Limits & superpowers

The cloud has its limits. And arc itself is an abstraction with deliberate constraints. Whether we label them constraints or limits, they are trade-offs you need to be aware of when designing your software architecture for cloud functions.


Supported services

Architect primitives are based on the following AWS serverless ecosystem services:

Note: with Architect Macros all AWS services supported by CloudFormation can be utilized!


Cloud limits and gotchas

  • Lambda cold starts are vicious on large Lambdas; the best antidote is to author small as possible Lambda functions (rule of thumb: sub 5MB compressed, including modules, usually results in sub-second execution)
  • Lambda functions are time-limited to 5 seconds by default. This can be adjusted, however they cannot execute for longer than 15 minutes maximum. You can also use background tasks to break work down into smaller chunks.
  • CloudFormation templates can only have 200 resources; Architect can nest templates but API Gateway can only support 300 routes and many other limits can apply

Cloud superpowers

  • Less code is faster to write and deploy
  • Determinism that comes as a result of infra as code deployments
  • Extend with the entire AWS ecosystem of services and tools
  • Predictable costs and 100% utilization (scale to zero)
  • Do less of everything: patching, no upgrading, no more orchestration
  • Faster debugging because errors became very shallow in isolation
  • Better isolation also equals better security posture and least privilege by default

Focus on unique business value, only maintain differentiated code and iterate faster with tighter feedback loops.


Next steps