4.2 KiB
Using spot instances
Spot instances usually cost around 30-70% less than an on-demand instance. So using them for your EKS workloads can save a lot of money but requires some special considerations as they will be terminated with only 2 minutes warning.
You need to install a daemonset to catch the 2 minute warning before termination. This will ensure the node is gracefully drained before termination. You can install the k8s-spot-termination-handler for this. There's a Helm chart:
helm install stable/k8s-spot-termination-handler --namespace kube-system
In the following examples at least 1 worker group that uses on-demand instances is included. This worker group has an added node label that can be used in scheduling. This could be used to schedule any workload but is important for the cluster-autoscaler as it might be end up unscheduled when spot instances are terminated. You can add this to the values of the cluster-autoscaler helm chart:
nodeSelector:
spot: "false"
Notes:
- The
spot_priceis set to the on-demand price so that the spot instances will run as long as they are the cheaper. - It's best to have a broad range of instance types to ensure there's always some instances to run when prices fluctuate.
- Using an AWS Spot Fleet is the best option but is not supported by this module yet.
- There is an AWS blog article about this here.
- Consider using k8s-spot-rescheduler to move pods from on-demand to spot instances.
Using Launch Configuration
Example Terraform worker group configuration that use an ASG with launch configuration:
worker_group_count = 3
worker_groups = [
{
name = "on-demand-1"
instance_type = "m4.xlarge"
asg_max_size = 1
autoscaling_enabled = true
kubelet_extra_args = "--node-labels=spot=false"
suspended_processes = "AZRebalance"
},
{
name = "spot-1"
spot_price = "0.39"
instance_type = "c4.2xlarge"
asg_max_size = 20
autoscaling_enabled = true
kubelet_extra_args = "--node-labels=spot=true"
suspended_processes = "AZRebalance"
},
{
name = "spot-2"
spot_price = "0.40"
instance_type = "m4.2xlarge"
asg_max_size = 20
autoscaling_enabled = true
kubelet_extra_args = "--node-labels=spot=true"
suspended_processes = "AZRebalance"
}
]
Using Launch Templates
Launch Template support is a recent addition to both AWS and this module. It might not be as tried and tested.
Example Terraform worker group configuration that use an ASG with a launch template:
worker_group_count = 1
worker_groups = [
{
name = "on-demand-1"
instance_type = "m4.xlarge"
asg_max_size = 10
autoscaling_enabled = true
kubelet_extra_args = "--node-labels=spot=false"
suspended_processes = "AZRebalance"
}
]
worker_group_launch_template_count = 1
worker_groups_launch_template = [
{
name = "spot-1"
instance_type = "m5.xlarge"
override_instance_type = "m4.xlarge"
spot_instance_pools = 2
on_demand_percentage_above_base_capacity = 0
spot_max_price = "0.384"
asg_max_size = 10
autoscaling_enabled = true
kubelet_extra_args = "--node-labels=spot=true"
}
]