Prometheus labels/series APIs: support multiple match[] selectors

x-pack/plugin/prometheus/src/javaRestTest/java/org/elasticsearch/xpack/prometheus/PrometheusLabelValuesRestIT.java

@@ -12,6 +12,7 @@
 import io.netty.handler.codec.compression.Snappy;
 
 import org.apache.http.HttpHeaders;
+import org.apache.http.client.utils.URIBuilder;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
 import org.elasticsearch.client.Request;
@@ -30,6 +31,7 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasItem;
@@ -135,6 +137,25 @@ public void testGetWithMatchSelectorFiltersValues() throws Exception {
         assertThat(values, not(hasItem("other_job")));
     }
 
+    public void testGetWithMultipleMatchSelectorsReturnsCombinedValues() throws Exception {
+        writeMetric("multi_selector_metric_a", Map.of("job", "multi_job_a"));
+        writeMetric("multi_selector_metric_b", Map.of("job", "multi_job_b"));
+        writeMetric("multi_selector_metric_c", Map.of("job", "multi_job_c")); // must not appear in results
+
+        // Use URIBuilder to send two match[] selectors in a single request, working around the
+        // test client's single-value-per-key restriction on Request.addParameter.
+        Request request = new Request(
+            "GET",
+            new URIBuilder("/_prometheus/api/v1/label/job/values").addParameter("match[]", "multi_selector_metric_a")
+                .addParameter("match[]", "multi_selector_metric_b")
+                .build()
+                .toString()
+        );
+        List<String> values = labelValuesData(client().performRequest(request));
+
+        assertThat(values, containsInAnyOrder("multi_job_a", "multi_job_b"));
+    }
+
     public void testGetValuesAreSorted() throws Exception {
         writeMetric("sorted_gauge", Map.of("job", "zebra"));
         writeMetric("sorted_gauge", Map.of("job", "alpha"));

x-pack/plugin/prometheus/src/javaRestTest/java/org/elasticsearch/xpack/prometheus/PrometheusLabelsRestIT.java

@@ -12,6 +12,7 @@
 import io.netty.handler.codec.compression.Snappy;
 
 import org.apache.http.HttpHeaders;
+import org.apache.http.client.utils.URIBuilder;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
 import org.elasticsearch.client.Request;
@@ -135,6 +136,26 @@ public void testGetWithMatchSelectorFiltersToMatchingLabels() throws Exception {
         assertThat(data, hasItem("unique_label"));
     }
 
+    @SuppressWarnings("unchecked")
+    public void testGetWithMultipleMatchSelectorsReturnsCombinedLabels() throws Exception {
+        writeMetric("multi_labels_metric_a", Map.of("label_only_in_a", "value_a"));
+        writeMetric("multi_labels_metric_b", Map.of("label_only_in_b", "value_b"));
+        writeMetric("multi_labels_metric_c", Map.of("label_only_in_c", "value_c")); // must not appear in results
+
+        // Use URIBuilder to send two match[] selectors in a single request, working around the
+        // test client's single-value-per-key restriction on Request.addParameter.
+        Request request = new Request(
+            "GET",
+            new URIBuilder("/_prometheus/api/v1/labels").addParameter("match[]", "multi_labels_metric_a")
+                .addParameter("match[]", "multi_labels_metric_b")
+                .build()
+                .toString()
+        );
+        List<String> data = (List<String>) entityAsMap(client().performRequest(request)).get("data");
+
+        assertThat(data, containsInAnyOrder("__name__", "label_only_in_a", "label_only_in_b"));
+    }
+
     /** Builds a labels request with optional {@code match[]} parameters. */
     private static Request labelsRequest(String... matchers) {
         Request request = new Request("GET", "/_prometheus/api/v1/labels");

x-pack/plugin/prometheus/src/javaRestTest/java/org/elasticsearch/xpack/prometheus/PrometheusSeriesRestIT.java

@@ -12,6 +12,7 @@
 import io.netty.handler.codec.compression.Snappy;
 
 import org.apache.http.HttpHeaders;
+import org.apache.http.client.utils.URIBuilder;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
 import org.apache.http.util.EntityUtils;
@@ -31,6 +32,7 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasSize;
@@ -143,12 +145,28 @@ public void testSeriesWithIndexPattern() throws Exception {
         assertThat(data.getFirst().get("__name__"), equalTo("test_gauge_idx"));
     }
 
+    public void testGetWithMultipleMatchSelectorsReturnsCombinedSeries() throws Exception {
+        writeMetric("multi_series_selector_a", Map.of("job", "job_a"));
+        writeMetric("multi_series_selector_b", Map.of("job", "job_b"));
+        writeMetric("multi_series_selector_c", Map.of("job", "job_c")); // must not appear in results
+
+        // Use URIBuilder to send two match[] selectors in a single request, working around the
+        // test client's single-value-per-key restriction on Request.addParameter.
+        Request request = new Request(
+            "GET",
+            new URIBuilder("/_prometheus/api/v1/series").addParameter("match[]", "multi_series_selector_a")
+                .addParameter("match[]", "multi_series_selector_b")
+                .build()
+                .toString()
+        );
+        List<Map<String, Object>> data = seriesData(client().performRequest(request));
+
+        List<String> names = data.stream().map(s -> (String) s.get("__name__")).toList();
+        assertThat(names, containsInAnyOrder("multi_series_selector_a", "multi_series_selector_b"));
+    }
+
     // Helpers
 
-    /**
-     * Builds a series request with a single {@code match[]} parameter.
-     * TODO: support multiple {@code match[]} values once multi-value query param support lands.
-     */
     private static Request seriesRequest(String matcher) {
         return seriesRequest(null, matcher);
     }

x-pack/plugin/prometheus/src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusLabelValuesRestAction.java

@@ -9,6 +9,7 @@
 
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RequestParams;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
@@ -73,9 +74,10 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
         String labelName = PrometheusLabelNameUtils.decodeLabelName(rawName);
         String index = request.param(INDEX_PARAM, "*");
 
-        // TODO: support multiple match[] selectors once multi-value param support is added
-        String matchSelector = request.param(MATCH_PARAM);
-        List<String> matchSelectors = matchSelector != null ? List.of(matchSelector) : List.of();
+        // Consume the parameter; re-parse from the raw URI to handle repeated match[] params,
+        // since request processing currently keeps only the last value for repeated parameters.
+        request.repeatedParamAsList(MATCH_PARAM);
+        List<String> matchSelectors = RequestParams.fromUri(request.uri()).getAll(MATCH_PARAM);
 
         // Time range
         String endParam = request.param(END_PARAM);

x-pack/plugin/prometheus/src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusLabelsRestAction.java

@@ -9,6 +9,7 @@
 
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RequestParams;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
@@ -59,8 +60,10 @@ public List<Route> routes() {
 
     @Override
     protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
-        String matchParam = request.param(MATCH_PARAM);
-        List<String> matchSelectors = matchParam != null ? List.of(matchParam) : List.of();
+        // Consume the parameter; re-parse from the raw URI to handle repeated match[] params,
+        // since request processing currently keeps only the last value for repeated parameters.
+        request.repeatedParamAsList(MATCH_PARAM);
+        List<String> matchSelectors = RequestParams.fromUri(request.uri()).getAll(MATCH_PARAM);
 
         // Time range
         String endParam = request.param(END_PARAM);

x-pack/plugin/prometheus/src/main/java/org/elasticsearch/xpack/prometheus/rest/PrometheusSeriesRestAction.java

@@ -9,6 +9,7 @@
 
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RequestParams;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
@@ -57,12 +58,13 @@ public List<Route> routes() {
 
     @Override
     protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
-        // TODO: support multiple match[] values once multi-value query param support lands
-        String matchSelector = request.param(MATCH_PARAM);
-        if (matchSelector == null) {
+        // Consume the parameter; re-parse from the raw URI to handle repeated match[] params,
+        // since request processing currently keeps only the last value for repeated parameters.
+        request.repeatedParamAsList(MATCH_PARAM);
+        List<String> matchSelectors = RequestParams.fromUri(request.uri()).getAll(MATCH_PARAM);
+        if (matchSelectors.isEmpty()) {
             throw new IllegalArgumentException("At least one [match[]] selector is required");
         }
-        List<String> matchSelectors = List.of(matchSelector);
 
         // Time range
         String endParam = request.param(END_PARAM);