AWS has announced significant updates to Lambda logging, introducing volume-based tiered pricing for Amazon CloudWatch Logs and adding Amazon S3 and Amazon Data Firehose as new, cost-effective destinations for Lambda logs. Effective May 1st, 2025, these changes aim to reduce logging costs for high-volume Lambda deployments and offer greater flexibility in integrating with a broader range of monitoring tools.
The move to tiered pricing is particularly welcome news for AWS customers who have experienced the often-hidden costs associated with CloudWatch Logs. As Senior Cloud Architect Mark Lambert noted on LinkedIn:
CloudWatch logs are a common hidden cost gotcha for new AWS customers. Without a strategy, you can quickly burn through your cloud budget and erode stakeholder trust.
The company categorizes the new tiered pricing model for Lambda logs in CloudWatch Logs as Vended Logs, offering progressively lower per-GB costs as log volume increases. For example, in the US East (N. Virginia) region, costs can decrease from $0.50 per GB for the first 10 TB to as low as $0.05 per GB for over 50 TB monthly. As Sandro Volpicella, a freelance software developer, noted on X:
Your CloudWatch Costs could go down by themselves with this launch. AWS counts Logs coming from Lambda now as ‘vented logs,’ and they come with a volume-tiered pricing model.
(Source: Tweet from Sandro Volpicella)
In addition, in a recent Duckbill Group blog post, Eric Pullen notes that while this is a significant benefit for heavy loggers, those using under 10 TB per month per account will see no immediate change, as the first tier matches the previous flat rate.
Adding S3 and Firehose as direct logging destinations for Lambda functions is also a key development. Pullen highlights that this eliminates the need for complex Lambda-based forwarders and unlocks use cases like long-term compliance archiving on S3, advanced analytics, and easier integration with third-party observability platforms via Firehose. However, he hopes that the pricing for these new destinations will become more competitive to encourage broader adoption.
According to Shridhar Pandey and Matthew Barker in the AWS blog post:
These enhancements provide a more straightforward and more cost-effective logging experience for Lambda users.
Pullen echoes this sentiment, emphasizing the potential for substantial cost savings for large enterprises. He also cautions that:
Any custom-written CloudWatch Log reports will need updating due to the pricing change. Additionally, he reminds users that the tiered pricing applies per AWS account, potentially influencing multi-account strategies.
While CloudWatch Logs remains the default logging destination, users can now configure S3 or Firehose as alternatives. AWS encourages users to review the documentation and pricing details to optimize their Lambda logging strategies, including considering log levels and retention policies to maximize cost savings from the new tiered pricing.
(Source: Amazon Compute blog post)
The new logging features are available in all commercial AWS Regions that Lambda and CloudWatch Logs support. Configuration for S3 and Firehose destinations in the Lambda console is initially available in select regions, with more to follow.
