a

config.py

@@ -1,4 +1,24 @@
+import logging
+
 from decouple import config
 from etcd3_wrapper import Etcd3Wrapper
+from ucloud_common.vm import VmPool
+from ucloud_common.host import HostPool
+from ucloud_common.request import RequestPool
+
+logging.basicConfig(
+    level=logging.DEBUG,
+    filename="log.txt",
+    filemode="a",
+    format="%(asctime)s: %(levelname)s - %(message)s",
+    datefmt="%d-%b-%y %H:%M:%S",
+)
+
+vm_prefix = config("VM_PREFIX")
+host_prefix = config("HOST_PREFIX")
+request_prefix = config("REQUEST_PREFIX")
 
 etcd_client = Etcd3Wrapper(host=config("ETCD_URL"))
+vm_pool = VmPool(etcd_client, vm_prefix)
+host_pool = HostPool(etcd_client, host_prefix)
+request_pool = RequestPool(etcd_client, request_prefix)

main.py

@@ -1,105 +1,85 @@
 # TODO
 #  1. send an email to an email address defined by env['admin-email']
 #     if resources are finished
-#  2. v3) Introduce a status endpoint of the scheduler -
+#  2. Introduce a status endpoint of the scheduler -
 #     maybe expose a prometheus compatible output
 
-import argparse
 import logging
 
-from decouple import config
-
 from config import etcd_client as client
-
-from ucloud_common.vm import VmPool
-from ucloud_common.host import HostPool
-from ucloud_common.request import RequestEntry, RequestPool, RequestType
+from config import (host_pool, request_pool, vm_pool, request_prefix)
+from ucloud_common.request import RequestEntry, RequestType
 from helper import (get_suitable_host, dead_host_mitigation, dead_host_detection,
                     assign_host)
 
-logging.basicConfig(
-    level=logging.DEBUG,
-    filename="log.txt",
-    filemode="a",
-    format="%(asctime)s: %(levelname)s - %(message)s",
-    datefmt="%d-%b-%y %H:%M:%S",
-)
+pending_vms = []
 
 
-def main(vm_prefix, host_prefix, request_prefix):
-    logging.info(f"{'*' * 5} SESSION STARTED {'*' * 5}")
+def main():
+    global pending_vms
 
-    vm_pool = VmPool(client, vm_prefix)
-    host_pool = HostPool(client, host_prefix)
-    request_pool = RequestPool(client, request_prefix)
-
-    PENDING_VMS = []
-    for events_iterator in [
+    for request_iterator in [
         client.get_prefix(request_prefix, value_in_json=True),
         client.watch_prefix(request_prefix, timeout=5, value_in_json=True),
     ]:
-        for e in events_iterator:
-            if not e.value:
-                continue
-            e = RequestEntry(e)
-            logging.debug(f"{e.key}, {e.value}")
+        for request_event in request_iterator:
+            request_entry = RequestEntry(request_event)
+            logging.debug(f"{request_entry.key}, {request_entry.value}")
 
             # Never Run time critical mechanism inside timeout
             # mechanism because timeout mechanism only comes
             # when no other event is happening. It means under
-            # heavy load there would not be a timeout<
-            if e.type == "TIMEOUT":
+            # heavy load there would not be a timeout event.
+            if request_entry.type == "TIMEOUT":
+
+                # Detect hosts that are dead and set their status
+                # to "DEAD", and their VMs' status to "KILLED"
                 logging.debug("TIMEOUT event occured")
                 dead_hosts = dead_host_detection()
                 logging.debug(f"Dead hosts: {dead_hosts}")
                 dead_host_mitigation(dead_hosts)
-                #
-                # vm_scheduled = []
-                # for vm in PENDING_VMS:
-                #     if assign_host(vm) is not None:
-                #         vm_scheduled.append(vm)
-                #
-                # for vm in vm_scheduled:
-                #     PENDING_VMS.remove(vm)
-                # logging.debug(f"Remaining Pending: {PENDING_VMS}")
 
-            elif e.type == RequestType.ScheduleVM:
-                if hasattr(e, "migration") and e.migration and\
-                        hasattr(e, "destination") and e.destination:
-                    client.client.delete(e.key)
-                    vm = vm_pool.get(e.uuid)
-                    host = get_suitable_host(vm.specs, [host_pool.get(e.destination)])
+                # If there are VMs that weren't assigned a host
+                # because there wasn't a host available which
+                # meets requirement of that VM then we would
+                # create a new ScheduleVM request for that VM
+                # on our behalf.
+                while pending_vms:
+                    pending_vm_entry = pending_vms.pop()
+                    r = RequestEntry.from_scratch(type=f"ScheduleVM",
+                                                  uuid=pending_vm_entry.uuid,
+                                                  hostname=pending_vm_entry.hostname)
+                    request_pool.put(r)
+
+                logging.debug(f"Remaining Pending: {pending_vms}")
+
+            elif request_entry.type == RequestType.ScheduleVM:
+                vm_entry = vm_pool.get(request_entry.uuid)
+                client.client.delete(request_entry.key)  # consume Request
+
+                # If Request is about a VM which is labelled as "migration"
+                # and has a destination
+                if hasattr(request_entry, "migration") and request_entry.migration \
+                        and hasattr(request_entry, "destination") and request_entry.destination:
+                    host = get_suitable_host(vm_entry.specs, [host_pool.get(request_entry.destination)])
                     if host:
                         r = RequestEntry.from_scratch(type=RequestType.InitVMMigration,
-                                                      uuid=e.uuid, destination=e.destination)
+                                                      uuid=request_entry.uuid,
+                                                      destination=request_entry.destination)
                         request_pool.put(r)
-                        print(host, e)
                     else:
                         logging.info("Requested destination host doesn't have enough capacity"
-                                     f"to hold {vm.uuid}")
+                                     f"to hold {vm_entry.uuid}")
                 else:
-                    client.client.delete(e.key)
-                    vm = vm_pool.get(e.uuid)
-                    if assign_host(vm) is None:
-                        vm.log.append("Can't schedule VM. No Resource Left.")
-                        vm_pool.put(vm)
+                    # assign_host only returns None when we couldn't be able to assign
+                    # a host to a VM because of resource constraints
+                    if assign_host(vm_entry) is None:
+                        vm_entry.log.append("Can't schedule VM. No Resource Left.")
+                        vm_pool.put(vm_entry)
 
-                        PENDING_VMS.append(vm)
+                        pending_vms.append(vm_entry)
                         logging.info("No Resource Left. Emailing admin....")
-                        logging.debug(f"Pending VMS: {PENDING_VMS}")
 
 
-if __name__ == "__main__":
-    argparser = argparse.ArgumentParser()
-    argparser.add_argument(
-        "--vm_prefix", required=False, default=config("VM_PREFIX")
-    )
-    argparser.add_argument(
-        "--host_prefix", required=False, default=config("HOST_PREFIX")
-    )
-    argparser.add_argument(
-        "--request_prefix", required=False, default=config("REQUEST_PREFIX")
-    )
-    args = argparser.parse_args()
-
-    main(args.vm_prefix, args.host_prefix, args.request_prefix)
+logging.info(f"{'*' * 5} SESSION STARTED {'*' * 5}")
+main()