Amazon ECS · Finder + guided fix
EC2 Retype ECS Manually
RetypeECS Manually
Right-size EC2 instances in ECS clusters by optimizing Auto Scaling Group configurations. CloudFix analyzes ECS resource usage for instance type changes.
What happens, in order.
Finder · read-only
Finds the opportunity
Scans your connected accounts with a read-only role. It can see resource metadata and usage; it can’t change anything.
You
Review in Recommendations
It appears in your Recommendations view with what it would save.
Guided fix
You make the change
You apply it yourself, following the fix’s step-by-step instructions; the write-up below explains it.
Finder role
Read-only. It can see resource metadata and usage. It can’t change anything.
Fixer role
Not used here: this one is a guided fix, so the change is yours to make.
Saves by
EC2 instances behind Amazon ECS clusters are often a poor fit for their containers' CPU and memory needs, so the whole cluster pays for capacity it doesn't use. CloudFix finds Auto Scaling Groups where a different instance family would cost less, and you update the group to the recommended type.
Optimize the cost and performance of your Amazon ECS clusters running on EC2 instances by rightsizing the underlying EC2 instances within their Auto Scaling Groups (ASGs). CloudFix looks at how the instances managed by an ECS Capacity Provider are actually used and identifies opportunities to change the instance type for the entire ASG to better match workload requirements, potentially recommending memory-optimized or compute-optimized instance families.
Manual Fix Required
CloudFix identifies the rightsizing opportunity but requires manual action to implement the change. Modifying the instance type in an Auto Scaling Group’s launch configuration or launch template affects all future instances launched by the ASG and often requires careful planning to manage instance replacement and potential downtime. Users must manually update the ASG configuration.
Overview
Problem Statement
EC2 instances backing ECS clusters are often configured with a single instance type within an Auto Scaling Group managed by a Capacity Provider. If the chosen instance type is not well-matched to the actual resource needs (CPU vs. Memory) of the containerized workloads, it can lead to inefficient resource utilization and unnecessary costs across the entire cluster.
Solution Identification
CloudFix uses your cost and usage data and the instances' own utilization to spot Auto Scaling Groups where switching the entire group to a different instance family (for example, from general-purpose to memory-optimized or compute-optimized) would be more cost-efficient at On-Demand prices.
AWS Services Affected
How CloudFix Identifies the Opportunity
CloudFix uses your cost and usage data and the utilization of the instances behind each ECS Capacity Provider to find Auto Scaling Groups whose instance family is a poor fit for the workload. Finding is read-only. The opportunity appears in your Recommendations with the current instance type, a suggested type and the estimated On-Demand savings, and you decide whether and when to make the change.
Manual Fix Steps
After CloudFix identifies an ECS EC2 retyping opportunity:
- Review Recommendation: Examine the identified ASG, the current instance type, the recommended instance type, and the supporting utilization data provided by CloudFix.
- Validate Recommendation: Assess if the recommended instance type aligns with your application’s performance needs. Consider peak loads, specific task requirements, and potential impacts of changing instance families (e.g., network performance, storage options).
- Update ASG Configuration: Modify the Launch Configuration or Launch Template associated with the Auto Scaling Group. Change the instance type to the recommended type.
- Implement Instance Refresh/Replacement: Changing the ASG configuration only affects *new* instances. To apply the change to existing instances, you need to either:
- Use EC2 Auto Scaling Instance Refresh to perform a rolling replacement of old instances with new ones based on the updated configuration.
- Manually terminate old instances (allowing the ASG to launch replacements with the new type) in a controlled manner, potentially using ECS container instance draining to gracefully stop tasks first.
- Monitor Cluster: After the instances have been replaced, monitor ECS service performance, task placement, and CloudWatch metrics for the new instances to ensure the cluster operates as expected.
FAQ
Q: Why is this a manual fix?
A: Modifying an ASG’s instance type and replacing the running instances is an operational change that can impact cluster capacity and potentially cause downtime if not managed carefully. User intervention is required for planning and execution.
Q: Does this finder recommend changing instance *size* (e.g., m5.large to m5.xlarge)?
A: This specific finder focuses on changing the instance *family* or *type* (e.g., m5.large to r5.large) to better match the workload, not necessarily changing the size. Other rightsizing finders might recommend size changes.
Q: What happens if I use Spot instances in my ASG?
A: Spot instances are outside the scope of this finder, and it does not recommend switching On-Demand capacity to Spot.
Q: Is downtime required?
A: Yes, replacing the EC2 instances within the ASG typically requires terminating old instances and launching new ones. While instance refresh and instance draining can minimize disruption, careful planning is needed to avoid impacting service availability.
Related Resources
- Amazon ECS Developer Guide
- Amazon EC2 Auto Scaling User Guide
- ECS Cluster Capacity Providers
- EC2 Auto Scaling Instance Refresh
- AWS Compute Optimizer
- ECS EC2 Manual Retyping (CloudFix Support)
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