.AWS community-days 2020: Cost Optimization

Sep 28th 2020-6 min read
Marc Schröter
Marc SchröterCEO

A lecture for SRE, DevOps and FinOps teams on controlling AWS costs with optimizations and practical tips from practice.

Since the presentation is in german, here are the key topics written down in this blogpost

Here is the video link 📹

Download the PowerPoint here: AWS Community Days 2020 - cost-optimisation

AWS Lambda

There are mainly 3 factors that make up your Lambda costs: the number of executions, the duration of each execution and the memory allocated to the function.

It is a good incentive to write efficient code in order to shorten the duration of each execution and therefore pay less for your Lambda. By automating, monitoring and eventually getting professional expertise you're already on a good path to FinDev.

Read more about Cutting down the cost on your Lambda.

Useful tool: AWS Lambda Power Tuning

Blog Content

AWS Kubernetes

4 Techniques to save money on EC2 for EKS

Auto-scaling, right sizing, down-scaling and optimizing instance price by replacing on-demand with spot instances are your best friends here.

Cluster Autoscaler

A requirement for cost-optimization in a Kubernetes cluster is having a Cluster Autoscaler running, it monitors the cluster for pods that are unable to run and detects nodes that have been underutilized.

Horizontal Pod Autoscaler (HPA)

After having a Cluster Autoscaler running you can be sure of the instance-hours being in line with the requirements of the pods in the cluster.

With the Horizontal Pod Autoscaler you are able to scale out or in the number of pods based on specific metrics, optimize pod hours and further optimize instance-hours but in order for it to work you have to ensure that the Kubernetes metrics server is deployed.

The combination of Cluster Autoscaler and Horizontal Pod Autoscaler is an effective way to keep EC2 Instance-hours tied as close as possible to actual utilization of the workloads running in the cluster.

Example HPA Configuration:

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
    name: nginx-ingress-controller
        apiVersion: apps/v1
        kind: Deployment
        name: nginx-ingress-controller
    minReplicas: 1
    maxreplicas: 5
    targetCPUUtilizationPercentage: 80

Right Size your Pods

Set the resources allocated for the containers in your pods. Requests should align as close as possible to the actual utilization. If the value is too low containers may throttle resources, if it's too high you're having unused resourced which you still pay for. "Slack costs" are described as when the actual utilization which is lower than the requested value.

Useful tool: Kube-resource-report

Down Scaling

Scale in and out the deployments based on time of day with the kube-downscaler in your cluster

A default uptime can configured via an environment variable

  • DEFAULT_UPTIME = Mon-Fri 05:00-19:00 America/LosAngeles
  • All deployments will have the size set to 0
  • For all times outside of 5:00 AM - 7:00 PM, Monday - Friday

Individual namespaces and deployments can override their uptime

  • Set a different update with the downscaler/uptime annotation
  • Or disable it altogether with downscaler/exclude

Purchase options

Spot Instances have a significantly lower cost, for example a m5.large instance is consistently 50-60% less expensive than using On-Demand.

Run a Termination Handler tool, e.g.

Determine the termination workflow by...

  • Identifying that a Spot Instance is about to be interrupted in two minutes
  • Using the two-minute notification window to gracefully prepare the node for termination
  • Tainting the node and cordoning it off to prevent new pods from being placed on it
  • Draining connections on the running pods

AWS SageMaker


Sagemaker offers various instance families. Each family is optimized for a different application which means they have to be analyzed to fit your usecase but remember that not all instance types are suitable for inference jobs.

AWS Elastic Inference

Another option to lower GPU instance- and inference cost is utilizing Elastic Inference which can achieve you up to 75% of cost-saving and is available for EC2 and SageMaker Notebook & Endpoints. The downside of this is a 10-15% slower performance.

Automatically scaling endpoints

With the automatic scaling for SageMaker you can add capacity or accelerated instances to your endpoints automatically when needed instead of monitoring the inference volume manually and changing endpoint configurations as a reaction to this. The endpoint adjusts the needed instances automatically to the actual workload.

Stop idle on-demand notebook instances

Certain SageMaker resources, for example instances for processing-training, tuning and batch-transformation are ephemeral, meaning SageMaker will start them automatically and stop them when the job is done.

Other resources, for example build-computing or hosting endpoints, are not ephemeral and the user has control over when to start or stop those resources. This knowledge of how unused resources can be identified or stopped can lead to a better cost-optimizati