feat(server): rfc0020 green pt1 — env-substitution resolver by jensholdgaard · Pull Request #322 · jensholdgaard/ourios

jensholdgaard · 2026-06-30T19:23:20Z

What

RFC 0020 green slice 1 — the environment-variable substitution resolver (config::env_subst), the pure, gnarly core of the config-file mechanism.

resolve(scalar, lookup) -> Result<String, MalformedReference> operates on a single scalar value following the OTel Config WG data model:

${env:NAME} / ${NAME} (equivalent); ${NAME:-default} with default on unset or empty; undefined-no-default → empty.
$$ escapes a literal $; resolved values are inserted verbatim and never re-scanned (non-recursive — no structure injection, the §3.3 security boundary).
Malformed ${…} → MalformedReference naming the reference only, never a value (RFC 0019 §3.4 hygiene).
Optional env: prefix backtracks per the WG grammar (${env:-x} = name env, default x); unterminated ${ is literal.

Tests

The OTel Config WG worked-example vector table (string-level rows) — the normative conformance set.
proptest invariants: never panics, $-free identity, verbatim/non-recursive value insertion, $$→$ escaping.
Plus targeted unit tests (default unset/empty, env-prefix equivalence + backtrack, malformed naming, unterminated literal).

Scope

Foundational + additive — lives in the lib (unit-testable), no binary behaviour change; the rfc0020_config_file stubs stay ignored (6). RFC0020.2 fully closes in the next slice (the YAML walk: scalar-only, keys verbatim, type-after-substitution). OTEL_* stays out of scope (§3.8).

fmt / clippy --all-targets -D warnings / cargo doc / tests clean locally.

🤖 Generated with Claude Code

Summary by CodeRabbit

New Features
- Added support for environment-variable substitution in server configuration values, including default fallbacks and escaped dollar signs.
- Improved configuration handling so unresolved or malformed references are reported clearly instead of failing unexpectedly.
- Expanded test coverage for configuration substitution behavior and edge cases.

The pure substitution resolver (config::env_subst) for the RFC 0020 config file: resolve(scalar, lookup) following the OTel Config WG model on one scalar value — ${env:NAME}/${NAME}, ${NAME:-default} (default on unset OR empty), $$ escape, undefined-no-default → empty, values inserted verbatim (non-recursive, no structure injection), malformed ${…} refs → a MalformedReference naming the reference only (never a value; §3.4 hygiene). The optional env: prefix backtracks per the WG grammar (${env:-x} = name env, default x). Unterminated ${ is literal. Tested: the OTel WG worked-example vector table (string-level rows) + proptest invariants (no-panic, $-free identity, verbatim/non-recursive value insertion, $$→$ escaping). Lives in the lib so it's unit-testable. Foundational — additive only; the rfc0020 stubs stay ignored. RFC0020.2 closes in the next slice (the YAML walk: scalar-only, keys verbatim, type after substitution). OTEL_* stays out of scope (§3.8). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

coderabbitai · 2026-06-30T19:23:38Z

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Review details

⚙️ Run configuration

Configuration used: defaults

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Run ID: 10722a45-bdf1-4c4f-b216-404f5f436f7a

📥 Commits

Reviewing files that changed from the base of the PR and between a2623e1 and b29db83.

📒 Files selected for processing (1)

crates/ourios-server/src/config/env_subst.rs

📝 Walkthrough

Walkthrough

This PR adds a new config module to ourios-server implementing RFC 0020 ${...} environment-variable substitution. It introduces a resolve function and MalformedReference error type, wires the module into the crate's public surface, and adds a pinned proptest dev-dependency along with unit and property-based tests.

Changes

Config environment substitution

Layer / File(s)	Summary
Config module entrypoint and crate wiring `crates/ourios-server/src/config.rs`, `crates/ourios-server/src/lib.rs`	Adds module documentation for the RFC 0020 config work, re-exports `env_subst`, and registers `pub mod config;` in the crate root.
Substitution resolver implementation `crates/ourios-server/src/config/env_subst.rs`	Implements `MalformedReference` and `resolve`, performing left-to-right scanning with `$$` escaping, `env:` prefix and `:-default` handling, identifier grammar validation, and non-recursive substitution.
Unit and property tests for resolver `crates/ourios-server/src/config/env_subst.rs`, `crates/ourios-server/Cargo.toml`	Adds unit and proptest-based tests covering worked examples, default/empty semantics, escape and backtracking behavior, and panic-free resolution, supported by a pinned `proptest` dev-dependency.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

A dollar sign hopped down the trail,
With curly braces for a tail,
"env:" whispered soft and low,
Defaults bloom where values don't grow,
Tests hop wild through proptest's den,
No panics found — hooray, again! 🐇🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately highlights the main change: the RFC 0020 environment-variable substitution resolver.
Description check	✅ Passed	The description covers summary, tests, and scope, but it omits the template's Related section and checklist items.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch feat/rfc0020-green-env-subst

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Copilot

Pull request overview

Adds the first “green slice” of RFC 0020 config-file support to ourios-server by introducing a unit-testable environment-variable substitution resolver (config::env_subst) and wiring a new config module into the server library.

Changes:

Introduces config::env_subst::resolve with RFC/OTel Config WG-style ${…} substitution semantics plus a MalformedReference error type.
Adds a comprehensive conformance + property-test suite for the resolver using proptest.
Exposes the new config module from ourios-server’s library crate and updates dev-dependencies/lockfile.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
crates/ourios-server/src/lib.rs	Exposes `config` from the server library and updates crate-level docs to mention RFC 0020 config pieces.
crates/ourios-server/src/config.rs	Adds the new `config` module root and documents intended RFC 0020 scope.
crates/ourios-server/src/config/env_subst.rs	Implements the env-substitution resolver + `MalformedReference`, with unit and property tests.
crates/ourios-server/Cargo.toml	Adds `proptest` dev-dependency for resolver property tests.
Cargo.lock	Records the new `proptest` dependency in the lockfile.

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Review raised that the `$$` split could "break" a `${…}` whose default contains `$$`. That is the WG algorithm by design — it is escape-first ("match the content since the prior escape against SUBSTITUTION-REF"), so a `$$` inside a would-be reference breaks it; the normative table already covers this (`${X:-$${Y}}` → `${X:-${Y}}`, a passing case). Add explicit tests pinning `${NAME:-foo$$bar}` → `${NAME:-foo$bar}`, `${A$$B}` → `${A$B}` (not a malformed-ref error), and `${A:-foo$bar}` → `foo$bar` (a single `$` is part of a default), and clarify the resolve/segment docs. No resolver-logic change. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

Two review fixes: format the malformed reference with {:?} so one containing whitespace/newlines stays delimited and legible in logs, and correct the "brace-free" comment — a reference body has no `}` but may contain `{` (the nested-default case). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Rust regex `.` excludes `\n`, so `.*` / `.{0,32}` did not generate newlines — yet config scalars / env values can be multi-line (the WG's own INVALID_MAP_VALUE is). Switch never_panics + value_inserted_verbatim to `(?s)` so the generators truly cover arbitrary, multi-line input. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated no new comments.

jensholdgaard requested a review from Copilot June 30, 2026 19:23

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jensholdgaard requested a review from Copilot June 30, 2026 19:34

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jensholdgaard merged commit d0d6b22 into main Jun 30, 2026
21 checks passed

jensholdgaard deleted the feat/rfc0020-green-env-subst branch June 30, 2026 19:51

coderabbitai Bot mentioned this pull request Jul 6, 2026

feat(server): rfc 0026 green a — the token store (RFC0026.1) #390

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feat(server): rfc0020 green pt1 — env-substitution resolver - #322

feat(server): rfc0020 green pt1 — env-substitution resolver#322
jensholdgaard merged 4 commits into
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