Totally revamped ucloud-vm

.gitignore

@@ -3,3 +3,6 @@
 __pycache__/
 venv/
 .env
+
+log.txt
+vm_socklog/

etcd3_wrapper

@@ -1 +1 @@
-Subproject commit cb2a416a17d6789e613ba3b9957917770f4211e1
+Subproject commit 615a0709186e74ee5c9ae78f385fd0c4c4b3834d

main.py

@@ -1,127 +1,247 @@
 # TODO
-#  1. Verify that commands successfully did what they are
-#     supposed to do by querying state of VM using QMP.
-#  2. Implement Monitoring of VM.
-
 
 # For QEMU Monitor Protocol Commands Information, See
 # https://qemu.weilnetz.de/doc/qemu-doc.html#pcsys_005fmonitor
 
 import json
-import shutil
-import os
-import subprocess
 import argparse
 import qmp
+import logging
+import os
+import shutil
 
 from etcd3_wrapper import Etcd3Wrapper
+from dataclasses import dataclass
+from typing import Union
+from functools import wraps
 from decouple import config
 
+running_vms = []
+client = Etcd3Wrapper()
 
-def get_vm_start_cmd(owner_dir, vm_uuid, vm=False):
-    vm_sock_flags = f"-qmp unix:{owner_dir}/.vm/{vm_uuid}-sock,server,nowait"
-    vm_start_command_flags = (
-        f"-boot c -net nic -net user -m 256 {vm_sock_flags} -daemonize"
-    )
-    vm_start_command = f"""qemu-system-x86_64 {owner_dir}/.vm/{vm_uuid}.raw {vm_start_command_flags}"""
+
+@dataclass
+class VM:
+    key: str
+    vm: qmp.QEMUMachine
+
+
+logging.basicConfig(
+    level=logging.DEBUG,
+    filename="log.txt",
+    filemode="a",
+    format="%(asctime)s: %(levelname)s - %(message)s",
+    datefmt="%d-%b-%y %H:%M:%S",
+)
+
+
+def need_running_vm(func):
+    @wraps(func)
+    def wrapper(e):
+        vm = get_vm(running_vms, e.key)
         if vm:
-        vm_start_command += " -display none"
-    return vm_start_command
-
-
-def get_qemu_mon(sock_file):
-    m = qmp.QEMUMonitorProtocol(sock_file)
             try:
-        m.connect()
-    except FileNotFoundError as _:
-        return None
-    return m
+                status = vm.vm.command("query-status")
+                logging.debug(f"VM Status Check - {status}")
+            except OSError:
+                logging.info(f"{func.__name__} failed - VM {e.key} - Unknown Error")
+
+            return func(e)
+        else:
+            logging.info(f"{func.__name__} failed because VM {e.key} is not running")
+            return
+    return wrapper
 
 
-def main(hostname, is_vm):
-    client = Etcd3Wrapper()
-
-    events = client.watch_prefix("/v1/vm/")
-
-    # events = client.get_prefix("/v1/vm/")
-    for e in events:
-        e.value = json.loads(e.value)
-        e_hostname = e.value["hostname"]
-        e_status = e.value["status"]
-        vm_uuid = e.key.split("/")[-1]
-        owner_dir = f"/var/www/{e.value['owner']}"
-
-        # If it is not for me then skip it
-        if e_hostname != hostname:
-            continue
-        print(e_status, e)
-
-        if e_status == "SCHEDULED_DEPLOY":
+def create_vm(owner_dir, vm_uuid, e):
     image = client.get(
         f"/v1/image/{e.value['image_uuid']}", value_in_json=True
     )
     if image:
+        logging.debug(image)
         image_uuid = e.value["image_uuid"]
-                print(image)
-                print("Creating New VM...")
+
+        logging.info("Creating New VM...")
 
         os.makedirs(f"{owner_dir}/.vm", exist_ok=True)
 
         if not os.path.isfile(f"{owner_dir}/.vm/{vm_uuid}.raw"):
             shutil.copy(
-                        f"/var/vm/{image_uuid}.raw",
-                        f"{owner_dir}/.vm/{vm_uuid}.raw",
+                f"/var/vm/{image_uuid}.raw", f"{owner_dir}/.vm/{vm_uuid}.raw"
             )
 
         e.value["status"] = "REQUESTED_START"
     client.put(e.key, json.dumps(e.value))
 
-        elif e_status == "REQUESTED_SUSPEND":
-            m = get_qemu_mon(f"{owner_dir}/.vm/{vm_uuid}-sock")
 
-            if m:
-                print("Suspending")
-                m.command("stop")
-                m.close()
+def start_vm(vm_path, e):
+    if not os.path.isfile(vm_path):
+        logging.info(f"Image file of vm {e.key} does not exists")
+        logging.info(f"Setting vm {e.key} status to DELETED")
+        e.value["status"] = "DELETED"
+        client.put(e.key, json.dumps(e.value))
+        return
+
+    _vm = get_vm(running_vms, e.key)
+    if _vm:
+        logging.info(f"{e.key} already running")
+        e.value["status"] = "RUNNING"
+        client.put(e.key, json.dumps(e.value))
+        return
+
+    vm = qmp.QEMUMachine(
+        "/usr/bin/qemu-system-x86_64",
+        test_dir="vm_socklog",
+        args=[
+            vm_path,
+            "-boot",
+            "c",
+            "-net",
+            "nic",
+            "-net",
+            "user",
+            "-m",
+            "1024",
+            "-vnc",
+            f":{len(running_vms)}",
+        ],
+    )
+    try:
+        logging.info(f"Starting {e.key}")
+        vm.launch()
+        if vm.is_running():
+            running_vms.append(VM(e.key, vm))
+            e.value["status"] = "RUNNING"
+            client.put(e.key, e.value, value_in_json=True)
+        else:
+            e.value["status"] = "KILLED"
+            client.put(e.key, e.value, value_in_json=True)
+            return
+    except (qmp.QEMUMachineError, TypeError):
+        logging.info(f"Machine Error Occurred on {e.key}")
+        e.value["status"] = "KILLED"
+        client.put(e.key, e.value, value_in_json=True)
+    else:
+        logging.info(f"Started Successfully {e.key}")
+
+
+@need_running_vm
+def suspend_vm(e):
+    vm = get_vm(running_vms, e.key)
+    vm.vm.command("stop")
+    if vm.vm.command("query-status")["status"] == "paused":
         e.value["status"] = "SUSPENDED"
         client.put(e.key, json.dumps(e.value))
+        logging.info(f"Successfully suspended VM {e.key}")
     else:
-                print("VM Not Running")
+        logging.info(f"Suspending VM {e.key} failed")
+
+
+@need_running_vm
+def resume_vm(e):
+    vm = get_vm(running_vms, e.key)
+    vm.vm.command("cont")
+    if vm.vm.command("query-status")["status"] == "running":
+        e.value["status"] = "RUNNING"
+        client.put(e.key, json.dumps(e.value))
+        logging.info(f"Successfully resumed VM {e.key}")
+    else:
+        logging.info(f"Resuming VM {e.key} failed")
+
+
+@need_running_vm
+def shutdown_vm(e):
+    vm = get_vm(running_vms, e.key)
+    vm.vm.shutdown()
+    if not vm.vm.is_running():
+        logging.info(f"VM {e.key} shutdown successfully")
+        e.value["status"] = "STOPPED"
+        client.put(e.key, json.dumps(e.value))
+        running_vms.remove(vm)
+
+
+def delete_vm(e):
+    logging.info(f"Deleting VM {e.key}")
+    shutdown_vm(e)
+    vm = client.get(e.key, value_in_json=True)
+    if vm:
+        vm_id = e.key.split('/')[-1]
+        vm_owner = e.value['owner']
+        vm_path = f"{config('BASE_DIR')}/{vm_owner}/.vm/{vm_id}"
+
+        if os.path.exists(vm_path):
+            os.remove(vm_path)
+        client.client.delete(e.key)
+        logging.info(f"VM {vm.key} deleted")
+    else:
+        logging.info(f"Cannot delete key {e.key} because it doesn't exists")
+
+
+def get_vm(vm_list: list, vm_key) -> Union[VM, None]:
+    return next((vm for vm in vm_list if vm.key == vm_key), None)
+
+
+def main(hostname):
+    events = client.watch_prefix("/v1/vm/", timeout=10)
+
+    # events = client.get_prefix("/v1/vm/")
+    for e in events:
+        try:
+            e.value = json.loads(e.value)
+        except json.JSONDecodeError:
+            logging.error(f"Invalid JSON {e.value}")
+            continue
+
+        e_status = e.value["status"]
+
+        if e_status == "TIMEOUT":
+            logging.info("Timeout")
+            _vms = filter(lambda v: v.value["hostname"] == hostname, client.get_prefix("/v1/vm", value_in_json=True))
+            alleged_running_vms = filter(lambda v: v.value["status"] == "RUNNING", _vms)
+            for vm in alleged_running_vms:
+                _vm = get_vm(running_vms, vm.key)
+                if (_vm and not _vm.vm.is_running()) or _vm is None:
+                    logging.debug(f"{_vm} {vm.key}")
+                    logging.info(f"{vm.key} is not running but is said to be running")
+                    logging.info(f"Updating {vm.key} status to KILLED")
+                    vm.value["status"] = "KILLED"
+                    client.put(vm.key, json.dumps(vm.value))
+            continue
+
+        e_hostname = e.value["hostname"]
+        vm_uuid = e.key.split("/")[-1]
+        owner_dir = f"{config('BASE_DIR')}/{e.value['owner']}"
+
+        # If it is not for me then skip it
+        if e_hostname != hostname:
+            continue
+
+        logging.debug(f"EVENT: {e}")
+
+        if e_status == "SCHEDULED_DEPLOY":
+            create_vm(owner_dir, vm_uuid, e)
+
+        elif e_status == "REQUESTED_SUSPEND":
+            suspend_vm(e)
 
         elif e_status == "REQUESTED_RESUME":
-            m = get_qemu_mon(f"{owner_dir}/.vm/{vm_uuid}-sock")
-            if m:
-                print("Resuming")
-
-                m.command("cont")
-                m.close()
-
-                e.value["status"] = "RESUMED"
-                client.put(e.key, json.dumps(e.value))
-            else:
-                print("VM Not Running")
+            resume_vm(e)
 
         elif e_status == "REQUESTED_START":
-            m = get_qemu_mon(f"{owner_dir}/.vm/{vm_uuid}-sock")
-            if m:
-                m.close()
-                print("VM already running")
-                e.value["status"] = "RUNNING"
-                client.put(e.key, e.value, value_in_json=True)
-            else:
-                print("Starting VM")
-                subprocess.run(
-                    get_vm_start_cmd(owner_dir, vm_uuid, is_vm).split(" ")
-                )
-                e.value["status"] = "RUNNING"
-                client.put(e.key, e.value, value_in_json=True)
-        else:
-            continue
+            vm_path = f"{owner_dir}/.vm/{vm_uuid}.raw"
+            start_vm(vm_path, e)
+
+        elif e_status == "REQUESTED_SHUTDOWN":
+            shutdown_vm(e)
+
+        elif e_status == "DELETED":
+            delete_vm(e)
+
+        logging.info(f"Running VMs {running_vms}")
 
 
 argparser = argparse.ArgumentParser()
 argparser.add_argument("hostname", help="Name of this host. e.g /v1/host/1")
-argparser.add_argument("--vm", type=bool, default=False)
 args = argparser.parse_args()
 
-main(args.hostname, args.vm)
+main(args.hostname)

qmp/__init__.py

@@ -0,0 +1,535 @@
+# QEMU library
+#
+# Copyright (C) 2015-2016 Red Hat Inc.
+# Copyright (C) 2012 IBM Corp.
+#
+# Authors:
+#  Fam Zheng <famz@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+#
+# Based on qmp.py.
+#
+
+import errno
+import logging
+import os
+import subprocess
+import re
+import shutil
+import socket
+import tempfile
+
+from . import qmp
+
+
+LOG = logging.getLogger(__name__)
+
+# Mapping host architecture to any additional architectures it can
+# support which often includes its 32 bit cousin.
+ADDITIONAL_ARCHES = {
+    "x86_64" : "i386",
+    "aarch64" : "armhf"
+}
+
+def kvm_available(target_arch=None):
+    host_arch = os.uname()[4]
+    if target_arch and target_arch != host_arch:
+        if target_arch != ADDITIONAL_ARCHES.get(host_arch):
+            return False
+    return os.access("/dev/kvm", os.R_OK | os.W_OK)
+
+
+class QEMUMachineError(Exception):
+    """
+    Exception called when an error in QEMUMachine happens.
+    """
+
+
+class QEMUMachineAddDeviceError(QEMUMachineError):
+    """
+    Exception raised when a request to add a device can not be fulfilled
+
+    The failures are caused by limitations, lack of information or conflicting
+    requests on the QEMUMachine methods.  This exception does not represent
+    failures reported by the QEMU binary itself.
+    """
+
+class MonitorResponseError(qmp.QMPError):
+    """
+    Represents erroneous QMP monitor reply
+    """
+    def __init__(self, reply):
+        try:
+            desc = reply["error"]["desc"]
+        except KeyError:
+            desc = reply
+        super(MonitorResponseError, self).__init__(desc)
+        self.reply = reply
+
+
+class QEMUMachine(object):
+    """
+    A QEMU VM
+
+    Use this object as a context manager to ensure the QEMU process terminates::
+
+        with VM(binary) as vm:
+            ...
+        # vm is guaranteed to be shut down here
+    """
+
+    def __init__(self, binary, args=None, wrapper=None, name=None,
+                 test_dir="/var/tmp", monitor_address=None,
+                 socket_scm_helper=None):
+        '''
+        Initialize a QEMUMachine
+
+        @param binary: path to the qemu binary
+        @param args: list of extra arguments
+        @param wrapper: list of arguments used as prefix to qemu binary
+        @param name: prefix for socket and log file names (default: qemu-PID)
+        @param test_dir: where to create socket and log file
+        @param monitor_address: address for QMP monitor
+        @param socket_scm_helper: helper program, required for send_fd_scm()
+        @note: Qemu process is not started until launch() is used.
+        '''
+        if args is None:
+            args = []
+        if wrapper is None:
+            wrapper = []
+        if name is None:
+            name = "qemu-%d" % os.getpid()
+        self._name = name
+        self._monitor_address = monitor_address
+        self._vm_monitor = None
+        self._qemu_log_path = None
+        self._qemu_log_file = None
+        self._popen = None
+        self._binary = binary
+        self._args = list(args)     # Force copy args in case we modify them
+        self._wrapper = wrapper
+        self._events = []
+        self._iolog = None
+        self._socket_scm_helper = socket_scm_helper
+        self._qmp = None
+        self._qemu_full_args = None
+        self._test_dir = test_dir
+        self._temp_dir = None
+        self._launched = False
+        self._machine = None
+        self._console_set = False
+        self._console_device_type = None
+        self._console_address = None
+        self._console_socket = None
+
+        # just in case logging wasn't configured by the main script:
+        logging.basicConfig(level=logging.DEBUG)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.shutdown()
+        return False
+
+    # This can be used to add an unused monitor instance.
+    def add_monitor_null(self):
+        self._args.append('-monitor')
+        self._args.append('null')
+
+    def add_fd(self, fd, fdset, opaque, opts=''):
+        """
+        Pass a file descriptor to the VM
+        """
+        options = ['fd=%d' % fd,
+                   'set=%d' % fdset,
+                   'opaque=%s' % opaque]
+        if opts:
+            options.append(opts)
+
+        # This did not exist before 3.4, but since then it is
+        # mandatory for our purpose
+        if hasattr(os, 'set_inheritable'):
+            os.set_inheritable(fd, True)
+
+        self._args.append('-add-fd')
+        self._args.append(','.join(options))
+        return self
+
+    # Exactly one of fd and file_path must be given.
+    # (If it is file_path, the helper will open that file and pass its
+    # own fd)
+    def send_fd_scm(self, fd=None, file_path=None):
+        # In iotest.py, the qmp should always use unix socket.
+        assert self._qmp.is_scm_available()
+        if self._socket_scm_helper is None:
+            raise QEMUMachineError("No path to socket_scm_helper set")
+        if not os.path.exists(self._socket_scm_helper):
+            raise QEMUMachineError("%s does not exist" %
+                                   self._socket_scm_helper)
+
+        # This did not exist before 3.4, but since then it is
+        # mandatory for our purpose
+        if hasattr(os, 'set_inheritable'):
+            os.set_inheritable(self._qmp.get_sock_fd(), True)
+            if fd is not None:
+                os.set_inheritable(fd, True)
+
+        fd_param = ["%s" % self._socket_scm_helper,
+                    "%d" % self._qmp.get_sock_fd()]
+
+        if file_path is not None:
+            assert fd is None
+            fd_param.append(file_path)
+        else:
+            assert fd is not None
+            fd_param.append(str(fd))
+
+        devnull = open(os.path.devnull, 'rb')
+        proc = subprocess.Popen(fd_param, stdin=devnull, stdout=subprocess.PIPE,
+                                stderr=subprocess.STDOUT, close_fds=False)
+        output = proc.communicate()[0]
+        if output:
+            LOG.debug(output)
+
+        return proc.returncode
+
+    @staticmethod
+    def _remove_if_exists(path):
+        """
+        Remove file object at path if it exists
+        """
+        try:
+            os.remove(path)
+        except OSError as exception:
+            if exception.errno == errno.ENOENT:
+                return
+            raise
+
+    def is_running(self):
+        return self._popen is not None and self._popen.poll() is None
+
+    def exitcode(self):
+        if self._popen is None:
+            return None
+        return self._popen.poll()
+
+    def get_pid(self):
+        if not self.is_running():
+            return None
+        return self._popen.pid
+
+    def _load_io_log(self):
+        if self._qemu_log_path is not None:
+            with open(self._qemu_log_path, "r") as iolog:
+                self._iolog = iolog.read()
+
+    def _base_args(self):
+        if isinstance(self._monitor_address, tuple):
+            moncdev = "socket,id=mon,host=%s,port=%s" % (
+                self._monitor_address[0],
+                self._monitor_address[1])
+        else:
+            moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
+        args = ['-chardev', moncdev,
+                '-mon', 'chardev=mon,mode=control',
+                '-display', 'none', '-vga', 'none']
+        if self._machine is not None:
+            args.extend(['-machine', self._machine])
+        if self._console_set:
+            self._console_address = os.path.join(self._temp_dir,
+                                                 self._name + "-console.sock")
+            chardev = ('socket,id=console,path=%s,server,nowait' %
+                       self._console_address)
+            args.extend(['-chardev', chardev])
+            if self._console_device_type is None:
+                args.extend(['-serial', 'chardev:console'])
+            else:
+                device = '%s,chardev=console' % self._console_device_type
+                args.extend(['-device', device])
+        return args
+
+    def _pre_launch(self):
+        self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
+        if self._monitor_address is not None:
+            self._vm_monitor = self._monitor_address
+        else:
+            self._vm_monitor = os.path.join(self._temp_dir,
+                                            self._name + "-monitor.sock")
+        self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
+        self._qemu_log_file = open(self._qemu_log_path, 'wb')
+
+        self._qmp = qmp.QEMUMonitorProtocol(self._vm_monitor,
+                                            server=True)
+
+    def _post_launch(self):
+        self._qmp.accept()
+
+    def _post_shutdown(self):
+        if self._qemu_log_file is not None:
+            self._qemu_log_file.close()
+            self._qemu_log_file = None
+
+        self._qemu_log_path = None
+
+        if self._console_socket is not None:
+            self._console_socket.close()
+            self._console_socket = None
+
+        if self._temp_dir is not None:
+            shutil.rmtree(self._temp_dir)
+            self._temp_dir = None
+
+    def launch(self):
+        """
+        Launch the VM and make sure we cleanup and expose the
+        command line/output in case of exception
+        """
+
+        if self._launched:
+            raise QEMUMachineError('VM already launched')
+
+        self._iolog = None
+        self._qemu_full_args = None
+        try:
+            self._launch()
+            self._launched = True
+        except:
+            self.shutdown()
+
+            LOG.debug('Error launching VM')
+            if self._qemu_full_args:
+                LOG.debug('Command: %r', ' '.join(self._qemu_full_args))
+            if self._iolog:
+                LOG.debug('Output: %r', self._iolog)
+            raise
+
+    def _launch(self):
+        """
+        Launch the VM and establish a QMP connection
+        """
+        devnull = open(os.path.devnull, 'rb')
+        self._pre_launch()
+        self._qemu_full_args = (self._wrapper + [self._binary] +
+                                self._base_args() + self._args)
+        LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
+        self._popen = subprocess.Popen(self._qemu_full_args,
+                                       stdin=devnull,
+                                       stdout=self._qemu_log_file,
+                                       stderr=subprocess.STDOUT,
+                                       shell=False,
+                                       close_fds=False)
+        self._post_launch()
+
+    def wait(self):
+        """
+        Wait for the VM to power off
+        """
+        self._popen.wait()
+        self._qmp.close()
+        self._load_io_log()
+        self._post_shutdown()
+
+    def shutdown(self):
+        """
+        Terminate the VM and clean up
+        """
+        if self.is_running():
+            try:
+                self._qmp.cmd('quit')
+                self._qmp.close()
+            except:
+                self._popen.kill()
+            self._popen.wait()
+
+        self._load_io_log()
+        self._post_shutdown()
+
+        exitcode = self.exitcode()
+        if exitcode is not None and exitcode < 0:
+            msg = 'qemu received signal %i: %s'
+            if self._qemu_full_args:
+                command = ' '.join(self._qemu_full_args)
+            else:
+                command = ''
+            LOG.warn(msg, -exitcode, command)
+
+        self._launched = False
+
+    def qmp(self, cmd, conv_keys=True, **args):
+        """
+        Invoke a QMP command and return the response dict
+        """
+        qmp_args = dict()
+        for key, value in args.items():
+            if conv_keys:
+                qmp_args[key.replace('_', '-')] = value
+            else:
+                qmp_args[key] = value
+
+        return self._qmp.cmd(cmd, args=qmp_args)
+
+    def command(self, cmd, conv_keys=True, **args):
+        """
+        Invoke a QMP command.
+        On success return the response dict.
+        On failure raise an exception.
+        """
+        reply = self.qmp(cmd, conv_keys, **args)
+        if reply is None:
+            raise qmp.QMPError("Monitor is closed")
+        if "error" in reply:
+            raise MonitorResponseError(reply)
+        return reply["return"]
+
+    def get_qmp_event(self, wait=False):
+        """
+        Poll for one queued QMP events and return it
+        """
+        if len(self._events) > 0:
+            return self._events.pop(0)
+        return self._qmp.pull_event(wait=wait)
+
+    def get_qmp_events(self, wait=False):
+        """
+        Poll for queued QMP events and return a list of dicts
+        """
+        events = self._qmp.get_events(wait=wait)
+        events.extend(self._events)
+        del self._events[:]
+        self._qmp.clear_events()
+        return events
+
+    @staticmethod
+    def event_match(event, match=None):
+        """
+        Check if an event matches optional match criteria.
+
+        The match criteria takes the form of a matching subdict. The event is
+        checked to be a superset of the subdict, recursively, with matching
+        values whenever the subdict values are not None.
+
+        This has a limitation that you cannot explicitly check for None values.
+
+        Examples, with the subdict queries on the left:
+         - None matches any object.
+         - {"foo": None} matches {"foo": {"bar": 1}}
+         - {"foo": None} matches {"foo": 5}
+         - {"foo": {"abc": None}} does not match {"foo": {"bar": 1}}
+         - {"foo": {"rab": 2}} matches {"foo": {"bar": 1, "rab": 2}}
+        """
+        if match is None:
+            return True
+
+        try:
+            for key in match:
+                if key in event:
+                    if not QEMUMachine.event_match(event[key], match[key]):
+                        return False
+                else:
+                    return False
+            return True
+        except TypeError:
+            # either match or event wasn't iterable (not a dict)
+            return match == event
+
+    def event_wait(self, name, timeout=60.0, match=None):
+        """
+        event_wait waits for and returns a named event from QMP with a timeout.
+
+        name: The event to wait for.
+        timeout: QEMUMonitorProtocol.pull_event timeout parameter.
+        match: Optional match criteria. See event_match for details.
+        """
+        return self.events_wait([(name, match)], timeout)
+
+    def events_wait(self, events, timeout=60.0):
+        """
+        events_wait waits for and returns a named event from QMP with a timeout.
+
+        events: a sequence of (name, match_criteria) tuples.
+                The match criteria are optional and may be None.
+                See event_match for details.
+        timeout: QEMUMonitorProtocol.pull_event timeout parameter.
+        """
+        def _match(event):
+            for name, match in events:
+                if (event['event'] == name and
+                    self.event_match(event, match)):
+                    return True
+            return False
+
+        # Search cached events
+        for event in self._events:
+            if _match(event):
+                self._events.remove(event)
+                return event
+
+        # Poll for new events
+        while True:
+            event = self._qmp.pull_event(wait=timeout)
+            if _match(event):
+                return event
+            self._events.append(event)
+
+        return None
+
+    def get_log(self):
+        """
+        After self.shutdown or failed qemu execution, this returns the output
+        of the qemu process.
+        """
+        return self._iolog
+
+    def add_args(self, *args):
+        """
+        Adds to the list of extra arguments to be given to the QEMU binary
+        """
+        self._args.extend(args)
+
+    def set_machine(self, machine_type):
+        """
+        Sets the machine type
+
+        If set, the machine type will be added to the base arguments
+        of the resulting QEMU command line.
+        """
+        self._machine = machine_type
+
+    def set_console(self, device_type=None):
+        """
+        Sets the device type for a console device
+
+        If set, the console device and a backing character device will
+        be added to the base arguments of the resulting QEMU command
+        line.
+
+        This is a convenience method that will either use the provided
+        device type, or default to a "-serial chardev:console" command
+        line argument.
+
+        The actual setting of command line arguments will be be done at
+        machine launch time, as it depends on the temporary directory
+        to be created.
+
+        @param device_type: the device type, such as "isa-serial".  If
+                            None is given (the default value) a "-serial
+                            chardev:console" command line argument will
+                            be used instead, resorting to the machine's
+                            default device type.
+        """
+        self._console_set = True
+        self._console_device_type = device_type
+
+    @property
+    def console_socket(self):
+        """
+        Returns a socket connected to the console
+        """
+        if self._console_socket is None:
+            self._console_socket = socket.socket(socket.AF_UNIX,
+                                                 socket.SOCK_STREAM)
+            self._console_socket.connect(self._console_address)
+        return self._console_socket