AWS Cost Guard
Automated Billing Alerts & Daily Recaps
A robust cloud cost management solution built with Infrastructure as Code (IaC) to proactively monitor and report AWS expenditure.
Key AWS Services
Lambda
SNS
Budgets
CloudWatch Events
IAM
Cost Explorer
Python 3.9
Project Goal
This project automates cloud cost management on AWS. It provides proactive notifications for potential overspending and daily expenditure summaries directly to your inbox, all provisioned using Terraform.
Addressing the Challenge
Manual cloud cost monitoring is inefficient and often reactive. AWS Cost Guard offers:
- Proactive Alerts: Email notifications for budget thresholds.
- Daily Recaps: Concise daily email summaries.
- IaC Deployment: Consistent, repeatable, and version-controlled infrastructure.
Architecture Overview
A high-level view of the AWS services orchestrating the Cost Guard solution.
Results & Demonstration
See the AWS Cost Guard in action, from automated budget alerts to daily expenditure summaries delivered right to your inbox.
Daily Cost Recap Email
A sample of the daily cost summary email.
AWS Budgets Console
Monitoring the configured budget alerts.
Ensuring notifications are successfully subscribed.
Implementation Details & Code Highlights
The core Python Lambda function queries the AWS Cost Explorer API and formats the daily spending data for notifications.
Python Lambda Function (`lambda_function.py` excerpt)
import boto3
import os
import json
from datetime import datetime, timedelta
def handler(event, context):
sns_topic_arn = os.environ['SNS_TOPIC_ARN']
ce_client = boto3.client('ce') # Region automatically picked up by Lambda runtime
sns_client = boto3.client('sns')
end_date = datetime.utcnow().date()
start_date = end_date - timedelta(days=1) # Get yesterday's cost
try:
response = ce_client.get_cost_and_usage(
TimePeriod={
'Start': start_date.strftime('%Y-%m-%d'),
'End': end_date.strftime('%Y-%m-%d')
},
Granularity='DAILY',
Metrics=['UnblendedCost']
)
cost_data = response['ResultsByTime'][0]['Total']['UnblendedCost']
amount = float(cost_data['Amount'])
unit = cost_data['Unit']
message = f"Daily AWS Cost Recap for {start_date.strftime('%Y-%m-%d')}:\n" \
f"Total Unblended Cost: {amount:.2f} {unit}\n" \
f"-----------------------------------------\n" \
f"This is an automated notification."
sns_client.publish(
TopicArn=sns_topic_arn,
Message=message,
Subject=f"Daily AWS Cost Recap - {start_date.strftime('%Y-%m-%d')}"
)
print(f"SNS notification sent successfully for {start_date}.")
except Exception as e:
print(f"Error getting cost data or sending SNS: {e}")
raise e # Re-raise for CloudWatch logs to capture errors
return {
'statusCode': 200,
'body': json.dumps('Cost recap processed!')
}
Challenges & Solutions
`AWS_REGION` Environment Variable Conflict
Attempted to set `AWS_REGION` in Lambda, which is a reserved key.
Solution:
Removed `AWS_REGION` from Terraform. Lambda automatically injects it, avoiding conflicts and reinforcing understanding of Lambda's inherent environment variables.
`time_period_start` Format Error in AWS Budgets
Encountered an error with `time_period_start` in `aws_budgets_budget` due to incorrect timestamp format.
Solution:
Modified `formatdate` in Terraform to match AWS Budgets API's specific `YYYY-MM-DD_HH:mm` format, highlighting the importance of API-specific documentation.
AWS Console Region/Account Mismatch
Resources created by Terraform were not visible in the AWS Console.
Solution:
Resolved by verifying and correcting the AWS Console's region and account ID, reinforcing the regional nature of most AWS services.
SNS Subscription Confirmation Emails Not Arriving
Confirmation emails for SNS topic subscriptions were not always reaching the specified `admin_email`.
Solution:
Checked spam/junk, used "Request confirmation" in SNS console, and considered alternative email providers to overcome aggressive spam filters.
Lessons Learned
- Deepened understanding of AWS cloud cost management strategies.
- Reinforced best practices for Infrastructure as Code with Terraform, including state management and dependency resolution.
- Gained practical experience with AWS Lambda, SNS, Budgets, CloudWatch Events, and IAM for building integrated solutions.
- Improved debugging skills for cloud infrastructure deployments, especially common pitfalls like region/account mismatches and API-specific formatting requirements.
- Emphasized the importance of thorough testing and verification of cloud resources post-deployment.