AWS Cost Explorer

What is AWS Cost Explorer?

AWS Cost Explorer is a visual, interactive tool in the AWS Billing console that helps you analyze, forecast, and manage your AWS costs and usage. It provides ready-made reports, customizable charts, and filters to explore spend by service, account, tag, and time period. Cost Explorer draws from the same underlying data as the Cost and Usage Reports (CUR) and can also be queried programmatically via the Cost Explorer API.

Key features

• Pre-built and custom reports: view costs by service, linked account, region, or usage type; save reports for repeated analysis.
• Forecasting: Cost Explorer projects future spend based on historical usage and trends.
• RI & Savings Plans reports: analyze Reserved Instance (RI) utilization/coverage and Savings Plan recommendations.
• Granular filtering: filter by tags, purchase option (On-Demand, Reserved, Savings Plan), API operations, and more.
• Programmatic access: use the Cost Explorer API or AWS SDKs (boto3) to retrieve cost and usage data.

Default reports and useful views

• Cost and usage (daily/monthly) — quick view of total spend and trends.
• Monthly costs by linked account — useful for consolidated billing and chargeback.
• Monthly costs by service — identify which AWS services drive most spend.
• EC2 running hours and usage breakdown — helps in rightsizing and instance optimization.
• RI utilization & coverage — shows how effectively Reserved Instances are used and where you may be under- or over-committed.

Common use-cases and examples

• Cost allocation and chargeback: tag resources (project, team, environment) and use Cost Explorer to report spend per tag for internal billing.
• Rightsizing: combine Cost Explorer usage reports with Cost Anomaly Detection and Trusted Advisor to identify underutilized instances and reduce waste.
• Forecasting and budget planning: use forecast data to set budgets and alert thresholds for future months.
• Savings Plan & RI analysis: compare on-demand spend with Savings Plans or RIs and run utilization/coverage reports before purchasing.
• Programmatic reporting: automate daily cost checks by calling the Cost Explorer API and pushing results to an internal dashboard or Slack channel.

Example: simple Cost Explorer API call (boto3)

import boto3
from datetime import datetime, timedelta

ce = boto3.client('ce')
end = datetime.today().replace(day=1)
start = (end - timedelta(days=90)).replace(day=1)

resp = ce.get_cost_and_usage(
  TimePeriod={'Start': start.strftime('%Y-%m-%d'), 'End': end.strftime('%Y-%m-%d')},
  Granularity='MONTHLY',
  Metrics=['UnblendedCost'],
  GroupBy=[{'Type': 'DIMENSION', 'Key': 'SERVICE'}]
)

for month in resp['ResultsByTime']:
  print(month['TimePeriod'], month['Groups'])

Best practices

• Tag consistently: enable cost allocation tags, enforce tagging via automation, and use tags in Cost Explorer filters.
• Use daily views for operational alerts and monthly/rolling-12 views for budgeting and forecasting.
• Combine Cost Explorer with AWS Budgets and Cost Anomaly Detection to receive alerts on unexpected spend.
• Review RI and Savings Plan reports regularly and adjust commitments based on utilization.
• Export detailed data to the Cost and Usage Report (CUR) and query it with Athena for ad-hoc deep analysis.

Pricing notes

• Viewing and interacting with Cost Explorer in the console is free.
• The Cost Explorer API has a small per-request charge (refer to the AWS pricing page for current rates).

Related Razorops articles

• AWS Budgets
• AWS Cost and Usage Reports (CUR) — deep dives
• AWS Trusted Advisor and Cost Optimization
• AWS Savings Plans vs Reserved Instances
• Top 50 AWS DevOps Interview Questions and Answers

Top 20 AWS Solutions Architect interview FAQs

1. Q: What is the difference between EC2 instance store and EBS? A: EBS is persistent, network-attached block storage that survives instance stops; instance store is ephemeral and data is lost if the instance stops or terminates.

2. Q: How does S3 achieve high durability? A: S3 stores multiple copies across Availability Zones, performs integrity checks, and offers 11 nines of durability for standard storage.

3. Q: What is a VPC and why use it? A: A VPC isolates network resources and provides control over subnets, routing, security groups, and connectivity (VPN/Direct Connect).

4. Q: Security groups vs NACLs — differences? A: Security groups are stateful and apply to instances; NACLs are stateless and apply to subnets.

5. Q: How do you design for high availability? A: Use multiple AZs, autoscaling, load balancers, managed services (RDS Multi-AZ), and data replication or cross-region backups.

6. Q: When to use SQS vs SNS? A: Use SQS for decoupled queue-based processing; use SNS for pub/sub notifications to multiple subscribers.

7. Q: What is cross-region replication (CRR) for S3? A: CRR asynchronously copies objects from one bucket to another in a different region for DR and compliance.

8. Q: How do you secure data in transit and at rest? A: Use TLS for transit; SSE-KMS, SSE-S3, or client-side encryption for data at rest; manage keys via KMS.

9. Q: What is an Auto Scaling group? A: ASG manages EC2 fleet capacity based on policies/metrics and replaces unhealthy instances automatically.

10. Q: How does Route 53 routing policy work (simple, weighted, latency)? A: Simple returns a single resource; weighted distributes traffic by weight; latency routes based on lowest latency.

11. Q: When to use RDS Multi-AZ vs Read Replica? A: Multi-AZ for HA and automatic failover; Read Replica for read scaling and reporting workloads.

12. Q: What is CloudFormation? A: Declarative IaC to provision AWS resources repeatedly and track drift.

13. Q: How do you optimize costs in AWS? A: Rightsize, use spot/reserved/savings plans, lifecycle policies, and monitor with Cost Explorer and Budgets.

14. Q: Explain S3 consistency model. A: S3 provides strong read-after-write consistency for PUTs and for overwrite/DELETE across all regions.

15. Q: IAM best practices? A: Least privilege, use roles and temporary credentials, enable MFA, rotate keys, and use centralized identity.

16. Q: How to design a data lake on AWS? A: Use S3 as central store, Glue Data Catalog for metadata, Lake Formation for access control, and Athena/EMR/SageMaker for processing.

17. Q: Differences between ALB and NLB? A: ALB is Layer 7 (HTTP/HTTPS) with routing features; NLB is Layer 4 for high-performance TCP/UDP with static IP support.

18. Q: What is a VPC endpoint and when to use it? A: VPC endpoints (Gateway/Interface) allow private connectivity to AWS services without needing internet access.

19. Q: How would you perform disaster recovery in AWS? A: Choose a DR strategy (Backup & Restore, Pilot Light, Warm Standby, Multi-Site) based on RTO/RPO and automate failover.

20. Q: How do you monitor and troubleshoot AWS infrastructure? A: Use CloudWatch metrics/logs, CloudTrail for API audits, X-Ray for tracing, VPC Flow Logs for network debugging, and third-party APMs.