feat(server): OURIOS_COMPACTION_ENABLED to disable a pod's compaction sweep

[jensholdgaard]

What

Adds OURIOS_COMPACTION_ENABLED (default on) to ourios-server. When set to a falsey value (0/false/no/off), the process skips building and running the compaction sweep entirely. This is opt-out (unlike the opt-in OURIOS_RECEIVER_ENABLED / OURIOS_QUERIER_ENABLED roles).

Why

The binary unconditionally ran the background compaction sweep, so a multi-pod deployment (receiver StatefulSet + querier Deployment + compactor) had every pod sweeping on its interval. publish_cas makes concurrent sweeps correct (losers no-op), but it's redundant load — N pods each listing the bucket every interval. This flag lets the Helm chart disable compaction on the receiver + querier pods so a single dedicated compactor sweeps (the clean topology for the S3-native chart, workstream C).

Behavior / invariants

• Default-on → no behavior change for existing single-process or default deployments.
• When disabled, the process builds no Compactor and no audit sink; the run loop runs the receiver/querier (if enabled) + waits for SIGINT/SIGTERM (the compaction branch is a pending future).
• Hazard docs: apply RFC maturity-model amendments #4 (small-file problem): unchanged for any deployment that keeps at least one sweeper running. Disabling compaction on every pod (no dedicated compactor) is an operator misconfiguration — the chart wires exactly one dedicated compactor. publish_cas (RFC 0009 §3.2 / RFC0013.3-4) keeps any concurrent sweeps safe regardless.
• WAL / data-store wiring unchanged (RFC 0019).

Tests

build_config_compaction_is_opt_out (default + non-falsey → on; 0/false/no/off/trimmed → off); rfc0019_7 asserts default-on. cargo fmt, clippy -D warnings, cargo test -p ourios-server (20 passed), cargo doc -D warnings — all green.

Follow-on

The S3-native Helm chart (workstream C) sets OURIOS_COMPACTION_ENABLED=0 on the receiver + querier workloads and leaves it default-on for the dedicated compactor Deployment.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Added an opt-out setting for background compaction, enabled by default and configurable through an environment variable.
  • Improved shutdown behavior so the server still stops cleanly whether compaction is enabled or disabled.

• Bug Fixes

  • Clarified and tightened configuration handling for compaction timing and enablement values.
  • Updated defaults and checks so compaction behavior matches the documented environment settings.

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 8c3b9f5a-dd9a-47a6-a02a-8ca25869b34b

📥 Commits

Reviewing files that changed from the base of the PR and between b93b292 and 846a948.

📒 Files selected for processing (1)

• crates/ourios-server/src/main.rs

📝 Walkthrough

Walkthrough

Adds compaction_enabled: bool to ServerConfig, controlled by a new OURIOS_COMPACTION_ENABLED env var that defaults to on. build_config gains a compaction_enabled_raw parameter with opt-out parsing. In main, the Compactor and ParquetAuditSink are constructed conditionally; the shutdown select! uses pending() for the disabled branch.

Changes

Compaction Opt-Out Control

Layer / File(s)	Summary
ServerConfig field and build_config parsing crates/ourios-server/src/main.rs	Adds compaction_enabled: bool to ServerConfig, extends build_config to accept compaction_enabled_raw with opt-out semantics (enabled unless explicitly falsey), and updates config_from_env to pass OURIOS_COMPACTION_ENABLED.
Conditional Compactor wiring in main crates/ourios-server/src/main.rs	Constructs Compactor and ParquetAuditSink only when config.compaction_enabled is true; uses pending() for the disabled branch in the shutdown select!.
Test updates and new opt-out assertions crates/ourios-server/src/main.rs	Updates all build_config call sites to the new signature and adds assertions verifying default-enabled behavior and explicit falsey token disabling.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A flag in the env, a toggle so neat,
Compaction runs on, or steps back from its beat.
Default is true, unless told to rest,
"0", "false", or "no" — the rabbit knows best.
Pending forever when sleeping, no fuss,
The burrow stays tidy — leave shuffling to us!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the PR’s main change: adding an opt-out flag to disable compaction sweeps.
Description check	✅ Passed	The description is substantive and covers summary, rationale, behavior, and tests, though it doesn’t follow the exact template headings.
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 rfc0019-compaction-enable-flag

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[Copilot]

Pull request overview

Adds an opt-out switch for the server’s background compaction role so multi-pod deployments can run compaction on a single dedicated pod while other pods focus on receiver/querier roles.

Changes:

• Introduces OURIOS_COMPACTION_ENABLED (default on) and threads it through config assembly.
• Makes compactor/audit-sink construction conditional and keeps the main loop alive via a pending future when compaction is disabled.
• Adds unit tests validating the opt-out behavior.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/ourios-server/src/main.rs`:
- Around line 411-441: The compaction branch in main should emit subsystem
telemetry for both states and stop using stderr for hot-path failures. Update
the `compactor`/`compaction` flow to publish a Prometheus metric or gauge
indicating whether compaction is enabled or disabled for this pod, and make sure
the disabled `None` path records that state explicitly. Replace the `eprintln!`
calls inside `Compactor::run`’s callback with structured Ourios logging (using
the server’s logging path) so sweep errors and `compaction sweep failed` are
visible in telemetry with context.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 1b398417-a2b0-4307-a67a-43d4c88275cf

📥 Commits

Reviewing files that changed from the base of the PR and between 75f0139 and b93b292.

📒 Files selected for processing (1)

• crates/ourios-server/src/main.rs

[Copilot]

Pull request overview

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

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.