sarangv opened a new pull request, #19030: URL: https://github.com/apache/druid/pull/19030
Fixes [19021](https://github.com/apache/druid/issues/19021). ### Description `LoggingEmitter` can restrict which metrics are written to the log. When this behavior is turned on, only `ServiceMetricEvent` metrics that appear in a configured permitted set are emitted; alerts and other non-metric events are never dropped. When the feature is off, the emitter behaves as before (all events logged). #### Runtime properties - **`druid.emitter.logging.shouldFilterMetrics`** (default `false`): If `true`, logging is limited to metrics named in the permitted set. If `false`, every event is logged. - **`druid.emitter.logging.allowedMetricsPath`** (optional): File path for the permitted-metrics definition. Omitted or empty → the in-JAR resource `defaultMetrics.json` is used. If a path is given but the file does not exist, a warning is logged and the in-JAR resource is used instead (startup continues; operators can spot the warning). #### Permitted-metrics file shape The file must be a **JSON object** whose keys are metric names; values are placeholders (e.g. `[]`), e.g. `{"query/time": [], "query/bytes": []}`. This shape matches other emitter default configs (e.g. Prometheus) and leaves room for per-metric metadata later. On invalid content, operators see: *"Allowed metrics file must be a JSON object with metric names as keys"*. #### Rationale - **DruidException**: Errors use `DruidException.forPersona(Persona.OPERATOR)` with `NOT_FOUND` (default resource absent) and `RUNTIME_FAILURE` (parse/read failure), matching the project’s guidance for operator-facing failures. - **Missing custom file**: Rather than failing startup, the code logs a WARN and uses the in-JAR default so a wrong path does not prevent the process from starting; the log still exposes the mistake. - **Object format**: A key-value object was chosen over a JSON array so the schema can later carry extra fields per metric without a breaking change. - **Emitters.java**: The two new keys are written into the legacy logging map only when the matching property exists, preserving Java defaults and avoiding odd empty-string behavior. - **No set when off**: With filtering disabled, `allowedMetrics` stays `null`; no extra collection is created. Contains checks stay O(1). #### Release note Operators can limit which metrics the logging emitter writes by setting `druid.emitter.logging.shouldFilterMetrics=true` and, if desired, `druid.emitter.logging.allowedMetricsPath` to a JSON object file (keys = metric names). A missing custom file results in a warning and use of the bundled `defaultMetrics.json`. Alerts and other non-metric events are always logged. <hr> ##### Key changed/added classes in this PR - `LoggingEmitter` – load permitted set (classpath or file; use default if file missing), apply in `emit()`, DruidException on bad/missing config - `LoggingEmitterConfig` – `shouldFilterMetrics`, `allowedMetricsPath` plus Javadoc - `Emitters` – map the new keys from legacy properties only when set - `processing/src/main/resources/defaultMetrics.json` – in-JAR permitted set (object form) - `processing/src/test/resources/defaultMetrics.json` – test resource - `LoggingEmitterTest` – seven cases: feature off, default resource, custom file, missing file uses default, non-metrics pass through, empty set, path ignored when off; `@After` tearDown for close - `LoggingEmitterConfigTest` – new config fields covered for defaults and legacy mapping <hr> This PR has: - [x] been self-reviewed. - [ ] added documentation for new or modified features or behaviors. - [x] a release note entry in the PR description. - [x] added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links. - [ ] added or updated version, license, or notice information in [licenses.yaml](https://github.com/apache/druid/blob/master/dev/license.md) - [x] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader. - [x] added unit tests or modified existing tests to cover new code paths, ensuring the threshold for [code coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md) is met. - [ ] added integration tests. - [x] been tested in a test Druid cluster. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
