Environment-specific configuration for Scala

The problem

Applications often need a shared default configuration, a named environment profile and deployment-specific overrides without duplicating the lookup rules in every call site.

Conceptual summary of the components visible in the source; not a deployment diagram.

What is inside the repository

Profile selection

ACTIVE_PROFILE selects the profile and defaults to local. ROOT_CONFIG_PATH selects the optional top-level file and defaults to /conf/default.conf.

Fallback composition

The wrapper layers the optional file over the selected profile and standard configuration. String/int accessors also consult environment variables using dotted-name to underscore mapping.

A small API and test examples

The class exposes string, integer and nested-config accessors plus confOrElse overloads. SimpleTests and CustomEnvTests demonstrate default and selected-profile behavior.

What this project demonstrates

Reusable abstractions

Extracting recurring deployment configuration behavior into a small library.

Operational clarity

Making profile selection and precedence inspectable.

Testable contracts

Using focused cases to describe configuration lookup behavior.

These are observations about the code and its relevance to engineering work, not claims of production deployment, measured business impact or exclusive authorship.

Inspect the implementation

These links point to the reviewed commit, so the description can be checked against a stable source snapshot.

• README.md ↗

  Intended configuration precedence

• src/main/scala/EnvironmentSpecificConfig.scala ↗

  Actual profile, override and fallback implementation

• src/test/scala/CustomEnvTests.scala ↗

  Selected-profile examples

• src/test/scala/SimpleTests.scala ↗

  Default-profile examples

Verification and reproducibility

Implementation and selected-profile test definitions were reviewed. Tests were not executed and published package distribution was not verified.

Repository command to start with

sbt test

Use the repository README for prerequisites and setup. A listed command is not a promise that an unprepared environment will pass its tests.

Limitations and useful next steps

• Nested getConfig reads file configuration directly rather than applying the string/int environment-variable lookup.
• confOrElse checks the file configuration before choosing a fallback; an environment-only key needs its own explicit expected behavior.
• Tests modify process environment variables through reflection and may need changes for newer JDKs.

What would strengthen the evidence

• Specify precedence for every accessor and add environment-only, missing-key and malformed-value cases.
• Use an injectable environment/config source in tests and publish a verified release example.