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New pkg/function Package for Format-Agnostic Function Registry

· One min read
Erik Osterman
Erik Osterman
Founder @ Cloud Posse

Introduces pkg/function/, a new format-agnostic function registry that consolidates YAML function handlers into a reusable package.

What Changed​

This release adds foundational packages for modular function handling:

  • pkg/function/: Format-agnostic function registry with handlers for all YAML functions (!env, !exec, !terraform.output, !store.get, !literal, etc.)
  • pkg/yaml/: YAML-specific utilities for position tracking and error handling
  • pkg/aws/identity/: Consolidated AWS identity caching (moved from internal/aws_utils)

Why This Matters​

The function registry separates concerns between format-specific parsing (YAML, HCL, JSON) and format-agnostic function execution. This enables:

  • Code Reuse: Single registry used across all configuration formats
  • Extensibility: New functions can be added without modifying core parsing logic
  • Testing: Interface-driven design with dependency injection for better testability
  • Plugin Architecture: Foundation for future plugin support

Technical Details​

Functions are organized by execution phase:

  • PreMerge: !env, !exec, !random, !template, !include, !literal
  • PostMerge: !terraform.output, !terraform.state, !store.get, !aws.*

The registry provides thread-safe registration, lookup by name or alias, and phase-based filtering.

Get Involved​

This is preparatory work for broader YAML processing refactoring. Contributions and feedback are welcome at github.com/cloudposse/atmos.