AWS Billing And Cost Management

Cost Optimization Hub

Cost Optimization Hub (COH) is the recommended starting point for finding savings. It consolidates and de-duplicates recommendations from multiple sources (Compute Optimizer, Cost Explorer rightsizing, Savings Plans, Reserved Instances, idle resources) into a single prioritized view with estimated savings.

Why Start Here

• De-duplication: A single EC2 instance may appear in Compute Optimizer (right-size), Cost Explorer (RI recommendation), AND idle resource detection. COH consolidates these into one recommendation with the highest-impact action.

• Prioritization: Recommendations ranked by estimated monthly savings across all services and recommendation types.

• Aggregation: Single API to get all optimization opportunities across the account or organization.

CLI Commands

# List recommendation summaries grouped by resource type
aws cost-optimization-hub list-recommendation-summaries \
  --group-by ResourceType

# List recommendations sorted by savings (highest first)
aws cost-optimization-hub list-recommendations \
  --order-by '{"dimension":"EstimatedMonthlySavings","order":"Desc"}' \
  --max-results 20

# Get details for a specific recommendation
aws cost-optimization-hub get-recommendation \
  --recommendation-id <id>

# Filter by resource type
aws cost-optimization-hub list-recommendations \
  --filter '{"resourceTypes":["Ec2Instance"]}'

boto3 / call_boto3 Syntax

Parameter values and inner key names are the same for CLI and boto3 (top-level parameter names differ — CLI uses kebab-case like --order-by, boto3 uses camelCase like orderBy):

# List recommendation summaries
# groupBy valid values: AccountId, Region, ActionType, ResourceType,
#   RestartNeeded, RollbackPossible, ImplementationEffort
client.list_recommendation_summaries(groupBy='ResourceType')

# List recommendations sorted by savings
# orderBy.dimension: EstimatedMonthlySavings, EstimatedSavingsPercentage
# orderBy.order: Asc, Desc (case-sensitive — "DESC" will fail)
client.list_recommendations(
    orderBy={'dimension': 'EstimatedMonthlySavings', 'order': 'Desc'},
    maxResults=20
)

# Filter by resource type
client.list_recommendations(
    filter={'resourceTypes': ['Ec2Instance']},
    maxResults=20
)

# Get details for a specific recommendation
client.get_recommendation(recommendationId='<id>')

Common mistakes agents make with COH:

• Using RecommendationType as groupBy (not a valid value — use ResourceType or ActionType)

• Using CostReduction as orderBy dimension (not valid — use EstimatedMonthlySavings)

• Using DESC/ASC instead of Desc/Asc (case-sensitive)

• Calling non-existent operations like get_savings_summary or describe_recommendations

Recommendation Types

Filtering and Action Types

Action types (valid values for filter.actionTypes): Rightsize, Stop, Upgrade, PurchaseSavingsPlans, PurchaseReservedInstances, MigrateToGraviton, Delete, ScaleIn

Implementation effort levels (valid values for filter.implementationEfforts): VeryLow, Low, Medium, High, VeryHigh

Resource types (valid values for filter.resourceTypes): Ec2Instance, Ec2AutoScalingGroup, EbsVolume, LambdaFunction, EcsService, RdsDbInstance, RdsDbInstanceStorage, ComputeSavingsPlans, Ec2InstanceSavingsPlans, SageMakerSavingsPlans, Ec2ReservedInstances, RdsReservedInstances, OpenSearchReservedInstances, RedshiftReservedNodes, ElastiCacheReservedNodes, MemoryDbReservedInstances, DynamoDbReservedCapacity, AuroraDbClusterStorage, NatGateway

Idle vs Overprovisioned — Do NOT Confuse

Idle resources = near-zero utilization, safe to stop/delete. Action types: Stop, Delete. Overprovisioned resources = actively used but larger than needed, should be rightsized. Action type: Rightsize.

When a user asks "what idle resources can I terminate?" — only include Stop and Delete action types. Do NOT include Rightsize recommendations — those resources are still in use.

Compute Optimizer Detailed Operations

For deeper per-resource analysis beyond COH summaries, use Compute Optimizer directly:

# Check enrollment first
client.get_enrollment_status()

# Per-resource-type operations (service: compute-optimizer)
client.get_ec2_instance_recommendations(instanceArns=[...], filters=[...])
client.get_auto_scaling_group_recommendations(autoScalingGroupArns=[...])
client.get_ebs_volume_recommendations(volumeArns=[...])
client.get_lambda_function_recommendations(functionArns=[...])
client.get_rds_database_recommendations(resourceArns=[...])
client.get_ecs_service_recommendations(serviceArns=[...])

# Filters accept finding types: Underprovisioned, Overprovisioned, Optimized, NotOptimized
# Recommendation preferences: cpuVendorArchitectures=['AWS_ARM64'] for Graviton, ['CURRENT'] for same arch

De-duplication of Savings Estimates

COH de-duplicates savings across overlapping recommendation types. A single EC2 instance may have recommendations for rightsizing, Savings Plans, Reserved Instances, AND Graviton migration — but implementing one changes the savings from the others.

• list_recommendation_summaries returns per-group estimatedMonthlySavings that are NOT de-duped — summing them will overcount.

• The same response includes estimatedTotalDedupedSavings at the top level — this IS the de-duped total. Always use this field for total savings.

• list_recommendations returns per-recommendation estimatedMonthlySavings that are also NOT de-duped across recommendations for the same resource.

NEVER sum individual recommendation savings to get a total. Use estimatedTotalDedupedSavings from list_recommendation_summaries instead.

Workflow

1. Start with COH to get the prioritized, de-duplicated list of all savings opportunities

2. For deeper analysis on a specific recommendation, use the source service directly:

   • EC2 rightsizing details → references/ec2-rightsizing.md

   • SP purchase analysis → references/savings-plans.md

   • Lambda memory optimization → references/lambda-optimization.md

3. Calculate savings using a script (see references/deterministic-calculations.md) — NEVER sum savings estimates manually

Gotchas

• COH requires opt-in: aws cost-optimization-hub update-enrollment-status --status Active

• COH is available in us-east-1 only

• Recommendations refresh approximately every 24 hours

• Savings estimates use On-Demand pricing by default — may overstate savings if customer already has SPs/RIs

• COH does NOT include per-service optimizations (S3 lifecycle, CloudWatch log retention, NAT Gateway endpoints) — see references/service-optimization.md for those