Chapter 1: Overview of AWS Lambda

Utilizing AWS Lambda can significantly accelerate service deployment, yet it comes with several notable drawbacks when extensively implemented. Recognizing these limitations is crucial as they typically go unnoticed until production, where they can no longer be avoided.

Section 1.1: Incompatibility of Private API Gateway with Custom DNS

In large-scale software development, employing private networking enhances the security of internal services, safeguarding them from unauthorized access. AWS Lambda facilitates this through AWS VPC configurations. Additionally, utilizing DNS to decouple services is a common practice, allowing for seamless service version updates without altering existing deployments.

However, when employing AWS API Gateway in a private network setup, the use of custom hostnames is restricted. This limitation forces reliance on the AWS API Gateway DNS record, tightly linking it to the underlying infrastructure. Consequently, releasing a new version of a service necessitates infrastructure modifications, heightening the risk of errors and complicating rollbacks.

Section 1.2: The Cost Implications of Application Load Balancer

AWS Application Load Balancer serves as an alternative frontend for AWS Lambda, addressing DNS and networking issues mentioned earlier. Nevertheless, it comes with a significantly higher cost compared to AWS API Gateway.

For instance, in my region, the base cost for AWS ALB is around $18 per month, excluding compute power expenses. While this may appear manageable, organizations often provision numerous AWS Lambdas in a microservices architecture, leading to substantial cumulative costs.

Section 1.3: Security Risks with Exposed Environment Variables

AWS Lambda allows the configuration of environment variables, including sensitive information such as database URLs and passwords. Unfortunately, these configurations can be viewed in the console with read-only permissions, posing a risk of credential exposure when users have access to production with limited permissions.

Depending on your AWS IAM controls and organizational environment, this may affect you differently. A potential workaround is embedding configurations directly into your application zip file; I will explore this solution in a future article, so stay tuned for updates.

Section 1.4: Timeout Constraints with API Gateway and Lambda

AWS Lambda enforces a strict timeout limit of 15 minutes, and when paired with AWS API Gateway, a maximum timeout of 29 seconds. Any request exceeding these limits will result in an error.

To manage these exceptions effectively, it’s crucial to implement measures that return user responses before reaching the timeout limit. This necessitates additional coding to monitor execution duration and cancel processes nearing the threshold. Such timeout constraints complicate the management of long-running tasks, making it more challenging compared to an EC2-based solution that maintains a single open process.

Section 1.5: Throughput Limitations with SQS and Lambda

When AWS SQS is used as a trigger for AWS Lambda, any limitations on Lambda's throughput can lead to error responses for additional requests. These errors can disrupt monitoring systems since they will be reflected in metrics.

Furthermore, if dead letter queues are employed, these errors contribute to the maximum retries per task without even invoking the Lambda function. This can result in legitimate messages being routed to the dead letter queue due to throughput restrictions.

In Conclusion

AWS Lambda is a powerful service that streamlines software development with minimal operational burdens. However, like all tools, it has its limitations, and understanding these is essential. While I frequently leverage AWS Lambda for quick service deployment, transitioning to AWS EC2-based solutions often proves more cost-effective and straightforward in the long run.

Stay connected for more insights or reach out via:

Twitter: @BenTorvo

Email: [email protected]

Website: torvo.com.au

Chapter 2: Additional Resources

Discover the unexpected features of Amazon API Gateway in this insightful AWS re:Invent 2023 session.

Learn the crucial aspects of AWS Lambda that every developer should know in this informative video.