Welcome to opie’s documentation!¶
opie is the materialization of the preemptible instances extension serving as a reference implementation. This package provides a set of pluggable extensions for OpenStack Compute (nova) making possible to execute premptible instances using a modified filter scheduler.
opie is completely pluggable, with the exception of a modification in the internal nova compute API that needs to be applied manually.
Contents:
Installation¶
opie depends on the OpenStack Compute (nova) version that you are using. Currently it is only tested with OpenStack Compute Liberty (version 12.0.X), so you need to ensure that you are running that specific version.
Installation via Ubuntu/Debian packages¶
Add the opie PPA to your system manually, by copying the linbes below and adding them to your system’s software sources:
deb http://ppa.launchpad.net/aloga/opie/ubuntu trusty main
deb-src http://ppa.launchpad.net/aloga/opie/ubuntu trusty main
Then, you can install it via apt-get:
apt-get update
apt-get install opie
Paching nova compute API¶
Unfortunately, even if opie is desinged to exploit nova’s modularity, there is a manual patch that needs to be applied. Execute the following command to save the patch:
cat > /tmp/nova-compute-api.patch << EOF
--- /a/compute/api.py 2016-07-27 13:50:06.625151062 +0200
+++ /b/compute/api.py 2016-09-13 12:40:36.190353525 +0200
@@ -886,7 +886,7 @@
access_ip_v4, access_ip_v6,
requested_networks, config_drive,
auto_disk_config, reservation_id,
- max_count):
+ max_count, preemptible):
"""Verify all the input parameters regardless of the provisioning
strategy being performed.
"""
@@ -948,6 +948,8 @@
instance_type, image_meta)
system_metadata = {}
+ if preemptible:
+ system_metadata["preemptible"] = True
# PCI requests come from two sources: instance flavor and
# requested_networks. The first call in below returns an
@@ -1144,7 +1146,7 @@
block_device_mapping, auto_disk_config,
reservation_id=None, scheduler_hints=None,
legacy_bdm=True, shutdown_terminate=False,
- check_server_group_quota=False):
+ check_server_group_quota=False, preemptible=False):
"""Verify all the input parameters regardless of the provisioning
strategy being performed and schedule the instance(s) for
creation.
@@ -1184,7 +1186,7 @@
key_name, key_data, security_groups, availability_zone,
forced_host, user_data, metadata, access_ip_v4,
access_ip_v6, requested_networks, config_drive,
- auto_disk_config, reservation_id, max_count)
+ auto_disk_config, reservation_id, max_count, preemptible)
# max_net_count is the maximum number of instances requested by the
# user adjusted for any network quota constraints, including
@@ -1553,7 +1555,8 @@
block_device_mapping=None, access_ip_v4=None,
access_ip_v6=None, requested_networks=None, config_drive=None,
auto_disk_config=None, scheduler_hints=None, legacy_bdm=True,
- shutdown_terminate=False, check_server_group_quota=False):
+ shutdown_terminate=False, check_server_group_quota=False,
+ preemptible=False):
"""Provision instances, sending instance information to the
scheduler. The scheduler will determine where the instance(s)
go and will handle creating the DB entries.
@@ -1584,7 +1587,8 @@
scheduler_hints=scheduler_hints,
legacy_bdm=legacy_bdm,
shutdown_terminate=shutdown_terminate,
- check_server_group_quota=check_server_group_quota)
+ check_server_group_quota=check_server_group_quota,
+ preemptible=preemptible)
def _check_auto_disk_config(self, instance=None, image=None,
**extra_instance_updates):
EOF
And apply the patch as follows:
Ubuntu/Debian:
cd /usr/lib/python2.7/dist-packages/nova patch -p1 < /tmp/nova-compute-api.patch
RedHat/CentOS:
cd /usr/lib/python2.7/site-packages/nova patch -p1 < /tmp/nova-compute-api.patch
Once this is done, ensure that you restart your nova-api service:
service nova-api restart
Configuration¶
Once opie is installed you should enable it in your nova.conf configuration
file.
opie implements a different host manager and scheduler, compatible with the
original FilterScheduler, so ensure that your configuration file contains the
following in the [DEFAULT] section:
[DEFAULT]
scheduler_driver = opie.scheduler.filter_scheduler.FilterScheduler
scheduler_host_manager = opie.scheduler.host_manager.HostManager
Moreover, in order to do a proper scheduling, opie implements two additional weighers:
PreemptibleDurationWeigher: This weigher assumes that you are charging your users on 1h periods, therefire it will assign weights based on 1h-period consumptions. This way, the machines with the largest remainder (that is, time above 1h-periods) will get the lowest weight. For instance, if machine A has 1h 59min it will get a weight lower than a machine with 1h 01min running time.PreemptibleCountWeigher: This will assign weights based on the number of preemptible instances that are running on a host.
You can enable both weighers and its multipliers by adding the following
configuration options to the [DEFAULT] section:
scheduler_weight_classes = (...), opie.scheduler.weights.preemptible.PreemptibleDurationWeigher, opie.scheduler.weights.preemptible.PreemptibleCountWeigher
preemptible_count_weight_multiplier = 1000.0
preemptible_duration_weight_multiplier = 1000.0
Once the scheduler is configured, ensure that you restart your
nova-scheduler service:
service nova-scheduler restart