uncloud-mravi/scheduler/helper.py

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import bitmath
from collections import Counter
from functools import reduce
from ucloud_common.vm import VmPool, VMStatus
from ucloud_common.host import HostPool, HostStatus
from ucloud_common.request import RequestEntry, RequestPool, RequestType
from decouple import config
from config import etcd_client as client
vm_pool = VmPool(client, config("VM_PREFIX"))
host_pool = HostPool(client, config("HOST_PREFIX"))
request_pool = RequestPool(client, config("REQUEST_PREFIX"))
def accumulated_specs(vms_specs):
if not vms_specs:
return {}
return reduce((lambda x, y: Counter(x) + Counter(y)), vms_specs)
def remaining_resources(host_specs, vms_specs):
# Return remaining resources host_specs - vms
_vms_specs = Counter(vms_specs)
_remaining = Counter(host_specs)
for component in _vms_specs:
if isinstance(_vms_specs[component], str):
_vms_specs[component] = int(bitmath.parse_string(_vms_specs[component]).to_MB())
elif isinstance(_vms_specs[component], list):
_vms_specs[component] = map(lambda x: int(bitmath.parse_string(x).to_MB()), _vms_specs[component])
_vms_specs[component] = reduce(lambda x, y: x + y, _vms_specs[component], 0)
for component in _remaining:
if isinstance(_remaining[component], str):
_remaining[component] = int(bitmath.parse_string(_remaining[component]).to_MB())
elif isinstance(_remaining[component], list):
_remaining[component] = map(lambda x: int(bitmath.parse_string(x).to_MB()), _remaining[component])
_remaining[component] = reduce(lambda x, y: x + y, _remaining[component], 0)
_remaining.subtract(_vms_specs)
return _remaining
class NoSuitableHostFound(Exception):
"""Exception when no host found that can host a VM."""
def get_suitable_host(vm_specs, hosts=None):
if hosts is None:
hosts = host_pool.by_status(HostStatus.alive)
for host in hosts:
# Filter them by host_name
vms = vm_pool.by_host(host.key)
# Filter them by status
vms = vm_pool.by_status(VMStatus.running, vms)
running_vms_specs = [vm.specs for vm in vms]
# Accumulate all of their combined specs
running_vms_accumulated_specs = accumulated_specs(running_vms_specs)
# Find out remaining resources after
# host_specs - already running vm_specs
remaining = remaining_resources(host.specs, running_vms_accumulated_specs)
# Find out remaining - new_vm_specs
remaining = remaining_resources(remaining, vm_specs)
if all(map(lambda x: x >= 0, remaining.values())):
return host.key
raise NoSuitableHostFound
def dead_host_detection():
# Bring out your dead! - Monty Python and the Holy Grail
hosts = host_pool.by_status(HostStatus.alive)
dead_hosts_keys = []
for host in hosts:
# Only check those who claims to be alive
if host.status == HostStatus.alive:
if not host.is_alive():
dead_hosts_keys.append(host.key)
return dead_hosts_keys
def dead_host_mitigation(dead_hosts_keys):
for host_key in dead_hosts_keys:
host = host_pool.get(host_key)
host.declare_dead()
vms_hosted_on_dead_host = vm_pool.by_host(host_key)
for vm in vms_hosted_on_dead_host:
vm.declare_killed()
vm_pool.put(vm)
host_pool.put(host)
def assign_host(vm):
vm.hostname = get_suitable_host(vm.specs)
vm_pool.put(vm)
r = RequestEntry.from_scratch(type=RequestType.StartVM,
uuid=vm.uuid,
hostname=vm.hostname)
request_pool.put(r)
vm.log.append("VM scheduled for starting")
return vm.hostname