A list of my favorite resources to get an overview and get started:
• GoDoc with comprehensive examples across the API surface area
• Automation API Examples: a repo with end to end walkthroughs for multiple facets including inline programs, git workflows, inline/cli hybrid programs, and multi-stack orchestration
• The source code for Automation API
• halloumi: a prototype of a heroku-like tools that shows what sort of powerful abstractions can be built when infrastructure is just another part of your application code.
• The Pulumi Kubernetes Operator: a real world example of exposing Pulumi behind an API.