Module env 

Environment-variable reading and ${VAR} / ${VAR:-default} interpolation.

A single primitive shared by every config surface that expands placeholders: the profile loader interpolates a whole YAML document against the process environment, and the services config layer drives interpolate in a multi-pass loop over a secrets→env→vars source chain. Both reuse the one regex and the one unresolved-placeholder rule defined here, so the syntax never drifts between surfaces.

Functions

contains_placeholder

Reports whether input still contains a ${VAR} / ${VAR:-default} placeholder. Used by multi-pass resolvers to detect non-convergence.

interpolate

Replaces every ${VAR} / ${VAR:-default} occurrence in input using lookup.

read_env_optional

Reads an environment variable, treating empty as absent.