[io.metrics] Fix MetricsService breaking REST API #10640 (#10644)

* [io.metrics] Fix MetricsService breaking REST API #10640

Signed-off-by: Robert Bach <openhab@mortalsilence.net>

bundles/org.openhab.io.metrics/README.md

@@ -46,7 +46,7 @@ For a start, the following formats are supported:
 ### Prometheus
 
 Once the IO addon is installed, the Prometheus endpoint will be available under:
-_<openhab_host>:8080/metrics/prometheus_ 
+_<openhab_host>:8080/rest/metrics/prometheus_ 
 
 Refer to the [Prometheus](https://prometheus.io/) documentation on how to setup a Prometheus instance and add a scrape configuration. A typical scrape config could look like this (excerpt from `/etc/prometheus/prometheus.yml`):
 
@@ -55,7 +55,7 @@ scrape_configs:
   - job_name: 'openhab'
     scrape_interval: 1m
     scheme: http
-    metrics_path: /metrics/prometheus
+    metrics_path: /rest/metrics/prometheus
     static_configs:
     - targets:
       - 'openhab.local:8080'

bundles/org.openhab.io.metrics/pom.xml

@@ -74,5 +74,11 @@
         </exclusion>
       </exclusions>
     </dependency>
+    <dependency>
+      <groupId>org.openhab.core.bundles</groupId>
+      <artifactId>org.openhab.core.io.rest</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
   </dependencies>
 </project>

bundles/org.openhab.io.metrics/src/main/java/org/openhab/io/metrics/MetricsRestController.java

@@ -12,7 +12,10 @@
  */
 package org.openhab.io.metrics;
 
+import java.util.HashSet;
+import java.util.Map;
 import java.util.Objects;
+import java.util.Set;
 
 import javax.annotation.security.RolesAllowed;
 import javax.ws.rs.GET;
@@ -23,8 +26,14 @@ import javax.ws.rs.core.MediaType;
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.auth.Role;
+import org.openhab.core.config.core.ConfigurableService;
+import org.openhab.core.config.core.Configuration;
 import org.openhab.core.io.monitor.MeterRegistryProvider;
+import org.openhab.core.io.rest.RESTConstants;
+import org.openhab.io.metrics.exporters.InfluxMetricsExporter;
+import org.osgi.service.component.annotations.Activate;
 import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Modified;
 import org.osgi.service.component.annotations.Reference;
 import org.osgi.service.jaxrs.whiteboard.JaxrsWhiteboardConstants;
 import org.osgi.service.jaxrs.whiteboard.propertytypes.JSONRequired;
@@ -43,24 +52,27 @@ import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 /**
- * * The {@link MetricsRestController} class implements the REST endpoints for all pull based monitoring systems.
+ * The {@link MetricsRestController} class implements the REST endpoints for all pull based monitoring systems.
  *
  * @author Robert Bach - Initial contribution
  */
 @Component(immediate = true, service = MetricsRestController.class)
 @JaxrsResource
-@JaxrsApplicationSelect("(" + JaxrsWhiteboardConstants.JAX_RS_NAME + "=" + MetricsService.METRICS_APP_NAME + ")")
+@JaxrsApplicationSelect("(" + JaxrsWhiteboardConstants.JAX_RS_NAME + "=" + RESTConstants.JAX_RS_NAME + ")")
-@Path("")
+@Path(MetricsRestController.PATH_METRICS)
 @JSONRequired
 @RolesAllowed({ Role.USER, Role.ADMIN })
 @Tag(name = MetricsRestController.PATH_METRICS)
 @NonNullByDefault
+@ConfigurableService(category = "io", label = "Metrics service", description_uri = "io:metrics")
 public class MetricsRestController {
     private final Logger logger = LoggerFactory.getLogger(MetricsRestController.class);
     public static final String PATH_METRICS = "metrics";
     private @Nullable CompositeMeterRegistry meterRegistry = null;
     private final PrometheusMeterRegistry prometheusMeterRegistry = new PrometheusMeterRegistry(
             PrometheusConfig.DEFAULT);
+    private final Set<MetricsExporter> metricsExporters = new HashSet<>();
+    private @Nullable MetricsConfiguration config;
 
     @GET
     @Path("/prometheus")
@@ -79,5 +91,29 @@ public class MetricsRestController {
         meterRegistry = meterRegistryProvider.getOHMeterRegistry();
         Objects.requireNonNull(meterRegistry).add(prometheusMeterRegistry);
         logger.debug("Core metrics registry retrieved and Prometheus registry added successfully.");
+        updateMeterRegistry();
+    }
+
+    @Activate
+    protected void activate(Map<@Nullable String, @Nullable Object> configuration) {
+        logger.info("Metrics service activated, serving the following URL(s): /rest/metrics/prometheus");
+        metricsExporters.add(new InfluxMetricsExporter());
+        updateConfig(configuration);
+        updateMeterRegistry();
+    }
+
+    @Modified
+    protected synchronized void modified(Map<@Nullable String, @Nullable Object> configuration) {
+        updateConfig(configuration);
+    }
+
+    private void updateConfig(@Nullable Map<@Nullable String, @Nullable Object> configuration) {
+        this.config = new Configuration(configuration).as(MetricsConfiguration.class);
+        logger.debug("Configuration: {}", this.config);
+        this.metricsExporters.forEach(e -> e.updateExporterState(config));
+    }
+
+    private void updateMeterRegistry() {
+        this.metricsExporters.forEach(e -> e.setMeterRegistry(meterRegistry));
     }
 }

bundles/org.openhab.io.metrics/src/main/java/org/openhab/io/metrics/MetricsService.java

@@ -1,117 +0,0 @@
-/**
- * Copyright (c) 2010-2021 Contributors to the openHAB project
- *
- * See the NOTICE file(s) distributed with this work for additional
- * information.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Public License 2.0 which is available at
- * http://www.eclipse.org/legal/epl-2.0
- *
- * SPDX-License-Identifier: EPL-2.0
- */
-package org.openhab.io.metrics;
-
-import java.util.Dictionary;
-import java.util.HashSet;
-import java.util.Hashtable;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
-
-import javax.ws.rs.core.Application;
-
-import org.eclipse.jdt.annotation.NonNullByDefault;
-import org.eclipse.jdt.annotation.Nullable;
-import org.openhab.core.config.core.ConfigurableService;
-import org.openhab.core.config.core.Configuration;
-import org.openhab.core.io.monitor.MeterRegistryProvider;
-import org.openhab.io.metrics.exporters.InfluxMetricsExporter;
-import org.osgi.framework.BundleContext;
-import org.osgi.framework.FrameworkUtil;
-import org.osgi.framework.ServiceRegistration;
-import org.osgi.service.component.annotations.Activate;
-import org.osgi.service.component.annotations.Component;
-import org.osgi.service.component.annotations.Deactivate;
-import org.osgi.service.component.annotations.Modified;
-import org.osgi.service.component.annotations.Reference;
-import org.osgi.service.jaxrs.whiteboard.JaxrsWhiteboardConstants;
-import org.osgi.service.jaxrs.whiteboard.propertytypes.JaxrsName;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
-
-/**
- * The {@link MetricsService} class implements the central component controlling the different metric endpoints/syncers.
- *
- * @author Robert Bach - Initial contribution
- */
-@NonNullByDefault
-@Component(immediate = true, service = MetricsService.class)
-@ConfigurableService(category = "io", label = "Metrics service", description_uri = "io:metrics")
-public class MetricsService {
-    public static final String METRICS_APP_NAME = "Metrics";
-    public static final String ROOT = "/metrics";
-    private final Logger logger = LoggerFactory.getLogger(MetricsService.class);
-    private @Nullable ServiceRegistration<Application> restService = null;
-    private @Nullable MetricsConfiguration config;
-    @Reference
-    protected @NonNullByDefault({}) MetricsRestController metrics;
-    private Set<MetricsExporter> metricsExporters = new HashSet<>();
-    private @Nullable CompositeMeterRegistry meterRegistry = null;
-
-    @Activate
-    protected void activate(Map<@Nullable String, @Nullable Object> configuration) {
-        MetricsRestApplication app = new MetricsRestApplication();
-        BundleContext context = FrameworkUtil.getBundle(getClass()).getBundleContext();
-        restService = context.registerService(Application.class, app, getServiceProperties());
-        logger.info("Metrics service available under {}.", ROOT);
-        metricsExporters.add(new InfluxMetricsExporter());
-        updateConfig(configuration);
-        updateMeterRegistry();
-    }
-
-    @Modified
-    protected synchronized void modified(Map<@Nullable String, @Nullable Object> configuration) {
-        updateConfig(configuration);
-    }
-
-    @Deactivate
-    protected void deactivate() {
-        if (restService != null) {
-            Objects.requireNonNull(restService).unregister();
-        }
-    }
-
-    Dictionary<@Nullable String, @Nullable String> getServiceProperties() {
-        Dictionary<@Nullable String, @Nullable String> dict = new Hashtable<>();
-        dict.put(JaxrsWhiteboardConstants.JAX_RS_APPLICATION_BASE, ROOT);
-        return dict;
-    }
-
-    @JaxrsName(METRICS_APP_NAME)
-    private class MetricsRestApplication extends Application {
-        @NonNullByDefault({})
-        @Override
-        public Set<Object> getSingletons() {
-            return Set.of(metrics);
-        }
-    }
-
-    @Reference
-    public void setMeterRegistryProvider(MeterRegistryProvider meterRegistryProvider) {
-        meterRegistry = meterRegistryProvider.getOHMeterRegistry();
-        updateMeterRegistry();
-    }
-
-    private void updateConfig(@Nullable Map<@Nullable String, @Nullable Object> configuration) {
-        this.config = new Configuration(configuration).as(MetricsConfiguration.class);
-        logger.debug("Configuration: {}", this.config);
-        this.metricsExporters.forEach(e -> e.updateExporterState(config));
-    }
-
-    private void updateMeterRegistry() {
-        this.metricsExporters.forEach(e -> e.setMeterRegistry(meterRegistry));
-    }
-}