Serverless gives us the power to focus on writing code without worrying about the provisioning and ongoing maintenance of the underlying compute resources. Cloud providers (like AWS) also give us a huge number of managed services that we can stitch together to create incredibly powerful and massively scalable serverless microservices. This talk focuses on common design patterns that can be used to implement serverless microservices in AWS.

1. Serverless Microservice
Patterns for AWS
Jeremy Daly
CTO, AlertMe.news
@jeremy_daly

2. Jeremy Daly
• CTO at AlertMe.news
• Consultant that works with companies building in the cloud
• 20+ year veteran of technology startups
• Started migrating workloads to the cloud in 2009
• Blogger, open-source contributor, speaker
• Publish Off-by-none, a weekly newsletter about serverless
@jeremy_daly

3. Agenda
• Serverless Microservices ⚡
• Communication Types ☎
• Serverless Microservice Patterns 🌀
• Serverless Microservice Best Practices 🏅
• Next steps 🤔
@jeremy_daly

4. Serverless Microservices ⚡
• Multiple functions and managed components per service
• Functions are independently configurable and scalable
• Functions can have separate IAM roles
• Functions can use different runtimes
• Functions are stateless ⚠
@jeremy_daly

5. Communication Types ☎
• Synchronous Communication ⏳
Services can be invoked by other services and must wait for a reply.
This is considered a blocking request, because the invoking service
cannot finish executing until a response is received.
• Asynchronous Communication 🚀
This is a non-blocking request. A service can invoke (or trigger)
another service directly or it can use another type of communication
channel to queue information.The service typically only needs to
wait for confirmation (ack) that the request was received.
@jeremy_daly

6. Serverless Microservice Patterns
WARNING: Poorly named patterns ahead

7. The SimpleWeb Service
Client
API Gateway Lambda DynamoDB
@jeremy_daly

8. The Gatekeeper
Client API Gateway DynamoDB
IAM Policy
DynamoDBCognito
Authorization Service
Lambda
Lambda
Authorizer
@jeremy_daly

9. RDS
The ScalableWebhook
Client API Gateway
SQS
Queue
SQS
(DLQ)
Lambda Lambda
(throttled)
ack
“Asynchronous”
Request
Synchronous
Request
@jeremy_daly

10. The Internal API
Client
w/ AWS-SDK
DynamoDBLambda
SQS
(DLQ)
Client
w/ AWS-SDK
DynamoDBLambda
“Asynchronous”
Request
ack
The Internal Handoff
Lambda invoke()
InvocationType: “RequestResponse”
Lambda invoke()
InvocationType: “Event”
Synchronous
Request Serverless Microservice
Avoid API Gateway with internal invocations
Beware of synchronous chaining
@jeremy_daly

11. The FIFOer
Client
w/ AWS-SDK
DynamoDB
SQS Queue
(FIFO)
SQS
(DLQ)
Lambda
(concurrency of 1)
ack
“Asynchronous”
Request
CloudWatch Rule
(trigger every minute)
InvocationType: “Event”
Be sure to avoid cascading effects (this is an exception)
@jeremy_daly

12. The Strangler
Client API Gateway
DynamoDBLambda
ELB
Serverless Microservice
Legacy App
API Gateway adds latency and can be expensive
HTTP_PROXY
IntegrationType
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13. ALB
The (Better) Strangler
Client
DynamoDBLambda
Serverless Microservice
Legacy App
ALBs don’t support Custom Authorizers, Usage Plans, API Keys, etc.
Lambda
TargetType
@jeremy_daly
Advanced Request Routing
• HTTP headers and methods
• Query parameters
• Source IP

14. hit
The Read Heavy Reporting Engine
Client API Gateway RDSLambda
Elasticache
Key Points:
• Make sureTTLs are set appropriately
• Include the ability to invalidate cache
• Create new RDS connections ONLY on misses
@jeremy_daly

15. Lambda
The Fan-Out / Fan-In
Client DynamoDB
LambdaWorker
LambdaWorker
LambdaWorker
S3 Bucket
OR
Collect Results (Fan-In)
Concurrent Executions
of the SAME function
“Asynchronous”
Request
SQS
(DLQ)
ack
SQS
(DLQ)
@jeremy_daly

16. The Eventually Consistent
Client API
Gateway
DynamoDB
SQS
(DLQ)
Lambda Lambda
(throttled)
RDS
DynamoDB
Stream
Serverless Microservice
Key Points:
• DynamoDB Streams work like Kinesis, batches are retried
• You must manage your own Dead Letter Queue (DLQ)
• Include a last_updated field to limit your SQL query
Synchronous
Request
@jeremy_daly

17. Twilio API
The Circuit Breaker
Client API Gateway Lambda
ElasticacheKey Points:
• Cache your cache with warm functions
• Use a reasonable failure count
• Cost (and frustration) saver for synchronous requests
Status
Check CLOSED
OPEN
Increment Failure Count
HALF OPEN
“Everything fails all the time.”
~WernerVogels
@jeremy_daly

18. The Notifier
Key Points:
• SNS has a “well-defined API”
• Decouples downstream processes
• Allows multiple subscribers with message filters
Client
SNS
“Asynchronous”
Request
ack
Serverless Microservice
@jeremy_daly
HTTP
SMS
Lambda
SQS
Email

19. @jeremy_daly
The Event Fork
“Asynchronous”
Request
ack
SQS
Queue LambdaSNS
Topic
DynamoDBClient API
Gateway
Lambda
Event processing pipeline
SQS
Queue Lambda Kinesis Firehose
Event Search & Analytics pipeline
Elasticsearch
S3 Dead Letter Bucket
SQS
Queue Lambda Kinesis Firehose
Event Storage & Backup pipeline
S3 Backup
Bucket
amount > $100
Key Points:
• Common patterns that can be reused
• Filters allow you to control pipeline data
• SNS to SQS is “guaranteed” (100,010 retries)

20. Serverless Microservice Best Practices🏅
• Services should have their own private data
• Services should be independently deployable
• Utilize eventual consistency
• Use asynchronous processes whenever possible
• Keep services small, but valuable
@jeremy_daly

21. Where do we go from here? 🤔
• Loose Coupling and High Cohesion
• Function Composition
• Orchestration versus Choreography
• State Machines (AWS Step Functions)
• Lambda Layers & Nested Applications
@jeremy_daly

22. Things I’m working on…
Blog: jeremydaly.com
Newsletter: Offbynone.io
Lambda API: LambdaAPI.com
Podcast: ServerlessChats.com
GitHub: github.com/jeremydaly
Twitter: @jeremy_daly
@jeremy_daly

23. ThankYou!
Jeremy Daly
jeremy@jeremydaly.com
@jeremy_daly