Fix #2541: use UserAgent from RequestContext for the metrics tag

src/main/java/io/stargate/sgv2/jsonapi/metrics/TenantRequestMetricsTagProvider.java

@@ -1,26 +1,24 @@
 package io.stargate.sgv2.jsonapi.metrics;
 
 import static io.stargate.sgv2.jsonapi.metrics.MetricsConstants.UNKNOWN_VALUE;
+import static io.stargate.sgv2.jsonapi.util.StringUtil.isNullOrBlank;
 
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.Tags;
 import io.quarkus.micrometer.runtime.HttpServerMetricsTagsContributor;
 import io.stargate.sgv2.jsonapi.api.request.RequestContext;
+import io.stargate.sgv2.jsonapi.api.request.UserAgent;
 import io.stargate.sgv2.jsonapi.api.v1.metrics.MetricsConfig;
 import io.vertx.core.http.HttpServerRequest;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.enterprise.context.ContextNotActiveException;
 import jakarta.inject.Inject;
 import jakarta.ws.rs.core.HttpHeaders;
-import java.util.regex.Pattern;
 
 /** Tags provider for http request metrics. It provides tenant id and user agent as tags. */
 @ApplicationScoped
 public class TenantRequestMetricsTagProvider implements HttpServerMetricsTagsContributor {
 
-  // split pattern for the user agent, extract only first part of the agent
-  private static final Pattern USER_AGENT_SPLIT = Pattern.compile("[\\s/]");
-
   /** The configuration for metrics. */
   private final MetricsConfig.TenantRequestCounterConfig config;
 
@@ -70,17 +68,16 @@ public Tags contribute(Context context) {
     return tags;
   }
 
+  /** The {@link UserAgent#product()} from the request context will be used if possible */
   private String getUserAgentValue(HttpServerRequest request) {
-    String headerString = request.getHeader(HttpHeaders.USER_AGENT);
-    if (null != headerString && !headerString.isBlank()) {
-      String[] split = USER_AGENT_SPLIT.split(headerString);
-      if (split.length > 0) {
-        return split[0];
-      } else {
-        return headerString;
-      }
-    } else {
-      return UNKNOWN_VALUE;
+
+    String userAgent;
+    try {
+      userAgent = requestContext.userAgent().product();
+    } catch (ContextNotActiveException | IllegalStateException e) {
+      // no request context, so use the full USER_AGENT header
+      userAgent = request.getHeader(HttpHeaders.USER_AGENT);
     }
+    return isNullOrBlank(userAgent) ? UNKNOWN_VALUE : userAgent;
   }
 }

src/test/java/io/stargate/sgv2/jsonapi/metrics/TenantRequestMetricsTagProviderTest.java

@@ -0,0 +1,87 @@
+package io.stargate.sgv2.jsonapi.metrics;
+
+import static io.restassured.RestAssured.given;
+import static io.stargate.sgv2.jsonapi.metrics.MetricsConstants.UNKNOWN_VALUE;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.google.common.collect.ImmutableMap;
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.QuarkusTestProfile;
+import io.quarkus.test.junit.TestProfile;
+import io.restassured.http.ContentType;
+import io.restassured.response.ValidatableResponse;
+import io.stargate.sgv2.jsonapi.api.v1.GeneralResource;
+import io.stargate.sgv2.jsonapi.config.constants.HttpConstants;
+import jakarta.ws.rs.core.HttpHeaders;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+
+/** Tests for the user agent tag {@link TenantRequestMetricsTagProvider} adds to request metrics. */
+@QuarkusTest
+@TestProfile(TenantRequestMetricsTagProviderTest.UserAgentTagProfile.class)
+public class TenantRequestMetricsTagProviderTest {
+
+  private static final String FULL_AGENT = "langflow/1.4.2 langchain/0.3.59 astrapy/2.0.1";
+  private static final String COMMAND = "{\"noSuchCommand\": {}}";
+
+  /** The user agent tag is off by default. */
+  public static class UserAgentTagProfile implements QuarkusTestProfile {
+
+    @Override
+    public boolean disableGlobalTestResources() {
+      return true;
+    }
+
+    @Override
+    public Map<String, String> getConfigOverrides() {
+      return ImmutableMap.of(
+          "stargate.metrics.tenant-request-counter.user-agent-tag-enabled", "true");
+    }
+  }
+
+  @Test
+  public void productWhenRequestContext() {
+    postCommand(FULL_AGENT).statusCode(200);
+    assertUserAgentTag("langflow");
+  }
+
+  @Test
+  public void fullAgentWhenNoRequestContext() {
+    // no token, the request is rejected before the RequestContext is created
+    given()
+        .contentType(ContentType.JSON)
+        .header(HttpHeaders.USER_AGENT, FULL_AGENT)
+        .body(COMMAND)
+        .when()
+        .post(GeneralResource.BASE_PATH)
+        .then()
+        .statusCode(401);
+
+    assertUserAgentTag(FULL_AGENT);
+  }
+
+  @Test
+  public void unknownWhenNoAgent() {
+    postCommand("").statusCode(200);
+    assertUserAgentTag(UNKNOWN_VALUE);
+  }
+
+  private ValidatableResponse postCommand(String userAgent) {
+    return given()
+        .contentType(ContentType.JSON)
+        .header(HttpConstants.AUTHENTICATION_TOKEN_HEADER_NAME, "token")
+        .header(HttpHeaders.USER_AGENT, userAgent)
+        .body(COMMAND)
+        .when()
+        .post(GeneralResource.BASE_PATH)
+        .then();
+  }
+
+  private void assertUserAgentTag(String expected) {
+    String metrics = given().when().get("/metrics").then().statusCode(200).extract().asString();
+
+    assertThat(metrics.lines().filter(line -> line.startsWith("http_server_requests_")).toList())
+        .describedAs("user agent tag for %s", expected)
+        .anyMatch(line -> line.contains("user_agent=\"%s\"".formatted(expected)));
+  }
+}