AWS Commitments: How Cast AI Maximizes Reserved Instances and Savings Plans

AWS commitments like EC2 Reserved Instances and Savings Plans can significantly reduce your cloud costs, but only if you fully utilize them. Cast AI helps you maximize the benefits of your commitments by automatically syncing, tracking, and applying them while optimizing clusters.

This guide walks you through the process of uploading, managing, and monitoring your AWS commitments in Cast, ensuring they seamlessly integrate into your cost optimization workflow and deliver maximum savings with minimal effort.

How Cast helps users manage AWS commitments: Step-by-step guide

Step 1: Upload your AWS commitments

Cast supports the following types of AWS commitments: 

• EC2 Reserved Instances, 
• EC2 Savings Plans, 
• Compute Savings Plans.

Note: Cast also supports Resource-based Committed Use Discounts in the Google Cloud Platform and Azure Reserved Instances

The first step in using commitments is to upload them. Currently, you can choose from two approaches:

Connect your cloud account

The recommended method for uploading commitments is through the Connect cloud feature, which can be found on the Cast AI console homepage. When launched from the AWS Management Account, it automatically syncs commitments across all associated child accounts. This approach also unlocks extra capabilities, such as identifying active instances and clusters within your environment. 

Critically, it also enables Cast to understand how commitments are utilized by all cloud assets, except those that have been onboarded to the console. This results in more accurate commitment utilization reporting and prevents Cast from over-utilizing a commitment.

Upload commitments only

Another option is to only upload your commitments.

You can enable integrations on two levels:

• The preferred option is the organizational level, where scripts are run from the AWS Management Account, and the integration syncs data from the entire AWS organization. This approach provides visibility across all accounts. 
• The second option is account-scoped integration, which syncs assets and commitments from a single AWS account. This is done by running the script from an account that’s not the AWS Management Account.

Once either of the integrations is enabled, commitments will begin to appear on the commitments page. The data refreshes every hour, which means outdated commitments are removed and new ones are added.

Step 2: Manage your commitments

To start managing commitments, navigate to the Commitments page and select the Reserved Instances or Savings Plans tab.

Reserved Instances

Savings Plans 

Here’s what you can manage for a single commitment:

From both, you can do the following:

• Enable or disable commitments – Note that enabling or disabling commitments only impacts autoscaling decisions. By default, once commitments are uploaded, their utilization is automatically tracked, provided certain criteria are met (the commitment must still be active, and if specified, the region and instance type must match the nodes).
• Assign commitment to a cluster – Prioritized utilization is used to determine which cluster receives commitments first during autoscaling decisions. This ensures that the most suitable clusters are matched with available commitments based on predefined priorities.
• Track EC2 instance usage outside of Cast – If you enable the integration via connecting to your cloud account, Cast will be able to track utilization of all your commitments and only use what’s available for Cast. You can also achieve this by using the scope commitment slider shown in the image above.

Step 3: See commitments in the node list

When commitments are uploaded, their impact becomes visible in the cluster’s node list, where you can see how they influence resource allocation and autoscaling behavior.

Commitments are applied to a node in the following order: EC2 Reserved Instances, then EC2 Savings Plans, and finally Compute Savings Plans. This sequence is based on the level of specificity; more specific commitments typically offer greater discounts. A single node can also be partially covered by multiple commitments; for example, it might be 50% covered by a Reserved Instance and 50% by a Savings Plan.

Step 4: Using commitments in cluster rebalancing

Rebalancing is a process where Cast replaces suboptimal nodes with new ones and automatically shifts workloads to them, helping clusters reach an optimal state more efficiently.

Here’s how commitments are used during rebalancing:

1. Create a full rebalancing plan

2. Check commitments your rebalancing plan covers

3. After the rebalancing plan is complete, you can refer to the node list again:

You can also refer back to the commitments page to see that the ri-commitment is now fully utilized:

Step 5: Check the impact of commitments on Cost Monitoring

We can also analyze the commitment discounted nodes in the Cost Monitoring part of the console:

Wrap up

Once your commitments are uploaded and integrated, Cast takes care of the rest: automatically syncing, tracking, and applying them to optimize your infrastructure costs. From the initial upload to ongoing management, every step is designed to give you full visibility and control while minimizing manual effort.

With commitments visible in your node list, actively influencing autoscaling, and reflected in Cost Monitoring, you gain a clear, real-time view of how your Reserved Instances and Savings Plans are driving savings. Combined with rebalancing, this ensures your clusters always operate at peak efficiency: maximizing coverage, minimizing waste, and delivering the lowest possible cloud spend.