX(socket_path, self.api_factory)
# Setup the unit state's address
address = yield get_unit_address(self.client)
yield self.unit_state.set_public_address(
(yield address.get_public_address()))
yield self.unit_state.set_private_address(
(yield address.get_private_address()))
if self.get_watch_enabled():
yield self.unit_state.watch_hook_debug(self.cb_watch_hook_debug)
# Inform the system, we're alive.
yield self.unit_state.connect_agent()
# Start paying attention to the debug-log setting
if self.get_watch_enabled():
yield self.unit_state.watch_hook_debug(self.cb_watch_hook_debug)
self.lifecycle = UnitLifecycle(
self.client, self.unit_state, self.service_state,
self.unit_directory, self.state_directory, self.executor)
self.workflow = UnitWorkflowState(
self.client, self.unit_state, self.lifecycle, self.state_directory)
# Set up correct lifecycle and executor state given the persistent
# unit workflow state, and fire any starting transitions if necessary.
with (yield self.workflow.lock()):
yield self.workflow.synchronize(self.executor)
if self.get_watch_enabled():
yield self.unit_state.watch_resolved(self.cb_watch_resolved)
yield self.service_state.watch_config_state(
self.cb_watch_config_changed)
yield self.unit_state.watch_upgrade_flag(
self.cb_watch_upgrade_flag)
@inlineCallbacks
def stop(self):
"""Stop the unit agent process."""
if self.lifecycle.running:
yield self.lifecycle.stop(fire_hooks=False, stop_relations=False)
yield self.executor.stop()
if self.api_socket:
yield self.api_socket.stopListening()
yield self.api_factory.stopFactory()
@inlineCallbacks
def cb_watch_resolved(self, change):
"""Update the unit's state, when its resolved.
Resolved operations form the basis of error recovery for unit
workflows. A resolved operation can optionally specify hook
execution. The unit agent runs the error recovery transition
if the unit is not in a running state.
"""
# Would be nice if we could fold this into an atomic
# get and delete primitive.
# Check resolved setting
resolved = yield self.unit_state.get_resolved()
if resolved is None:
returnValue(None)
# Clear out the setting
yield self.unit_state.clear_resolved()
with (yield self.workflow.lock()):
if (yield self.workflow.get_state()) == "started":
returnValue(None)
try:
log.info("Resolved detected, firing retry transition")
if resolved["retry"] == RETRY_HOOKS:
yield self.workflow.fire_transition_alias("retry_hook")
else:
yield self.workflow.fire_transition_alias("retry")
except Exception:
log.exception("Unknown error while transitioning for resolved")
@inlineCallbacks
def cb_watch_hook_debug(self, change):
"""Update the hooks to be debugged when the settings change.
"""
debug = yield self.unit_state.get_hook_debug()
debug_hooks = debug and debug.get("debug_hooks") or None
self.executor.set_debug(debug_hooks)
@inlineCallbacks
def cb_watch_upgrade_flag(self, change):
"""Update the unit's charm when requested.
"""
upgrade_flag = yield self.unit_state.get_upgrade_flag()
if not upgrade_flag:
log.info("No upgrade flag set.")
return
log.info("Upgrade detected")
# Clear the flag immediately; this means that upgrade requests will
# be *ignored* by units which are not "started", and will need to be
# reissued when the units are in acceptable states.
yield self.unit_state.clear_upgrade_flag()
new_id = yield self.service_state.get_charm_id()
old_id = yield self.unit_state.get_charm_id()
if new_id == old_id:
log.info("Upgrade ignored: already running latest charm")
return
with (yield self.workflow.lock()):
state = yield self.workflow.get_state()
if state != "started":
if upgrade_flag["force"]:
yield self.lifecycle.upgrade_charm(
fire_hooks=False, force=True)
log.info("Forced upgrade complete")
return
log.warning(
"Cannot upgrade: unit is in non-started state %s. Reissue "
"upgrade command to try again.", state)
return
log.info("Starting upgrade")
if (yield self.workflow.fire_transition("upgrade_charm")):
log.info("Upgrade complete")
else:
log.info("Upgrade failed")
@inlineCallbacks
def cb_watch_config_changed(self, change):
"""Trigger hook on configuration change"""
# Verify it is running
with (yield self.workflow.lock()):
current_state = yield self.workflow.get_state()
log.debug("Configuration Changed")
if current_state != "started":
log.debug(
"Configuration updated on service in a non-started state")
returnValue(None)
yield self.workflow.fire_transition("configure")
