aetherscale

commit 57a97efaa00b03312acd388f105b9d882e7a70f0
parent a847be3343a32e8886de2cae2e7f4c48282d08c0
Author: Stefan Koch <programming@stefan-koch.name>
Date:   Mon,  7 Dec 2020 22:17:52 +0100

implement graceful shutdown through qemu monitor

Diffstat:
M
aetherscale/client.py
 | 
14
+++++++++++++-
M
aetherscale/computing.py
 | 
28
++++++++++++++++++++++++----
A
aetherscale/qemu.py
 | 
28
++++++++++++++++++++++++++++

3 files changed, 65 insertions(+), 5 deletions(-)
diff --git a/aetherscale/client.py b/aetherscale/client.py
@@ -75,6 +75,9 @@ def main():
     stop_vm_parser = subparsers.add_parser('stop-vm')
     stop_vm_parser.add_argument(
         '--vm-id', dest='vm_id', help='ID of the VM to stop', required=True)
+    stop_vm_parser.add_argument(
+        '--kill', dest='kill', action='store_true', default=False,
+        help='Kill the VM immediately, no graceful shutdown')
     delete_vm_parser = subparsers.add_parser('delete-vm')
     delete_vm_parser.add_argument(
         '--vm-id', dest='vm_id', help='ID of the VM to delete', required=True)
@@ -95,7 +98,16 @@ def main():
                 'image': args.image,
             }
         }
-    elif args.subparser_name in ['start-vm', 'stop-vm', 'delete-vm']:
+    elif args.subparser_name == 'stop-vm':
+        response_expected = True
+        data = {
+            'command': args.subparser_name,
+            'options': {
+                'vm-id': args.vm_id,
+                'kill': args.kill,
+            }
+        }
+    elif args.subparser_name in ['start-vm', 'delete-vm']:
         response_expected = True
         data = {
             'command': args.subparser_name,
diff --git a/aetherscale/computing.py b/aetherscale/computing.py
@@ -16,6 +16,7 @@ from typing import List, Optional, Dict, Any, Callable
 
 from . import interfaces
 from . import execution
+from . import qemu
 
 # TODO: Since this is not a command line interface file anymore, switch to
 # logging from print
@@ -43,6 +44,10 @@ def user_image_path(vm_id: str) -> Path:
     return USER_IMAGE_FOLDER / f'{vm_id}.qcow2'
 
 
+def qemu_socket_monitor(vm_id: str) -> Path:
+    return Path(f'/tmp/aetherscale-qmp-{vm_id}.sock')
+
+
 def create_user_image(vm_id: str, image_name: str) -> Path:
     base_image = BASE_IMAGE_FOLDER / f'{image_name}.qcow2'
     if not base_image.is_file():
@@ -137,22 +142,31 @@ def stop_vm(options: Dict[str, Any]) -> Dict[str, str]:
     except KeyError:
         raise ValueError('VM ID not specified')
 
+    kill_flag = bool(options.get('kill', False))
+    stop_status = 'killed' if kill_flag else 'stopped'
+
     unit_name = systemd_unit_name_for_vm(vm_id)
 
     if not execution.systemd_unit_exists(unit_name):
         raise RuntimeError('VM does not exist')
     elif not execution.systemctl_is_running(unit_name):
         response = {
-            'status': 'killed',
+            'status': stop_status,
             'vm-id': vm_id,
             'hint': f'VM "{vm_id}" was not running',
         }
     else:
         execution.disable_systemd_unit(unit_name)
-        execution.stop_systemd_unit(unit_name)
+
+        if kill_flag:
+            execution.stop_systemd_unit(unit_name)
+        else:
+            qemu_socket = qemu_socket_monitor(vm_id)
+            qm = qemu.QemuMonitor(qemu_socket)
+            qm.execute('system_powerdown')
 
         response = {
-            'status': 'killed',
+            'status': stop_status,
             'vm-id': vm_id,
         }
 
@@ -165,6 +179,8 @@ def delete_vm(options: Dict[str, Any]) -> Dict[str, str]:
     except KeyError:
         raise ValueError('VM ID not specified')
 
+    # force kill stop when a VM is deleted
+    options['kill'] = True
     stop_vm(options)
 
     unit_name = systemd_unit_name_for_vm(vm_id)
@@ -209,10 +225,14 @@ def create_qemu_systemd_unit(
     name_quoted = shlex.quote(
         f'qemu-vm-{qemu_config.vm_id},process=vm-{qemu_config.vm_id}')
 
+    qemu_monitor_path = qemu_socket_monitor(qemu_config.vm_id)
+    socket_quoted = shlex.quote(f'unix:{qemu_monitor_path},server,nowait')
+
     command = f'qemu-system-x86_64 -m 4096 -accel kvm -hda {hda_quoted} ' \
         f'-device {device_quoted} -netdev {netdev_quoted} ' \
         f'-name {name_quoted} ' \
-        '-nographic'
+        '-nographic ' \
+        f'-qmp {socket_quoted}'
 
     with tempfile.NamedTemporaryFile(mode='w+t', delete=False) as f:
         f.write('[Unit]\n')
diff --git a/aetherscale/qemu.py b/aetherscale/qemu.py
@@ -0,0 +1,28 @@
+import json
+from pathlib import Path
+import socket
+from typing import Any
+
+
+class QemuMonitor:
+    def __init__(self, socket_file: Path):
+        # TODO: It's not really nice that we use the file object
+        # to read lines and the socket to write
+        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        self.sock.connect(str(socket_file))
+        self.f = self.sock.makefile('rw')
+
+        # Initialize connection immediately
+        self._initialize()
+
+    def execute(self, command: str) -> Any:
+        json_line = json.dumps({'execute': command}) + '\n'
+        self.sock.sendall(json_line.encode('utf-8'))
+        return json.loads(self.f.readline())
+
+    def _initialize(self):
+        # Read the capabilities
+        self.f.readline()
+
+        # Acknowledge the QMP capability negotiation
+        self.execute('qmp_capabilities')