Port VM on-node tasks to Celery worker system

Adds Celery versions of the flush_locks, device_attach, and
device_detach functions.

daemon-common/celery.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+
+# celery.py - PVC client function library, Celery helper fuctions
+# Part of the Parallel Virtual Cluster (PVC) system
+#
+#    Copyright (C) 2018-2023 Joshua M. Boniface <joshua@boniface.me>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, version 3.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+###############################################################################
+
+
+import sys
+
+from logging import getLogger
+from time import sleep
+
+
+class TaskFailure(Exception):
+    pass
+
+
+def start(celery, msg, current=1, total=2):
+    logger = getLogger(__name__)
+    logger.info(f"Starting: {msg}")
+    celery.update_state(
+        state="RUNNING", meta={"current": current, "total": total, "status": msg}
+    )
+    sleep(0.5)
+
+
+def fail(celery, msg, current=1, total=2):
+    logger = getLogger(__name__)
+    logger.error(msg)
+    sys.tracebacklimit = 0
+    raise TaskFailure(msg)
+
+
+def update(celery, msg, current=1, total=2):
+    logger = getLogger(__name__)
+    logger.info(f"Task update: {msg}")
+    celery.update_state(
+        state="RUNNING", meta={"current": current, "total": total, "status": msg}
+    )
+    sleep(0.5)
+
+
+def finish(celery, msg, current=2, total=2):
+    logger = getLogger(__name__)
+    celery.update_state(
+        state="RUNNING",
+        meta={"current": current, "total": total, "status": "Finishing up"},
+    )
+    sleep(0.25)
+    logger.info(f"Success: {msg}")
+    return {"status": msg, "current": current, "total": total}