Moving from Serverless to Functionless

What if you could build your next serverless application without a single Lambda function? Let me introduce you to the functionless model: a serverless architecture that emphasizes event-driven, service-based design by connecting AWS services directly, eliminating the need to package, deploy, and manage countless individual Lambda functions.

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1. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved.
2. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Jakub Gaj Cloud Solution Architect
 Danske Bank Moving from Serverless to Functionless
3. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Playlist 1. What is functionless? 2. (Dis)advantages of Lambda functions 3. Modernize your serverless solutions 4. Alice & Bob Telegrams 5. Demo time! 6. Gotchas of the functionless model 7. Key takeaways
4. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. AWS Well-Architected Framework Serverless Applications Lens If your Lambda function is not performing custom logic while integrating with other AWS services, chances are that it may be unnecessary.
5. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Functionless What if you could build your next serverless application without a single Lambda function?
6. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday What does functionless mean? Type of serverless architecture emphasizing direct integration between cloud services, without the need for custom function code. Use Lambda functions to transform data, not to transport data between services.
7. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Key characteristics of functionless model Build around events initiating variety of AWS services Play central role, abstract away operational complexity Workflow orchestration as visual state machines Event-Driven Everything Managed Services Streamlined Workflows
8. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Core managed services for functionless Amazon 
 EventBridge AWS 
 Step Functions AWS 
 AppSync Amazon 
 API Gateway Serverless events router 
 (buses, rules) Serverless GraphQL and pub/sub APIs Serverless RESTful and WebSocket APIs Serverless workflows 
 (state machines)
9. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Lambda in Action Function-as-a-Service: FaaS & Furious
10. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Run Code in the Cloud • Serverless didn’t exist as a term • Revolutionary 100 ms billing • Free Tier included 1M requests • Netflix was an early adopter • Glue code between AWS services
11. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Advantages of Lambda functions Scalability Cost 
 efficiency Quick 
 deployments Reduced 
 Operations
12. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Disadvantages of Lambda functions Cold start latency Execution time limit Limited debugging Provisioned concurrency Parallel processing 
 Data partitioning ECS Fargate tasks Deployment tools 
 (SAM, CDK) Structured logging 
 (Powertools) 
 Logs aggregation Extra libraries
13. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Modernizing serverless applications variety of AWS services Monolithic function 
 (fat Lambda) Microservice-style serverless application Orchestration with workflows (state machines)
14. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Alice & Bob Telegrams Example of a functionless application
15. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Alice & Bob Telegrams Telegraph Station 
 Event Bus Telegraph Station 
 Event Bus Transmission 
 State Machine Transmission 
 State Machine Telegraph Archive 
 DynamoDB Global Table Personal Diary 
 Secrets Manager Address Book 
 Parameter Store London Office Paris Office
16. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Alice & Bob Telegrams
17. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Alice & Bob Telegrams 1. Validate telegram fields 2. Set pricing based on priority level 3. Search addresses in Parameter Store 4. Translate message to French 5. Save telegram in DynamoDB table 6. Emit telegram event to local custom Bus 7. Bus emits event to remote custom Bus Bob’s Transmission Start Pass state Validate Fields Pass state Convert Telegram Choice state Check Priority Pass state Express Counter Wait state Standard Counter Systems Manager: GetParameters Search Address Book Translate: TranslateText Translate Message Fail state Fail Pass state Accept Telegram DynamoDB: PutItem Save in Telegram Archive End EventBridge: PutEvents Transmit Telegram Succeed state Success {% ($states.input.priority) = ("URGENT") %… Default Catch #1 Catch #1 Catch #1 Catch #1
18. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Alice & Bob Telegrams 1. Check telegram’s category 2. Put business messages in Pending Tray 3. Read only the private messages 4. Mark as delivered & add emoji reaction 5. Update telegram in DynamoDB table 6. Update Personal Diary secret 7. Emit event to local Bus for logging Alice’s Transmission Start End Wait state Open Telegram Choice state Check Category Pass state Private Correspondence Pass state Mark as Delivered DynamoDB: UpdateItem Store in Telegram Archive AWS Secrets Manager: PutSecretValue Update Personal Diary Amazon EventBridge: PutEvents Notify Telegraph Succeed state Success Fail state Fail Pass state Business Correspondence Wait state Postpone Amazon SQS: SendMessage Pending Tray {% (($category) = ("PERSONAL")) %} Default Catch #1 Catch #1 Catch #1
19. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Demo + Code Tour Time for a quick demo of Alice & Bob Telegrams
20. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Gotchas Limitations of the functionless model
21. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Does functionless model make sense? JSONata data transformation, no cross-region orchestration Libraries like DynamoDB marshaling, RDS clients, etc. Standard Workflows charged based on nr of state transitions in execution Limitations of ASL External Libraries Pricing Model
22. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Key Takeaways Reimagine your serverless applications
23. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Design principles for serverless applications Single purpose functions Orchestration Efficient processing Functions should be compact, short, single purpose. Each function taking care of speci fi c task. Orchestrate with state machines, not functions. Use AWS SDK integrations with managed services. Use events for triggering asynchronous, just-in-time processing. Design for failure and duplicates.
24. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Get more from AWS with Builder Center bit.ly/awsbc Amazon Q Access the most capable AI- powered coding assistant for software development. Submit requests, discuss, and vote for AWS product and feature improvements. Wishlist Unlock +600 free, digital AWS training courses. Discover community- published articles or create your own. Find and interact with other active AWS builders.
25. © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. #awsdevday Thank you! © 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved. Jakub Gaj jakub@serverless.ninja AWS Builder Profile
 @jakgaj