feat(ingester): tenant derivation + fan-out (RFC0003.3/.4)

[jensholdgaard]

What

Fourth green slice of the OTLP receiver (RFC 0003 §6.3 / RFC 0001 §6.1 tenant derivation): per-ResourceLogs tenant derivation + fan-out, flipping RFC0003.3/.4 live. Builds on materialisation (#132).

Design (rule pinned by RFC 0001 §6.1 — no open question)

• receiver::tenant::TenantRule — the operator-configured derivation rule: a single string-valued resource attribute, default key service.name (the OTel-canonical "what application emitted this", mapping onto per-tenant template-tree partitioning [§3.7]). by_attribute covers operator-chosen keys.
• derive → TenantId, or a hand-rolled TenantResolutionError (no thiserror) naming the attribute when it's absent, non-string, or empty — the receiver never invents a tenant the operator hasn't declared.
• materialize::materialize_resource_logs — flattens one ResourceLogs' scope × records under the resolved tenant (built on materialize_record).
• fan_out — derives the tenant once per ResourceLogs, tags every record with it; the miner's per-tenant routing keeps streams separate. If any ResourceLogs fails to resolve, the entire export is rejected (?-propagated before any records are returned — no partial batch). Per-Resource partial rejection is out of scope per RFC 0001 §6.1.

Scenarios (now live)

• .3 — a two-service export fans out to two tenants; body markers prove a record never lands under the wrong tenant.
• .4 — a resolvable + an unresolvable Resource → the whole batch is rejected and the error names service.name; no records accepted.

Plus tenant-module unit tests for derive (default key, missing/non-string/empty → error, custom operator key).

Verification

• cargo test -p ourios-ingester ✓ — RFC0003.3–.10 live; 7 scenarios remain ignored (.1/.2/.11–.15, the transport / WAL-before-ack / concurrency group). No new dependencies.
• cargo fmt --all --check ✓ · cargo clippy --all-targets --all-features -- -D warnings ✓ (workspace)

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

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Run ID: f310e01a-223f-40e9-a040-e88b55977348

📥 Commits

Reviewing files that changed from the base of the PR and between 5ae5435 and d7babf1.

📒 Files selected for processing (6)

• crates/ourios-ingester/src/lib.rs
• crates/ourios-ingester/src/receiver.rs
• crates/ourios-ingester/src/receiver/materialize.rs
• crates/ourios-ingester/src/receiver/tenant.rs
• crates/ourios-ingester/tests/rfc0003_3_tenant_fanout.rs
• crates/ourios-ingester/tests/rfc0003_4_tenant_resolution_failure.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/otlp-receiver-tenant-fanout

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[jensholdgaard]

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[Copilot]

Pull request overview

Implements the RFC 0001 §6.1 tenant-derivation rule and RFC0003.3/.4 behavior in the ingester receiver by deriving a TenantId per ResourceLogs group and fanning out materialized records accordingly, with all-or-nothing rejection when any group fails tenant resolution.

Changes:

• Added receiver::tenant module with TenantRule, TenantResolutionError, and fan_out to derive tenants per ResourceLogs and tag all materialized records.
• Added materialize_resource_logs to materialize all (ScopeLogs, LogRecord) under a single ResourceLogs group for a resolved tenant.
• Flipped RFC0003.3 and RFC0003.4 tests from ignored stubs to live assertions covering fan-out and whole-batch rejection.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/ourios-ingester/tests/rfc0003_4_tenant_resolution_failure.rs	Activates RFC0003.4 test asserting whole-export rejection with missing attribute named.
crates/ourios-ingester/tests/rfc0003_3_tenant_fanout.rs	Activates RFC0003.3 test asserting per-tenant fan-out without cross-contamination.
crates/ourios-ingester/src/receiver/tenant.rs	Introduces tenant derivation rule/error and fan_out implementation plus unit tests.
crates/ourios-ingester/src/receiver/materialize.rs	Adds materialize_resource_logs to materialize all records under one ResourceLogs for a tenant.
crates/ourios-ingester/src/receiver.rs	Wires in tenant module and re-exports tenant + new materialization entrypoints.
crates/ourios-ingester/src/lib.rs	Updates crate-level docs to reflect tenant derivation + fan-out slice is landed.

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