This page describes how to set up the system to take advantage of Amazon’s EC2 spot instances.
Nodemanager should have configured cloud sizes that include the
preemptible boolean parameter. For example, for every on-demand cloud node size, you could create a
.spot variant, like this:
[Size m4.large] cores = 2 scratch = 32000 [Size m4.large.spot] cores = 2 instance_type = m4.large preemptible = true scratch = 32000
crunch-dispatch-slurm service needs a matching instance type configuration on
/etc/arvados/config.yml, following the previous example:
Clusters: uuid_prefix: InstanceTypes: - Name: m4.large VCPUs: 2 RAM: 7782000000 Scratch: 32000000000 Price: 0.1 - Name: m4.large.spot Preemptible: true VCPUs: 2 RAM: 7782000000 Scratch: 32000000000 Price: 0.1
InstanceType names should match those defined on nodemanager’s config file because it’s
crunch-dispatch-slurm’s job to select the instance type and communicate the decision to
nodemanager via Slurm.
Container requests will need the
preemptible scheduling parameter included, to make the dispatcher request a spot instance. The API Server configuration file includes an option that when active, will auto assign the
preemptible parameter to any new child container request if it doesn’t have it already. To activate this feature, the following should be added to the
With this configuration active, child container requests should include the
preemptible = false parameter at creation time to avoid being scheduled for spot instance usage.
When requesting spot instances, Amazon’s API may return an authorization error depending on how users and permissions are set on the account. If this is the case check nodemanager’s log for:
BaseHTTPError: AuthFailure.ServiceLinkedRoleCreationNotPermitted: The provided credentials do not have permission to create the service-linked role for EC2 Spot Instances.
The account needs to have a service linked role created. This can be done by logging into the AWS account, go to IAM Management → Roles and create the
AWSServiceRoleForEC2Spot role by clicking on the
Create button, selecting
EC2 service and
EC2 - Spot Instances use case.
Amazon’s Spot instances prices are declared at instance request time and defined by the maximum price that the user is willing to pay per hour. By default, this price is the same amount as the on-demand version of each instance type, and this setting is the one that nodemanager uses for now, as it doesn’t include any pricing data to the spot instance request.
The real price that a spot instance has at any point in time is discovered at the end of each usage hour, depending on instance demand. For this reason, AWS provides a data feed subscription to get hourly logs, as described on Amazon’s User Guide.
The content of this documentation is licensed under the
Commons Attribution-Share Alike 3.0 United States licence.
Code samples in this documentation are licensed under the Apache License, Version 2.0.