Making sense of AWS Serverless operations- AWS Community Day CEE 2025

There is a misunderstanding, that everything is possible with the Serverless Services in AWS, for example that your Lambda function may scale without limitations. But each AWS service (not only Serverless) has a big list of quotas that everybody needs to understand and take into account during the development.

In this talk I'll explain the most important things to be aware of for the scalability of the AWS Serverless services, explain quotas (from the hyper scalability point of view, but not only) of the services like API Gateway, Lambda, DynamoDB, Aurora Serverless, SQS, S3 and others and how to architect your solution with these quotas and technical concepts of the distributed systems in mind like token bucket algorithm, throughput and burst rate, concurrency, retry with exponential backoff and jitter and others.

I'll also talk about some general architetural decision what services to use in the Serverless applications: DynamoDB or Aurora (Serverless) for the database choice and SQS, SNS, Kinesis or EventBridge in case you use asynchronous communication/event-driven patterns.

1. Making sense of AWS Serverless operations
Vadym Kazulkin, ip.labs , AWS Community Day CEE , October 16 2025

2. Vadym Kazulkin
ip.labs GmbH Bonn, Germany
Co-Organizer of the Java User Group Bonn
[email protected]
@VKazulkin
https://dev.to/vkazulkin
https://github.com/Vadym79/
https://de.slideshare.net/VadymKazulkin/
https://www.linkedin.com/in/vadymkazulkin
https://www.iplabs.de/
Contact

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The future of the software development (prioto LLMs)

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Challenges and lessons learned
Architect with AWS Serverless quotas and technical concepts in mind
General architectural decisions
SQS vs SNS vs Kinesis vs EventBridge
Aurora (Serverless) vs DynamoDB vs Aurora
DSQL
Challenging Serverless observability

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Serverless Application

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Service Quotas

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Service Quotas

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account and current region limits
Service Quotas

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Service Quotas

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Service Quotas Request History

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Service Quotas Automatic Management

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Service Quotas Automatic Management

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Serverless Application

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https://aws.amazon.com/de/blogs/compute/building-well-architected-serverless-applications-controlling-serverless-api-access-part-2/
https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-request-throttling.html
•The throttle ratethen determines how
many requests are allowed per second
•The throttle burstdetermines how many
additional requests are allowed per
second
API Gateway throttling-related settings are
applied in the following order:
•Per-client or per-method throttling limits
that you set for an API stage in a usage
plan
•Per-method throttling limits that you set
for an API stage
•Account-level throttling per Region
•AWS Regional throttling
Token bucket algorithm
API Gateway Token Bucket Algorithm

15. Quota Description Value Adjustable
Default
throughput /
Throttle rate
The maximum number of requests per
second that your APIs can receive
10.000
Throttle burst rateThe maximum number of additional
requests per second that you can send in
one burst
5.000
API Gateway Important Service Quotas

16. Quota Description ValueAdjustableMitigation
Max timeoutThe maximum integration
timeout in milliseconds
29 sec 1) Increase the limit
2) Lambda Function URL
with response streaming
API Payload
size
Maximum payload size for
non WebSocket API
10 MB 1)The client makes an
HTTP GET request to API
Gateway, and the
Lambda function
generates and returns a
presignedS3 URL
2)The client uploads the
image to S3 directly,
using the resigned S3
URL
API Gateway Important Service Quotas

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Serverless Application

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https://docs.aws.amazon.com/lambda/latest/dg/lambda-concurrency.html
Concurrencyis the number of in-flight requests your AWS Lambda function is
handling at the same time
Lambda Concurrency

19. Quota Description Value Adju
stab
le
Mitigation
Concurrent
executions/
Concurrency
limit
The maximum number of
events that functions can
process simultaneously in
the current region
1.000 Rearchitect
Burst
Concurrency
Limit
After the initial burst,
concurrency scales by 1000
executions every 10
seconds up to your account
concurrency limit. Each
function within an account
now scales independently
from each other
•US West (Oregon), US
East (N. Virginia), Europe
(Ireland)=3.000
•Asia Pacific (Tokyo),
Europe (Frankfurt), US
East (Ohio)=1000
•All other Regions=500
Use
provisioned
concurrency
Lambda Important Service Quotas New

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https://aws.amazon.com/de/blogs/aws/aws-lambda-functions-now-scale-12-times-faster-when-handling-high-volume-requests/
Lambda Concurrency and throttling

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https://aws.amazon.com/de/blogs/compute/understanding-aws-lambdas-invoke-throttle-limits/
Lambda concurrencylimit is a limit on the
simultaneous in-flight invocations allowed at
the same time
Transaction per second (TPS) =
concurrency / function duration in
seconds
Lambda Concurrency and TPS

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Lambda Function level Concurrency

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•Optimize for cost-performance
•Use AWS Lambda Power Tuning
•Reuse AWS Service clients/connections outside of the Lambda
handler
•Use a keep-alive directive to maintain persistent connections
•Use the newest version of AWS SDK of programming language of your
choice
•Import only dependencies that you need (especially from AWS SDK)
•Minimize dependencies and package size
•Implement (other) best practices to reduce cold starts
https://docs.aws.amazon.com/lambda/latest/dg/best-practices.html
General Best Practices for using Lambda

24. Quota Description Value AdjustableMitigation
Function
timeout
The maximum timeout
that you can configure for
a function
15 min
Synchronous
payload
The maximum size of an
incoming synchronous
invocation requestor
outgoing response
6 MB For the Request:
•use API Gateway
serviceproxy to S3
•use pre-signed S3 URL and
upload directly to S3
For the Response:
Use response streaming (with
AWS Lambda Web Adapter )
https://theburningmonk.com/2020/04/hit-the-6mb-lambda-payload-limit-heres-what-you-can-do/
Lambda Important Service Quotas

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Serverless Application

26. Quota Description Value Adjustable
Throughput
per Standard
Queue
Standard queues support a nearly unlimited
number of transactions per second (TPS) per
API action.
Nearly
unlimited
SQS (Standard) Important Service Quotas

27. Image: burst.shopify.com/photos/a-look-across-the-landscape-with-view-of-the-seahttps://aws.amazon.com/about-aws/whats-new/2023/11/aws-lambda-polling-scale-rate-sqs-event-source/?nc1=h_ls
https://aws.amazon.com/blogs/compute/introducing-faster-polling-scale-up-for-aws-lambda-functions-configured-with-amazon-sqs/
•When a Lambda function subscribes to an SQS
queue, Lambda polls the queue as it waits for
messages to arrive. It consumes messages in
batches, starting with 5functions at a time
•If there are more messages in the queue, Lambda
adds up to 300functions/concurrent executions
per minute, up to 1250 concurrent executions, to
consume those messages from the SQS queue
•This scaling behavior is managed by AWS and
cannot be modified
•To process more messages, you can optimize your
Lambda configuration for higher throughput
Lambda scaling with SQS standard queues

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https://aws.amazon.com/de/blogs/compute/understanding-how-aws-lambda-scales-when-subscribed-to-amazon-sqs-queues/
https://docs.aws.amazon.com/lambda/latest/dg/with-sqs.html#services-sqs-batchfailurereporting
•Increase the allocated memory for your Lambda
function
•Optimize batching behavior:
•by default, Lambda batches up to
10 messagesin a queue to process them
during a single Lambda execution. You can
increase this number up to 10,000messages,
or up to 6MBof messages in a single batch
for standard SQS queues
•If each payload size is 1MB(the maximum
message size for SQS), Lambda can only take
6messagesper batch, regardless of the batch
size setting
•Implement partial batch responses
Lambda scaling with SQS standard queues

29. Quota Description Value Adjustable
Throughput
per Standard
Queue
Standard queues support a nearly unlimited
number of transactions per second (TPS) per
API action.
Nearly
unlimited
Message size The size of a message 256KB ->
recently
increased
to 1MB
SQS (Standard) Important Service Quotas

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The BatchWriteItemoperation puts
or deletes multiple items in one or
more tables.
A single call to BatchWriteItemcan
transmit up to 16MBof data over
the network, consisting of up to
25 item put or delete operations.
use BatchWriteItem
https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html
Use BatchWriteItemrequest for storing to DynamoDB

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AWS services such as S3, SNS, EventBridge
and others invoke Lambda functions
asynchronously.
Lambda uses an internal queue to store
events. A separate process reads events from
the queue and sends them to the function.
https://aws.amazon.com/blogs/compute/introducing-new-asynchronous-invocation-metrics-for-aws-lambda/
Asynchronous invocations of Lambda functions

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https://docs.aws.amazon.com/lambda/latest/dg/invocation-async.html
Asynchronous invocations of Lambda functions and retry
behavior
Lambda discards events from its event queue if the retry policy has
exceeded the number of configured retries or the event reached its
maximum age.
The event once discarded from the event queue goes to the destination or
DLQ, if configured.

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More Serverless services, more service quotas ☺
•CloudFront
•EventBridge
•SNS
•Kinesis
•StepFunctions
Services Quotas of other Serveressservices

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•Understand the concepts of distributed systems
•Token Bucket Algorithm
•How asynchronous invocation patterns work
•polling from the queue and synchronously invoke Lambda
function
•Retries with (exponential) backoff pattern and jitter, load-
shedding and how AWS services and AWS SDKs support them
•Understand individual service specific terms
•Concurrency, transactions per second (TPS)
•Throttle/Concurrency limit, burst limit
•Event Source Mapping (ESM)
Understand Technical Concepts

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•Know, understand and observe the service quotas
•Architect with service quotas in mind
•AWS adjusts them from time to time
•In case I’d like to request the quota increase, provide a valid
justification for the new desired value
•Service quotas are valid per AWS account (per region)
•Use different AWS accounts for development and testing
•Use different AWS accounts for independent (micro-)services
•Separate AWS accounts on the team level
•Use AWS Organizations
General best practices for Service Quotas

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It’s also about latency

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Challenges and lessons learned
Architect with AWS Serverless quotas and technical concepts in mind
General architectural decisions
SQS vs SNS vs Kinesis vs EventBridge
Aurora (Serverless) vs DynamoDB vs Aurora
DSQL
Challenging Serverless observability

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When to use SQS, SNS, Kinesis and EventBridge
https://www.serverlessguru.com/tips/sqs-vs-sns-vs-kinesis-vs-eventbridge

39. Database Choice
DynamoDB Aurora Aurora
Serverless
vs vs vs
Aurora
DSQL

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Challenges and lessons learned
Architect with AWS Serverless quotas and technical concepts in mind
General architectural decisions
SQS vs SNS vs Kinesis vs EventBridge
Aurora (Serverless) vs DynamoDB vs Aurora
DSQL
Challenging Serverless observability

41. Current architecture our image storage solution
You need
•Observability (Logging, Monitoring, Tracing)
•Alerting
•Incident Management solution (PagerDuty)
https://aws.amazon.com/blogs/compute/introducing-new-asynchronous-invocation-metrics-for-aws-lambda/

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The future of the software development (prioto LLMs)

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Serverless reduces the need for (readily
available) ops skills but increases the
demand for (less readily available)
distributed system design skills.
https://architectelevator.com/cloud/serverless-illusion/
Serverless challenges

44. Ask Me Anything and Feedback
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Thank you