Initialize metrics lazily (#10133)

* Initialize metrics lazily

Prepare for using non-default CollectorRegistry for Neo4j plugin setup.

* Register algo metrics in registry (also non-default)

Co-authored-by: Max Kießling <max.kiessling@neo4j.com>

* Improve error details for flaky test

---------

Co-authored-by: Max Kießling <max.kiessling@neo4j.com>

Author: FlorentinD

neo4j-settings/src/main/java/org/neo4j/gds/settings/GdsMetricsSettings.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.settings;
+
+import org.neo4j.annotations.service.ServiceProvider;
+import org.neo4j.configuration.Description;
+import org.neo4j.configuration.SettingImpl;
+import org.neo4j.configuration.SettingsDeclaration;
+import org.neo4j.graphdb.config.Setting;
+
+import static org.neo4j.configuration.SettingValueParsers.BOOL;
+
+@ServiceProvider
+public class GdsMetricsSettings implements SettingsDeclaration {
+
+    // Replacement for the prometheus server from GDS (used for Sessions)
+    @Description("Use GDS-only prometeheus server instead of relying on DBMS")
+    public static final Setting<Boolean> gds_metrics_server_enabled = SettingImpl.newBuilder(
+            "internal.gds.custom_metrics_server", BOOL, Boolean.FALSE)
+        .immutable()
+        .internal()
+        .build();
+
+}

neo4j-settings/src/main/java/org/neo4j/gds/settings/GdsSettings.java

@@ -34,4 +34,8 @@ public static Setting<Path> exportLocation() {
     public static Setting<Boolean> validateUsingMaxMemoryEstimation() {
         return MemoryEstimationSettings.validate_using_max_memory_estimation;
     }
+
+    public static Setting<Boolean> useGdsMetricsServer() {
+        return GdsMetricsSettings.gds_metrics_server_enabled;
+    }
 }