[jranson]

Description

This expands environment var string replacement to all YAML values, rather than just specific values typed as EnvString. Instead of interpolating ${ENV_NAME} for EnvString fields during YAML unmarshaling, this change finds and interpolates all ${ENV_NAME} values across the config prior to the unmarshal step, while the EnvString and EnvStringMap types are retired.

The secret.Secret remains as a string type variant that returns <secret> from String(), and additional fields (e.g., redis credentials) are chnaged to Secret to prevent spilling in the sanitized config.

Because Request Rewriters use the ${1} or ${genericCaptureFieldname} formats for regex captures, that section requires env values to start with TRK_ (e.g,. ${TRK_REWRITER_FALLBACK_BACKEND}) to interpolate. The TRK_ prefix requirement does not apply to config sections outside of Request Rewriters.

Type of Change

• • Bug fix
• • New feature
• • Optimization
• • Test coverage
• • Documentation
• • Infrastructure

AI Disclosure

• • This contribution DOES NOT include AI-generated changes
• • This contribution DOES include AI-generated changes, and I have reviewed the relevant contributing guidelines.