python3-maas-provisioningserver 2.4.0~beta2-6865-gec43e47e6-0ubuntu1 / usr / lib / python3 / dist-packages / provisioningserver / rpc / power.py

# Copyright 2014-2016 Canonical Ltd.  This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).

"""Power control."""

__all__ = [
    "power_action_registry",
    "power_state_update",
    "maybe_change_power_state",
]

from datetime import timedelta
from functools import partial
import sys

from provisioningserver.drivers.power import (
    get_error_message,
    PowerError,
)
from provisioningserver.drivers.power.registry import PowerDriverRegistry
from provisioningserver.events import (
    EVENT_TYPES,
    send_node_event,
)
from provisioningserver.logger import (
    get_maas_logger,
    LegacyLogger,
)
from provisioningserver.rpc import getRegionClient
from provisioningserver.rpc.exceptions import (
    NoSuchNode,
    PowerActionAlreadyInProgress,
    PowerActionFail,
)
from provisioningserver.rpc.region import (
    MarkNodeFailed,
    UpdateNodePowerState,
)
from provisioningserver.utils.twisted import (
    asynchronous,
    callOut,
    deferred,
    deferWithTimeout,
)
from twisted.internet import reactor
from twisted.internet.defer import (
    CancelledError,
    DeferredList,
    DeferredSemaphore,
    inlineCallbacks,
    returnValue,
    succeed,
)
from twisted.internet.task import deferLater


maaslog = get_maas_logger("power")
log = LegacyLogger()

# Timeout for change_power_state(). We set it to 5 minutes by default,
# but it would be lovely if this was configurable. This is only a backstop
# meant to cope with broken BMCs.
CHANGE_POWER_STATE_TIMEOUT = timedelta(minutes=5).total_seconds()

# We could use a Registry here, but it seems kind of like overkill.
power_action_registry = {}


@asynchronous
def power_state_update(system_id, state):
    """Report to the region about a node's power state.

    :param system_id: The system ID for the node.
    :param state: Typically "on", "off", or "error".
    """
    client = getRegionClient()
    return client(
        UpdateNodePowerState,
        system_id=system_id,
        power_state=state)


@asynchronous(timeout=15)
@inlineCallbacks
def power_change_failure(system_id, hostname, power_change, message):
    """Report a node that for which power control has failed."""
    assert power_change in ['on', 'off', 'cycle'], (
        "Unknown power change: %s" % power_change)
    maaslog.error(
        "Error changing power state (%s) of node: %s (%s)",
        power_change, hostname, system_id)
    client = getRegionClient()
    yield client(
        MarkNodeFailed,
        system_id=system_id,
        error_description=message,
    )
    if power_change == 'on':
        event_type = EVENT_TYPES.NODE_POWER_ON_FAILED
    elif power_change == 'off':
        event_type = EVENT_TYPES.NODE_POWER_OFF_FAILED
    elif power_change == 'cycle':
        event_type = EVENT_TYPES.NODE_POWER_CYCLE_FAILED
    yield send_node_event(event_type, system_id, hostname, message)


@asynchronous
def perform_power_driver_change(
        system_id, hostname, power_type, power_change, context):
    """Execute power driver `power_change` method.

    On failure the node will be marked as broken and the error will be
    re-raised to the caller.
    """
    power_driver = PowerDriverRegistry.get_item(power_type)

    if power_change == 'on':
        d = power_driver.on(system_id, context)
    elif power_change == 'off':
        d = power_driver.off(system_id, context)
    elif power_change == 'cycle':
        d = power_driver.cycle(system_id, context)

    def power_change_failed(failure):
        message = "Power %s for the node failed: %s" % (
            power_change, get_error_message(failure.value))
        df = power_change_failure(system_id, hostname, power_change, message)
        df.addCallback(lambda _: failure)  # Propagate the original error.
        return df

    return d.addErrback(power_change_failed)


@asynchronous
@inlineCallbacks
def power_change_success(system_id, hostname, power_change):
    """Report about a successful node power state change.

    This updates the region's record of the node's power state, logs to the
    MAAS log, and appends to the node's event log.

    :param system_id: The system ID for the node.
    :param hostname: The node's hostname, used in messages.
    :param power_change: "on" or "off".
    """
    assert power_change in ['on', 'off'], (
        "Unknown power change: %s" % power_change)
    yield power_state_update(system_id, power_change)
    maaslog.info(
        "Changed power state (%s) of node: %s (%s)",
        power_change, hostname, system_id)
    # Emit success event.
    if power_change == 'on':
        event_type = EVENT_TYPES.NODE_POWERED_ON
    elif power_change == 'off':
        event_type = EVENT_TYPES.NODE_POWERED_OFF
    yield send_node_event(event_type, system_id, hostname)


@asynchronous
@inlineCallbacks
def power_change_starting(system_id, hostname, power_change):
    """Report about a node power state change starting.

    This logs to the MAAS log, and appends to the node's event log.

    :param system_id: The system ID for the node.
    :param hostname: The node's hostname, used in messages.
    :param power_change: "on", "off", or "cycle".
    """
    assert power_change in ['on', 'off', 'cycle'], (
        "Unknown power change: %s" % power_change)
    maaslog.info(
        "Changing power state (%s) of node: %s (%s)",
        power_change, hostname, system_id)
    # Emit starting event.
    if power_change == 'on':
        event_type = EVENT_TYPES.NODE_POWER_ON_STARTING
    elif power_change == 'off':
        event_type = EVENT_TYPES.NODE_POWER_OFF_STARTING
    elif power_change == 'cycle':
        event_type = EVENT_TYPES.NODE_POWER_CYCLE_STARTING
    yield send_node_event(event_type, system_id, hostname)


@asynchronous
@deferred  # Always return a Deferred.
def maybe_change_power_state(
        system_id, hostname, power_type, power_change, context,
        clock=reactor):
    """Attempt to change the power state of a node.

    If there is no power action already in progress, register this
    action and then pass change_power_state() to the reactor to call
    later and then return.

    This function exists to guarantee that PowerActionAlreadyInProgress
    errors will be raised promptly, before any work is done to power the
    node on.

    :raises: PowerActionAlreadyInProgress if there's already a power
        action in progress for this node.
    """
    assert power_change in ('on', 'off', 'cycle'), (
        "Unknown power change: %s" % power_change)

    power_driver = PowerDriverRegistry.get_item(power_type)
    if power_driver is None:
        raise PowerActionFail(
            "Unknown power_type '%s'" % power_type)
    missing_packages = power_driver.detect_missing_packages()
    if len(missing_packages):
        raise PowerActionFail(
            "'%s' package(s) are not installed" % " ".join(
                missing_packages))

    # There should be one and only one power change for each system ID.
    if system_id in power_action_registry:
        current_power_change, d = power_action_registry[system_id]
    else:
        current_power_change, d = None, None

    if current_power_change is None:
        # Arrange for the power change to happen later; do not make the caller
        # wait, because it might take a long time. We set a timeout so that if
        # the power action doesn't return in a timely fashion (or fails
        # silently or some such) it doesn't block other actions on the node.
        d = deferLater(
            clock, 0, deferWithTimeout, CHANGE_POWER_STATE_TIMEOUT,
            change_power_state, system_id, hostname, power_type, power_change,
            context, clock)

        power_action_registry[system_id] = power_change, d

        # Whether we succeed or fail, we need to remove the action from the
        # registry of actions, otherwise subsequent actions will fail.
        d.addBoth(callOut, power_action_registry.pop, system_id, None)

        # Log cancellations distinctly from other errors.
        def eb_cancelled(failure):
            failure.trap(CancelledError)
            log.msg(
                "%s: Power could not be set to %s; timed out."
                % (hostname, power_change))
            return power_change_failure(
                system_id, hostname, power_change, "Timed out")
        d.addErrback(eb_cancelled)

        # Catch-all log.
        d.addErrback(
            log.err, "%s: Power %s failed." % (
                hostname, power_change))

        return d

    elif current_power_change == power_change:
        # What we want is already happening; let it continue.
        pass

    else:
        # Right now we reject conflicting power changes. However, we have the
        # Deferred (in `d`) along which the current power change is occurring,
        # so the option to cancel is available if we want it.
        raise PowerActionAlreadyInProgress(
            "Unable to change power state to '%s' for node %s: another "
            "action is already in progress for that node." %
            (power_change, hostname))


@asynchronous
@inlineCallbacks
def change_power_state(
        system_id, hostname, power_type, power_change, context,
        clock=reactor):
    """Change the power state of a node.

    This monitors the result of the power change by querying the power state
    of the node, thus attempting to ensure that the requested change has taken
    place.

    Success is reported using `power_change_success`. Power-related failures
    are reported using `power_change_failure`. Other failures must be reported
    by the caller.
    """
    yield power_change_starting(system_id, hostname, power_change)
    yield perform_power_driver_change(
        system_id, hostname, power_type, power_change, context)
    if power_type not in PowerDriverRegistry:
        returnValue(None)
    new_power_state = yield perform_power_driver_query(
        system_id, hostname, power_type, context)
    if new_power_state == "unknown" or new_power_state == power_change:
        yield power_change_success(system_id, hostname, power_change)
    elif new_power_state == 'on' and power_change == 'cycle':
        yield power_change_success(system_id, hostname, new_power_state)
    returnValue(new_power_state)


@asynchronous
def perform_power_driver_query(system_id, hostname, power_type, context):
    """Query the node's power state.

    No exception handling is performed here. This allows `get_power_state` to
    perform multiple queries and only log the final error.

    :param power_type: This must refer to one of the Python-based power
        drivers, and *not* to a template-based one.
    """
    # Get power driver for given power type
    power_driver = PowerDriverRegistry[power_type]
    return power_driver.query(system_id, context)


@asynchronous
@inlineCallbacks
def get_power_state(system_id, hostname, power_type, context, clock=reactor):
    """Return the power state of the given node.

    :return: The string "on", "off" or "unknown".
    :raises PowerActionFail: When there's a failure querying the node's
        power state.
    """
    def check_power_state(state):
        if state not in ("on", "off", "unknown"):
            # This is considered an error.
            raise PowerActionFail(state)

    # Capture errors as we go along.
    exc_info = None, None, None

    power_driver = PowerDriverRegistry.get_item(power_type)
    if power_driver is None:
        raise PowerActionFail(
            "Unknown power_type '%s'" % power_type)
    missing_packages = power_driver.detect_missing_packages()
    if len(missing_packages):
        raise PowerActionFail(
            "'%s' package(s) are not installed" % ", ".join(
                missing_packages))
    try:
        power_state = yield perform_power_driver_query(
            system_id, hostname, power_type, context)
        check_power_state(power_state)
    except:
        # Hold the error; it will be reported later.
        exc_info = sys.exc_info()
    else:
        returnValue(power_state)

    # Reaching here means that things have gone wrong.
    assert exc_info != (None, None, None)
    exc_type, exc_value, exc_trace = exc_info
    raise exc_type(exc_value).with_traceback(exc_trace)


@inlineCallbacks
def power_query_success(system_id, hostname, state):
    """Report a node that for which power querying has succeeded."""
    message = "Power state queried: %s" % state
    yield power_state_update(system_id, state)
    yield send_node_event(
        EVENT_TYPES.NODE_POWER_QUERIED_DEBUG,
        system_id, hostname, message)


@inlineCallbacks
def power_query_failure(system_id, hostname, failure):
    """Report a node that for which power querying has failed."""
    maaslog.error("%s: Power state could not be queried: %s" % (
        hostname, failure.getErrorMessage()))
    yield power_state_update(system_id, 'error')
    yield send_node_event(
        EVENT_TYPES.NODE_POWER_QUERY_FAILED,
        system_id, hostname, failure.getErrorMessage())


@asynchronous
def report_power_state(d, system_id, hostname):
    """Report the result of a power query.

    :param d: A `Deferred` that will fire with the node's updated power state,
        or an error condition. The callback/errback values are passed through
        unaltered. See `get_power_state` for details.
    """
    def cb(state):
        d = power_query_success(system_id, hostname, state)
        d.addCallback(lambda _: state)
        return d

    def eb(failure):
        d = power_query_failure(system_id, hostname, failure)
        d.addCallback(lambda _: failure)
        return d

    return d.addCallbacks(cb, eb)


def maaslog_report_success(node, power_state):
    """Log change in power state for node."""
    if node['power_state'] != power_state:
        maaslog.info(
            "%s: Power state has changed from %s to %s.", node['hostname'],
            node['power_state'], power_state)
    return power_state


def maaslog_report_failure(node, failure):
    """Log failure to query node."""
    if failure.check(PowerActionFail, PowerError):
        maaslog.error(
            "%s: Could not query power state: %s.",
            node['hostname'], failure.getErrorMessage())
    elif failure.check(NoSuchNode):
        maaslog.debug(
            "%s: Could not update power state: "
            "no such node.", node['hostname'])
    else:
        maaslog.error(
            "%s: Failed to refresh power state: %s",
            node['hostname'], failure.getErrorMessage())
        # XXX: newell 07-25-16 bug=1600264: Will re-instate
        # the traceback logging with python.twisted.log once
        # Debug is added for the rack controller.
        # # Also write out a full traceback to the server log.
        # log.err(failure, "Failed to refresh power state.")


def query_node(node, clock):
    """Calls `get_power_state` on the given node.

    Logs to maaslog as errors and power states change.
    """
    if node['system_id'] in power_action_registry:
        maaslog.debug(
            "%s: Skipping query power status, "
            "power action already in progress.",
            node['hostname'])
        return succeed(None)
    else:
        d = get_power_state(
            node['system_id'], node['hostname'], node['power_type'],
            node['context'], clock=clock)
        d = report_power_state(d, node['system_id'], node['hostname'])
        d.addCallbacks(
            partial(maaslog_report_success, node),
            partial(maaslog_report_failure, node))
        return d


def query_all_nodes(nodes, max_concurrency=5, clock=reactor):
    """Queries the given nodes for their power state.

    Nodes' states are reported back to the region.

    :return: A deferred, which fires once all nodes have been queried,
        successfully or not.
    """
    semaphore = DeferredSemaphore(tokens=max_concurrency)
    queries = (
        semaphore.run(query_node, node, clock)
        for node in nodes if node['power_type'] in PowerDriverRegistry)
    return DeferredList(queries, consumeErrors=True)