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confluent/confluent_server/aiohmi/cmd/virshbmc.py
T
Markus Hilger a53351a730 Give the virsh console loop a reason to wake
virEventRunDefaultImpl waits for an event that an idle domain need not
produce, so the thread could outlive a deactivation that reported success, and
every later activation was refused while it did. Registering a timeout is what
makes it return: measured, a thread with nothing registered was still running
four seconds after being asked to stop, and with a half second timer it came
out at once.
2026-08-10 14:36:37 +02:00

206 lines
7.7 KiB
Python
Executable File

# 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.
"""This is a simple, but working proof of concept of using aiohmi.ipmi.bmc to
control a VM
"""
import argparse
import asyncio
import sys
import threading
import libvirt
import aiohmi.ipmi.bmc as bmc
def lifecycle_callback(connection, domain, event, detail, console):
console.state = console.domain.state(0)
def error_handler(unused, error):
if (error[0] == libvirt.VIR_ERR_RPC
and error[1] == libvirt.VIR_FROM_STREAMS):
return
def stream_callback(stream, events, console):
try:
data = console.stream.recv(1024)
except Exception:
return
if console.sol and console.asyncloop:
# libvirt calls this from its own event thread, and asyncio objects
# are not thread safe, so hand the send to the loop that owns them.
asyncio.run_coroutine_threadsafe(console.sol.send_data(data),
console.asyncloop)
class LibvirtBmc(bmc.Bmc):
"""A class to provide an IPMI interface to the VirtualBox APIs."""
def __init__(self, authdata, hypervisor, domain, port):
super(LibvirtBmc, self).__init__(authdata, port)
# Rely on libvirt to throw on bad data
self.conn = libvirt.open(hypervisor)
self.name = domain
self.domain = self.conn.lookupByName(domain)
self.state = self.domain.state(0)
self.stream = None
self.asyncloop = None
self.run_console = False
self.conn.domainEventRegister(lifecycle_callback, self)
self.sol_thread = None
def cold_reset(self):
# Reset of the BMC, not managed system, here we will exit the demo
print('shutting down in response to BMC cold reset request')
sys.exit(0)
def get_power_state(self):
if self.domain.isActive():
return 'on'
else:
return 'off'
def power_off(self):
if not self.domain.isActive():
return 0xd5 # Not valid in this state
self.domain.destroy()
def power_on(self):
if self.domain.isActive():
return 0xd5 # Not valid in this state
self.domain.create()
def power_reset(self):
if not self.domain.isActive():
return 0xd5 # Not valid in this state
self.domain.reset()
def power_shutdown(self):
if not self.domain.isActive():
return 0xd5 # Not valid in this state
self.domain.shutdown()
def is_active(self):
return self.domain.isActive()
def check_console(self):
if (self.state[0] == libvirt.VIR_DOMAIN_RUNNING
or self.state[0] == libvirt.VIR_DOMAIN_PAUSED):
if self.stream is None:
self.stream = self.conn.newStream(libvirt.VIR_STREAM_NONBLOCK)
self.domain.openConsole(None, self.stream, 0)
self.stream.eventAddCallback(libvirt.VIR_STREAM_EVENT_READABLE,
stream_callback, self)
else:
if self.stream:
self.stream.eventRemoveCallback()
self.stream = None
return self.run_console
async def activate_payload(self, request, session):
# captured for stream_callback, which runs on a libvirt thread
self.asyncloop = asyncio.get_running_loop()
if self.sol_thread is not None and self.sol_thread.is_alive():
# The thread from the previous console has not come back out of
# virEventRunDefaultImpl. A second one would run a second event
# loop against the same stream, and setting run_console below
# would revive the first one when it finally wakes.
return await session.send_ipmi_response(code=0x80)
self.sol_thread = None
wasactive = self.activated
await super(LibvirtBmc, self).activate_payload(request, session)
if wasactive or not self.activated:
# the base handler refused: no io handler, or the domain is not
# running, so activated stayed false; or a console was already up,
# in which case activated was true before we asked and the thread
# for it is already running. Either way there is nothing to start.
return
self.run_console = True
self.sol_thread = threading.Thread(target=self.loop)
# virEventRunDefaultImpl can wait for an event that never comes, so
# this thread has no reliable end of its own
self.sol_thread.daemon = True
self.sol_thread.start()
async def deactivate_payload(self, request, session):
if self.activated and self.sol_thread:
self.run_console = False
# The thread only notices that after virEventRunDefaultImpl
# returns, which is documented as possibly never. Waiting on the
# event loop would stall every other session, so wait off it, and
# briefly: this is only to clear the state promptly in the normal
# case. A thread that outlives the wait stays owned here, and
# activate_payload refuses to start another until it is gone.
await asyncio.get_running_loop().run_in_executor(
None, self.sol_thread.join, 1)
if not self.sol_thread.is_alive():
self.sol_thread = None
await super(LibvirtBmc, self).deactivate_payload(request, session)
async def iohandler(self, data):
if self.stream:
self.stream.send(data)
def loop(self):
# virEventRunDefaultImpl waits for an event, and an idle domain can go
# a long time without producing one. Give it a reason to return, or
# the loop never reconsiders check_console and the thread cannot be
# stopped at all: measured as never waking without this, and returning
# at once with it.
timer = libvirt.virEventAddTimeout(500, lambda *args: None, None)
try:
while self.check_console():
libvirt.virEventRunDefaultImpl()
finally:
if timer >= 0:
libvirt.virEventRemoveTimeout(timer)
def main():
parser = argparse.ArgumentParser(
prog='virshbmc',
description='Pretend to be a BMC and proxy to virsh',
formatter_class=argparse.ArgumentDefaultsHelpFormatter
)
parser.add_argument('--port',
dest='port',
type=int,
default=623,
help='(UDP) port to listen on')
parser.add_argument('--connect',
dest='hypervisor',
default='qemu:///system',
help='The hypervisor to connect to')
parser.add_argument('--domain',
dest='domain',
required=True,
help='The name of the domain to manage')
args = parser.parse_args()
libvirt.virEventRegisterDefaultImpl()
libvirt.registerErrorHandler(error_handler, None)
mybmc = LibvirtBmc({'admin': 'password'},
hypervisor=args.hypervisor,
domain=args.domain,
port=args.port)
asyncio.run(mybmc.listen())
if __name__ == '__main__':
sys.exit(main())