Is AWS ready to provide serverless WebSockets at scale?

Serverless WebSockets at Scale Simon Tabor Software Engineer @simon_tabor

Is AWS ready to provide serverless WebSockets at scale? @simon_tabor
Who am I? @simon_tabor Software Engineer Simon Tabor

Covering… • Our Requirements • AWS AppSync • WebSockets for API Gateway • AWS IoT • Our Solution • The Future!

Key Moments

Product Requirements • Support live events • Users get new Key Moments within 30s • Support catch-up events

System Requirements • Publish updates to users, rather than have the users poll • Retrieve previous messages and subscribe to new messages • Perform with high-traffic on a global scale

Requirements

Why WebSockets?

Why Serverless? Capacity Time Capacity Requirement Autoscaled Capacity

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How it’s sold AppSync aws.amazon.com/appsync/

Pros: GraphQL AppSync

Cons: Authentication AppSync

Cons: Query + Subscribe AppSync

Cons: Global Deployment AppSync

Cons: DynamoDB • Each user performs an AppSync query on connection • 1 AppSync query = 1 DynamoDB query • Limit of 3,000 read-units per second per partition • Limit of 3,000 new users connecting per second per fixture AppSync

Cons: DynamoDB Caching AppSync CloudFront DynamoDB Accelerator ElastiCache

Cons: DynamoDB Caching AppSync

Cons: DynamoDB Solutions • Duplicate data N times when writing to DynamoDB • Front-end selects a random number between 1 and N • Resolves query load for now • Increased costs, higher latency, no single source-of-truth AppSync

Cons: DynamoDB Solutions AppSync

How it’s sold aws.amazon.com/blogs/compute/announcing-websocket-apis-in-amazon-api-gateway/ WebSockets for API Gateway

How it’s sold WebSockets for API Gateway

Pros: Flexible WebSockets for API Gateway • Access to send messages to each individual connection • Incredibly versatile, more control than AppSync • Fully serverless, can use Lambda for all actions

Cons: Broadcasting • Designed for sending specific messages to specific users • Not designed to broadcast a single message to millions of users • Need to invoke a Lambda for each connection and store state in DynamoDB • Need to make an API call to AWS for each connection WebSockets for API Gateway

Cons: Broadcasting WebSockets for API Gateway

How it’s sold AWS IoT aws.amazon.com/iot-core/

Pros: Mature • Mature solution with huge number of features • Many irrelevant for us due to IoT focus • Good monitoring AWS IoT

Cons: Authentication AWS IoT docs.aws.amazon.com/iot/latest/developerguide/protocols.html

≈ Pubby

Requirements • Shared WebSocket connection for Subscribe and Query • Global scale with no race conditions • Minimal operational overhead • Generic for use by other applications? Pubby

Subscriptions Architecture Pubby

Publishing Architecture Pubby

Architecture Pubby

Failovers Pubby 0 750,000 1,500,000 2,250,000 3,000,000 0 mins 2 mins 4 mins 6 mins 8 mins 10 mins 12 mins 14 mins EU Central 1 US East 1

Failovers Pubby

Conclusions

Conclusions • Deals with a specific use-case • Service can be used by other teams at DAZN • Highly-available with seamless regional failover • Single, shared, native WebSocket connection Pubby

Conclusions • AppSync is incredibly powerful • Key Moments requirements are simple • Subscriptions are weakest part of GraphQL • Managed services have downsides • Recommended for a service with many related models AppSync

Conclusions • Opens huge opportunity to use WebSockets • Lack of broadcasting immediate deal-breaker • Great for non-broadcast services • Updates and improvements coming soon? WebSockets for API Gateway

Conclusions • Massive scale • Solution would need to be designed specifically for AWS IoT • Authentication doesn’t suit us AWS IoT

Future? Pubby

Thank you! Simon Tabor Software Engineer @simon_tabor engineering.dazn.com @dazneng

Is AWS ready to provide serverless WebSockets at scale?

Is AWS ready to provide serverless WebSockets at scale?

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