On AWS, INTO the cloud is usually free; OUT to the internet
costs significant per-GB; cross-AZ and cross-region also have
non-trivial fees. The most painful surprise is usually:
A) Free-tier S3 PUTs.
B) Massive internet egress from S3 / EC2 (e.g. serving video without
a CDN, or chatty cross-region replication), and dense cross-AZ
traffic between microservices that aren't pinned by topology.
C) Inbound traffic from users.
D) IAM API calls.Sign in to save your code and track progress across devices.
