Pioneering Serverless Payments at The LEGO Group
Luke Hedger
The LEGO Group
Brick by Brick - Aug 2022
René Magritte
Pioneer of Surrealism
René Magritte challenges us to use ordinary objects in unusual contexts
This is not a pipe
This is not a server
Pioneering Serverless
Payments
September 2018
Brickoin
LEGO.com
Brickbank
20+ Microservices
80+ Lambda functions
100+ GB in DynamoDB
10+ Step Functions workflows
40+ EventBridge rules
Payments platform
Contain complexity
Image from cockroachlabs.com
async
processes
365+ days
shoppers
Scale, scale, scale
Image from leanovia.com
May 4th
What happens after the serverless launch, after the pioneering?
How does mature serverless app stay modern?
Post-Pioneer
Growing up
- Different challenges today vs start
- Stability vs speed
- Serverless has changed
- Architecture and operations may not scale
The tradeoff
DELIVERY SPEED
APP STABILITY
Decisions
| Serverless Things | Start → Scale |
|---|---|
| Delivery pipelines | Start with one, scale to many. Move focus from implementation to delivery |
| Separate concerns | Start with few, scale to many. Collect domain knowledge, avoid wrong abstraction |
| 3rd party tools | Didn't exist (EventBridge) or unproven (CDK). Evolvable architecture |
| Emerging standards | Serverless matures, community grows, discussion amplifies |
| Test strategy | Stability > speed → stability == speed |
| Observability | Unknowns decrease over time |
Finding balance
DELIVERY SPEED
APP STABILITY
Serverless stability is often compromised by complex events
Stability
Plastic events
Consolidate events
Share events cross-application
Standard events
Secure events
Ship!
We need to observe production behaviour ASAP when using managed services
Continuous Serverless Delivery
Serverless SDLC
- Solution design - architecture, service limits
- Targeted refactoring, strangler pattern
- Optimise for test confidence, not coverage
- Isolated service deployments
- Use alarms!
Design → Develop → Test → Release → Observe
∞
Speed up tests by reducing coverage
Serverless Square of Balance
Designing a test strategy allows us to ship at a sustainable rate as our codebase grows
Serverless Test Strategy
Serverless Test Strategy
❌ Test everything all the time
❌ Long-running tests
❌ Too-good tests
❌ Ignore failures/hit retry and 🤞
Identify critical paths ✅
Test against the cloud ✅
Test integration points/event sources ✅
Blend with observability ✅
Until next time...
Work in progress
- Fault tolerance - idempotency
- Observability - less logs, more metrics
- Still learning, still discussing
- More from me twitter.com/level_out
- These slides 🤳👇
