Add PrometheusSeriesResponseListener for series endpoint by felixbarny · Pull Request #144492 · elastic/elasticsearch

felixbarny · 2026-03-18T13:50:06Z

Implements an ActionListener that converts ESQL query results into a Prometheus-compatible series response, including label name/value extraction and proto serialization.

Also adds ESQL compile-time dependencies to the prometheus plugin.

Stack:

elasticsearchmachine · 2026-03-18T13:50:34Z

Pinging @elastic/es-storage-engine (Team:StorageEngine)

Extend the prometheus plugin with compile-time dependencies on x-pack-esql, x-pack-esql-core, and esql:compute so that the series endpoint can build and execute ESQL logical plans.

Implements an ActionListener that converts ESQL query results into a Prometheus-compatible series response, including label name/value extraction and proto serialization.

These tests exercise PrometheusSeriesRestAction.parseQueryString which doesn't exist on this branch. Move them to the rest action PR.

.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java

…sets

metric_name cannot be null and empty dimensions is not legal, so the test now verifies that the existing assertion in buildLabelMap is tripped rather than expecting a valid empty label map.

sidosera · 2026-03-24T12:10:13Z

.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java

+     * Prometheus HTTP API error type strings, as defined in the Prometheus source:
+     * https://github.com/prometheus/prometheus/blob/main/web/api/v1/api.go
+     */
+    private static final String ERROR_TYPE_EXECUTION = "execution";


I've consolidated the error handling with PrometheusQueryRangeResponseListener now and created a shared PrometheusErrorResponse helper.

.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java

sidosera · 2026-03-24T12:19:26Z

.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java

+        try {
+            List<Map<String, String>> seriesList = extractSeries(response);
+            channel.sendResponse(buildSuccessResponse(seriesList));
+        } catch (Exception e) {


Can we reuse org/elasticsearch/action/ActionListener.java:250 ?

sidosera · 2026-03-24T12:30:47Z

.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java

+        sendError(e);
+    }
+
+    // -------------------------------------------------------------------------


nit: I can we use this comment pattern around tests but not sure how consistent it is with the rest of the codebase. Just flagging.

sidosera

Left a few minor comments; otherwise looks good.

One broader question. What’s the intended home for response format conversion rest layer or compute engine. Any particular reason we chose current approach?

…ponse-listener

- Convert error type string constants to a private enum - Rename buildSuccessResponse -> replaySuccess (void, non-static, sends response directly) - Rename sendError -> replayError - Remove separator comment style - Add imports for XContentParser and XContentParserConfiguration (replacing FQNs)

Both PrometheusQueryRangeResponseListener and PrometheusSeriesResponseListener shared duplicate error type mapping and error JSON construction logic. Extract to a single PrometheusErrorResponse class with: - send(channel, e, logger): builds and sends the error response with fallback - build(status, message): constructs the error JSON builder - mapErrorType(status): maps HTTP status to Prometheus error type string The series listener now uses ExceptionsHelper.status(e) for status resolution (consistent with the range listener) instead of manual instanceof checks.

) Implements an ActionListener that converts ESQL query results into a Prometheus-compatible series response, including label name/value extraction and JSON serialization.

felixbarny added >non-issue :StorageEngine/TSDB You know, for Metrics labels Mar 18, 2026

felixbarny self-assigned this Mar 18, 2026

elasticsearchmachine added Team:StorageEngine external-contributor Pull request authored by a developer outside the Elasticsearch team labels Mar 18, 2026

This was referenced Mar 18, 2026

Add PrometheusSeriesRestAction for /_prometheus/api/v1/series endpoint #144494

Merged

Add PrometheusSeriesPlanBuilder for series endpoint #144493

Merged

felixbarny changed the base branch from promql-query-range-parsed-statement to main March 18, 2026 13:52

felixbarny added 2 commits March 18, 2026 14:53

Add esql and esql-core compile dependencies to prometheus plugin

fd2c7c6

Extend the prometheus plugin with compile-time dependencies on x-pack-esql, x-pack-esql-core, and esql:compute so that the series endpoint can build and execute ESQL logical plans.

Add PrometheusSeriesResponseListener for series endpoint

0325a05

Implements an ActionListener that converts ESQL query results into a Prometheus-compatible series response, including label name/value extraction and proto serialization.

felixbarny force-pushed the prometheus-series-response-listener branch from 029ea1e to 0325a05 Compare March 18, 2026 13:54

felixbarny added the v9.4.0 label Mar 18, 2026

Move parseQueryString tests out of PrometheusSeriesResponseListenerTests

0b5e488

These tests exercise PrometheusSeriesRestAction.parseQueryString which doesn't exist on this branch. Move them to the rest action PR.

felixbarny mentioned this pull request Mar 18, 2026

Add RequestParams to handle repeated query parameters #144506

Merged

felixbarny requested a review from kkrik-es March 23, 2026 08:01

Merge branch 'main' into prometheus-series-response-listener

a0f0bc2

kkrik-es reviewed Mar 23, 2026

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.../src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesResponseListener.java Show resolved Hide resolved

kkrik-es approved these changes Mar 23, 2026

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felixbarny and others added 3 commits March 23, 2026 18:54

[Prometheus] Identify TsInfo columns by name instead of hardcoded off…

28fa504

…sets

Merge branch 'main' into prometheus-series-response-listener

bb339a8

[CI] Auto commit changes from spotless

2c2b137

felixbarny enabled auto-merge (squash) March 23, 2026 18:12

[Prometheus] Fix testBuildLabelMapNullMetricName to assert illegal state

fa01411

metric_name cannot be null and empty dimensions is not legal, so the test now verifies that the existing assertion in buildLabelMap is tripped rather than expecting a valid empty label map.