[conf] added unkown values

ucloud/scheduler/main.py.old

@@ -0,0 +1,93 @@
+# TODO
+#  1. send an email to an email address defined by env['admin-email']
+#     if resources are finished
+#  2. Introduce a status endpoint of the scheduler -
+#     maybe expose a prometheus compatible output
+
+from ucloud.common.request import RequestEntry, RequestType
+from ucloud.config import etcd_client
+from ucloud.config import host_pool, request_pool, vm_pool, env_vars
+from .helper import (get_suitable_host, dead_host_mitigation, dead_host_detection,
+                     assign_host, NoSuitableHostFound)
+from . import logger
+
+
+def main():
+    logger.info("%s SESSION STARTED %s", '*' * 5, '*' * 5)
+
+    pending_vms = []
+
+    for request_iterator in [
+        etcd_client.get_prefix(env_vars.get('REQUEST_PREFIX'), value_in_json=True),
+        etcd_client.watch_prefix(env_vars.get('REQUEST_PREFIX'), timeout=5, value_in_json=True),
+    ]:
+        for request_event in request_iterator:
+            request_entry = RequestEntry(request_event)
+            # 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 event.
+            if request_entry.type == "TIMEOUT":
+
+                # Detect hosts that are dead and set their status
+                # to "DEAD", and their VMs' status to "KILLED"
+                dead_hosts = dead_host_detection()
+                if dead_hosts:
+                    logger.debug("Dead hosts: %s", dead_hosts)
+                    dead_host_mitigation(dead_hosts)
+
+                # 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="ScheduleVM",
+                                                  uuid=pending_vm_entry.uuid,
+                                                  hostname=pending_vm_entry.hostname,
+                                                  request_prefix=env_vars.get("REQUEST_PREFIX"))
+                    request_pool.put(r)
+
+            elif request_entry.type == RequestType.ScheduleVM:
+                logger.debug("%s, %s", request_entry.key, request_entry.value)
+
+                vm_entry = vm_pool.get(request_entry.uuid)
+                if vm_entry is None:
+                    logger.info("Trying to act on {} but it is deleted".format(request_entry.uuid))
+                    continue
+                etcd_client.client.delete(request_entry.key)  # consume Request
+
+                # If the 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:
+                    try:
+                        get_suitable_host(vm_specs=vm_entry.specs,
+                                          hosts=[host_pool.get(request_entry.destination)])
+                    except NoSuitableHostFound:
+                        logger.info("Requested destination host doesn't have enough capacity"
+                                    "to hold %s" % vm_entry.uuid)
+                    else:
+                        r = RequestEntry.from_scratch(type=RequestType.InitVMMigration,
+                                                      uuid=request_entry.uuid,
+                                                      destination=request_entry.destination,
+                                                      request_prefix=env_vars.get("REQUEST_PREFIX"))
+                        request_pool.put(r)
+
+                # If the Request is about a VM that just want to get started/created
+                else:
+                    # assign_host only returns None when we couldn't be able to assign
+                    # a host to a VM because of resource constraints
+                    try:
+                        assign_host(vm_entry)
+                    except NoSuitableHostFound:
+                        vm_entry.add_log("Can't schedule VM. No Resource Left.")
+                        vm_pool.put(vm_entry)
+
+                        pending_vms.append(vm_entry)
+                        logger.info("No Resource Left. Emailing admin....")
+
+
+if __name__ == "__main__":
+    main()