# Review configuration changes without exposing secrets

Canonical: https://githtml.com/guides/review-configuration-changes
Published: 2026-09-26
Publisher: WaveTech LLC / gitHtml

A configuration review should establish the setting's meaning, default, accepted values, precedence, and effect when absent or invalid. Identify whether changes require a restart and which environments are affected. Review secret handling separately from ordinary settings, and avoid copying live values into a document merely to prove that configuration exists.

## Distinguish configuration from code assumptions

An illustrative export limit may be declared in an environment variable but overridden by a runtime setting or a hard-coded boundary elsewhere. Trace the effective value rather than reviewing only its name. The Twelve-Factor App discusses configuration that varies between deployments; that principle does not establish how a particular codebase implements precedence. Record where the setting is read, how it is parsed, and what happens when it is missing. A documented default should be supported by the implementation for the reviewed version.

## Review the change across supported states

Suppose an illustrative timeout changes from optional to required. Examine fresh environments, existing deployments, and an invalid value. Ask whether startup fails clearly, silently falls back, or proceeds with an unintended value. Verify units and accepted range; a number without units is easy to misinterpret. Review whether an updated setting is read dynamically or only at startup. Do not test production configuration casually. A saved example should use unmistakable placeholders and retain only the structure necessary to explain the behavior.

1. Meaning: state the setting's purpose, units, range, and default.
2. Precedence: identify every source that can affect the effective value.
3. Lifecycle: explain validation, reload behavior, compatibility, and removal policy.

## Document the operational consequence

If a change requires coordinated updates, identify the owner and the order of operations in the separate approved plan. A read-only review should report missing prerequisites, not make configuration changes itself. Distinguish a secret reference from a secret value and link to the approved access procedure instead of embedding credentials. Put the change summary and unresolved questions at the top of the HTML packet for mobile review. Keep dated environment evidence clearly labeled so an old snapshot is not mistaken for the currently active configuration.

## Sources and further reading

- [The Twelve-Factor App: Config](https://12factor.net/config)
- [GitHub Docs: Getting permanent links to files](https://docs.github.com/en/repositories/working-with-files/using-files/getting-permanent-links-to-files)

## Related guides

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- [Review a PostgreSQL query-plan report safely](https://githtml.com/guides/review-postgresql-query-plan-report)
- [Review performance claims without being fooled by one fast run](https://githtml.com/guides/review-performance-claims-with-distributions)
- [Review test coverage by reading assertions, not percentages](https://githtml.com/guides/review-test-coverage-by-assertions)

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