metrics: parse Prometheus text exposition with best practices#1611
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naoNao89 wants to merge 1 commit into
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metrics: parse Prometheus text exposition with best practices#1611naoNao89 wants to merge 1 commit into
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- Prefer parsed sample timestamps over fallback - Preserve HELP as description; keep unsupported families as errors (for now) - Remove gauge normalization in tests; only ensure trailing newline - Pin openmetrics-parser to 0.4.4 (latest) Refs: torrust#1582
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@naoNao89 this looks much better and cleaner :) |
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Superseded by #1729 |
josecelano
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May 5, 2026
19f98d0 refactor(metrics): implement proposals 9-12 in prometheus pipeline (Jose Celano) e2fa3fc docs(metrics): add follow-up refactor proposals 9-12 (Jose Celano) bf76972 refactor(metrics): implement proposal 8 — normalize-parse-convert pipeline (Jose Celano) 0ccddc7 refactor(metrics): use From conversions for collection errors (Jose Celano) d1f219b refactor(metrics): parse_prometheus_timestamp returns Option (Jose Celano) 43b4c57 refactor(metrics): use Cow for input normalization in from_prometheus (Jose Celano) 9de6444 refactor(metrics): extract description_from_help helper (Jose Celano) 04b0d74 refactor(metrics): add MetricDescription From conversions (Jose Celano) 3e91f69 refactor(metrics): extract is_whole_u64_representable predicate (Jose Celano) bbedebd refactor(metrics): extract parse_family_samples via FromPrometheusValue trait (Jose Celano) ffa6c27 docs(metrics): add refactoring proposals for metric_collection/prometheus.rs (Jose Celano) 886761f test(metrics): kill surviving mutants in remaining files (Jose Celano) 0140113 test(metrics): kill surviving mutants in label/set.rs (Jose Celano) 2bb5610 test(metrics): kill surviving mutants in sample_collection.rs and sample.rs (Jose Celano) 4644ec8 test(metrics): kill surviving mutants in counter.rs and gauge.rs (Jose Celano) 333e124 test(metrics): kill surviving mutants in metric_collection/mod.rs (Jose Celano) a6b61c7 test(metrics): kill surviving mutants in metric_collection/prometheus.rs (Jose Celano) 92965d3 docs(metrics): add mutation testing plan for the metrics package (Jose Celano) b8a131d test(metrics): add tests to close llvm-cov coverage gaps (Jose Celano) 8b38a65 docs(metrics): add unit test coverage improvement plan with llvm-cov baseline (Jose Celano) 7ba33c2 refactor(metrics): extract Prometheus impls into metric_collection/prometheus.rs (Jose Celano) f85911e refactor(metrics): extract JSON serde impls into metric_collection/serde.rs (Jose Celano) 9ca54dd refactor(metrics): extract MetricKindCollection into kind_collection.rs (Jose Celano) 15cdb7e refactor(metrics): extract Error into metric_collection/error.rs (Jose Celano) c3c42a1 docs(metrics): add refactor plan for metric_collection module split (Jose Celano) 9b3277e fix(metrics): address Copilot PR review feedback (Jose Celano) 94c53b9 refactor(metrics): extract Prometheus deserialization helpers (Jose Celano) 25f6eb3 feat(metrics): add Prometheus text format deserialization (naoNao89) 014f517 docs(metrics): add issue spec for Prometheus deserialization (#1582) (Jose Celano) Pull request description: ## Summary Adds deserialization from Prometheus exposition text format to `MetricCollection`, completing the serialization ↔ deserialization symmetry alongside the existing JSON and `to_prometheus()` paths. Closes #1582 --- ## What changed ### `packages/metrics/src/prometheus.rs` - New `PrometheusDeserializable` trait (mirrors `PrometheusSerializable`) - New `PrometheusDeserializationError` enum with fine-grained variants: - `ParseError` — syntax error in the input text - `UnsupportedType` — known but not yet supported type (Histogram, Summary, …) - `UnknownType` — unrecognised metric type - `ValueMismatch` — value type does not match the declared metric type - `UnknownValue` — `PrometheusValue::Unknown` sample (no silent zero-returns) - `LabelConversion` — label name/value conversion failure - `CollectionError` — structural error assembling the `MetricCollection` ### `packages/metrics/src/label/set.rs` - `TryFrom<openmetrics_parser::LabelSet<'_>> for LabelSet` — replaces ad-hoc inline label conversion ### `packages/metrics/src/metric_collection/mod.rs` - Private `parse_prometheus_timestamp(t: f64, fallback) -> DurationSinceUnixEpoch` — eliminates the duplicated timestamp-parsing block - `impl PrometheusDeserializable for MetricCollection` — parses Counter and Gauge families; uses `openmetrics-parser 0.4.4` ### `packages/metrics/Cargo.toml` - Added `openmetrics-parser = "0.4.4"` --- ## Tests - Timestamp helper: 8 edge-case unit tests (negative, NaN, ±Inf, nanosecond-boundary overflow, zero) - `TryFrom` for `LabelSet`: 3 unit tests (empty conversion, round-trip, empty-name error) - `MetricCollection`: round-trip serialize → deserialize, error-path tests for unsupported and malformed input - **222 tests pass**, 0 failed --- ## Prior art This is a clean re-implementation based on PR #1611 by @naoNao89, incorporating all maintainer feedback that was pending on that PR. @naoNao89 is preserved as the commit author. ACKs for top commit: josecelano: ACK 19f98d0 Tree-SHA512: f3aee3e168e02da7dd4aa4dbd25af5ea723b9aacf24259ce9b2ac7d1ced66936e10ea41dcfccacaece502e8533120cd507617f827186dea44ee7ffda68356717
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Refs: #1582