Atmos YAML Functions

Overview

YAML functions are the recommended way to add dynamic behavior to Atmos stack configurations. They use YAML explicit tags (the ! prefix) and operate on structured data after YAML parsing. They cannot break YAML syntax, are type-safe, and produce clear error messages.

Support and timing depend on the file and field. Post-merge stack value functions can use component template results; load-time includes and merge directives run earlier. See references/yaml-functions.md for the scope matrix. Use atmos doctor --only yaml-functions to diagnose misplaced functions without executing them.

Available YAML Functions