[io.metrics] initial contribution (#9890)

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

CODEOWNERS

@@ -313,6 +313,7 @@
 /bundles/org.openhab.io.homekit/ @beowulfe @yfre
 /bundles/org.openhab.io.hueemulation/ @davidgraeff @digitaldan
 /bundles/org.openhab.io.imperihome/ @pdegeus
+/bundles/org.openhab.io.metrics/ @pravussum
 /bundles/org.openhab.io.neeo/ @tmrobert8
 /bundles/org.openhab.io.openhabcloud/ @kaikreuzer
 /bundles/org.openhab.persistence.dynamodb/ @ssalonen

bom/openhab-addons/pom.xml

@@ -1536,6 +1536,11 @@
       <artifactId>org.openhab.io.imperihome</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.openhab.addons.bundles</groupId>
+      <artifactId>org.openhab.io.metrics</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>org.openhab.addons.bundles</groupId>
       <artifactId>org.openhab.io.neeo</artifactId>

bundles/org.openhab.io.metrics/NOTICE

@@ -0,0 +1,13 @@
+This content is produced and maintained by the openHAB project.
+
+* Project home: https://www.openhab.org
+
+== Declared Project Licenses
+
+This program and the accompanying materials are made available under the terms
+of the Eclipse Public License 2.0 which is available at
+https://www.eclipse.org/legal/epl-2.0/.
+
+== Source Code
+
+https://github.com/openhab/openhab-addons

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

@@ -0,0 +1,99 @@
+# Metrics service
+
+The metrics service provides 
+
+* an additional REST endpoint to retrieve openHAB core metrics from. This can be used as scrape target for pull-based monitoring systems like [Prometheus](https://prometheus.io/).
+* optionally configurable services to export openHAB core metrics to push-based monitoring systems like [InfluxDB](https://www.influxdata.com/). 
+
+## Precondition
+
+The openHAB core metrics must be available (OH version >= 3.1.0 M2 is necessary).
+
+## Provided metrics
+
+Currently the following metrics are provided: 
+
+- openHAB events counts (per topic)
+- openHAB bundle states
+- openHAB thing states
+- openHAB rule runs (per rule)
+- openHAB threadpool stats (per scheduler)
+- JVM stats including metrics of
+    - class loader
+    - memory
+    - GarbageCollector
+    - OS (system load, CPU)
+    - thread metrics
+
+## Configuration
+
+The configuration for the metrics service is available in the openHAB UI under Settings | Other Services | Metrics service.
+Support for pull-based monitoring systems (e. g. Prometheus) is always enabled, since it doesn't imply any significant overhead when not used.
+Support for push-based monitoring systems (e. g. InfluxDB) have to be enabled separately. 
+
+The following configuration parameters can be set:
+
+|Config param|Description|Default value|
+|--|--|--|
+|influxMetricsEnabled|Enable the Influx (www.influxdata.com) metrics. Further configuration of the InfluxDB instance necessary.|false|
+
+Refer to the corresponding monitoring system sections for monitoring system specific configuration parameters.  
+
+### Supported monitoring systems
+
+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_ 
+
+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`):
+
+````shell
+scrape_configs:
+  - job_name: 'openhab'
+    scrape_interval: 1m
+    scheme: http
+    metrics_path: /metrics/prometheus
+    static_configs:
+    - targets:
+      - 'openhab.local:8080'
+````
+
+Replace `openhab.local` by the openhab host.   
+
+#### Available configuration parameters
+
+There are no Prometheus specific configuration paramters.
+
+### InfluxDB
+
+The InfluxDB exporter service will start as soon as the _influxMetricsEnabled_ configuration parameter is set to true.
+
+#### Available configuration parameters
+
+|Config param|Description|Default value|
+|--|--|--|
+|influxURL|The URL of the InfluxDB instance. Defaults to http://localhost:8086|http://localhost:8086|
+|influxDB|The name of the database to use. Defaults to "openhab".|openhab|
+|influxUsername|InfluxDB user name|n/a|
+|influxPassword|The InfluxDB password (no default).|n/a|
+|influxUpdateIntervalInSeconds|Controls how often metrics are exported to InfluxDB (in seconds). Defaults to 300|300|
+
+## Additional metric formats
+
+The metrics service was implemented using [Micrometer](https://micrometer.io), which supports a number of [monitoring systems](https://micrometer.io/docs) 
+It should be possible to add any of these, especially the ones using a pull mechanism ("scraping") like Prometheus does.     
+
+## Grafana
+
+You can now visualize the results in Grafana. Micrometer provides a public [Grafana dashboard here](https://grafana.com/grafana/dashboards/4701). 
+I adapted it a little bit to include the openHAB metrics. You can download it here [Dashboard](docs/dashboard.json). 
+This has been tested with Prometheus - for other monitoring systems adaptions to the dashboard might be necessary.  
+
+Here are some screenshots: 
+
+![Grafana (1)](docs/grafana-1.png)
+![Grafana (2)](docs/grafana-2.png)
+![Grafana (3)](docs/grafana-3.png)

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

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.openhab.addons.bundles</groupId>
+    <artifactId>org.openhab.addons.reactor.bundles</artifactId>
+    <version>3.1.0-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>org.openhab.io.metrics</artifactId>
+
+  <name>openHAB Add-ons :: Bundles :: IO :: Metrics Service</name>
+
+  <properties>
+    <micrometer.version>1.6.3</micrometer.version>
+    <bnd.importpackage>io.micrometer.core.*;resolution:=optional;ch.qos.logback.*;resolution:=optional,com.codahale.*;resolution:=optional,com.github.benmanes.caffeine.*;resolution:=optional;com.mongodb.*;resolution:=optional,com.netflix.*;resolution:=optional;com.sun.management.*;resolution:=optional,io.netty.*;resolution:=optional;javax.annotation.meta.*;resolution:=optional,javax.cache.*;resolution:=optional,javax.persistence.*;resolution:=optional,net.sf.ehcache.*;resolution:=optional,okhttp3.*;resolution:=optional,org.apache.catalina.*;resolution:=optional,org.apache.http.*;resolution:=optional,org.apache.kafka.*;resolution:=optional,org.apache.logging.*;resolution:=optional,org.aspectj.*;resolution:=optional,org.hibernate.*;resolution:=optional,org.jooq.*;resolution:=optional,org.reactivestreams.*;resolution:=optional,reactor.*;resolution:=optional,rx.*;resolution:=optional</bnd.importpackage>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-core</artifactId>
+      <version>${micrometer.version}</version>
+      <scope>provided</scope><!-- is already included in the openhab.core.io.monitor dependency -->
+    </dependency>
+    <dependency>
+      <groupId>org.hdrhistogram</groupId>
+      <artifactId>HdrHistogram</artifactId>
+      <version>2.1.12</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.latencyutils</groupId>
+      <artifactId>LatencyUtils</artifactId>
+      <version>2.0.3</version>
+      <scope>compile</scope>
+      <exclusions>
+        <exclusion>
+          <artifactId>HdrHistogram</artifactId>
+          <groupId>org.hdrhistogram</groupId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-prometheus</artifactId>
+      <version>${micrometer.version}</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.prometheus</groupId>
+      <artifactId>simpleclient_common</artifactId>
+      <version>0.9.0</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.prometheus</groupId>
+      <artifactId>simpleclient</artifactId>
+      <version>0.9.0</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-influx</artifactId>
+      <version>${micrometer.version}</version>
+      <scope>compile</scope>
+      <exclusions>
+        <exclusion>
+          <artifactId>slf4j-api</artifactId>
+          <groupId>org.slf4j</groupId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+  </dependencies>
+</project>

bundles/org.openhab.io.metrics/src/main/feature/feature.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<features name="org.openhab.io.metrics-${project.version}" xmlns="http://karaf.apache.org/xmlns/features/v1.4.0">
+	<repository>mvn:org.openhab.core.features.karaf/org.openhab.core.features.karaf.openhab-core/${ohc.version}/xml/features</repository>
+
+	<feature name="openhab-misc-metrics" description="Metrics Service" version="${project.version}">
+		<feature>openhab-runtime-base</feature>
+		<feature>openhab-core-model-item</feature>
+		<feature>openhab-core-base</feature>
+		<bundle start-level="80">mvn:org.openhab.addons.bundles/org.openhab.io.metrics/${project.version}</bundle>
+	</feature>
+</features>

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

@@ -0,0 +1,39 @@
+/**
+ * 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 org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
+/**
+ * The {@link MetricsConfiguration} class holds the configuration for the metrics service
+ *
+ * @author Robert Bach - Initial contribution
+ */
+@NonNullByDefault
+public class MetricsConfiguration {
+    public boolean influxMetricsEnabled = false;
+    public String influxURL = "http://localhost:8086";
+    public String influxDB = "openhab";
+    public @Nullable String influxPassword = null;
+    public @Nullable String influxUsername = null;
+    public Integer influxUpdateIntervalInSeconds = 300;
+
+    @Override
+    public String toString() {
+        return "MetricsConfiguration{" + "influxMetricsEnabled=" + influxMetricsEnabled + ", influxURL='" + influxURL
+                + '\'' + ", influxDB='" + influxDB + '\'' + ", influxPassword='" + influxPassword + '\''
+                + ", influxUsername='" + influxUsername + '\'' + ", influxUpdateIntervalInSeconds="
+                + influxUpdateIntervalInSeconds + '}';
+    }
+}

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

@@ -0,0 +1,68 @@
+/**
+ * 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.Objects;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+
+/**
+ * {@link MetricsExporter} provides the interface for components exporting metrics to push based monitoring systems.
+ *
+ * @author Robert Bach - Initial contribution
+ */
+@NonNullByDefault
+public abstract class MetricsExporter {
+
+    private final Logger logger = LoggerFactory.getLogger(MetricsExporter.class);
+    private boolean active = false;
+    protected @Nullable CompositeMeterRegistry meterRegistry = null;
+    protected @Nullable MetricsConfiguration config = null;
+
+    protected abstract void start(CompositeMeterRegistry meterRegistry, MetricsConfiguration metricsConfiguration);
+
+    protected abstract void shutdown();
+
+    protected abstract boolean isEnabled(MetricsConfiguration config);
+
+    public void updateExporterState(@Nullable MetricsConfiguration config) {
+        this.config = config;
+        if (config != null && isEnabled(config) && meterRegistry != null) {
+            if (!active) {
+                logger.debug("Activating exporter {} ", this.getClass().getSimpleName());
+                active = true;
+                start(Objects.requireNonNull(meterRegistry), config);
+            } else {
+                logger.trace("Exporter {} already active.", this.getClass().getSimpleName());
+            }
+        } else {
+            if (active) {
+                logger.debug("Shutting down exporter {} ", this.getClass().getSimpleName());
+                shutdown();
+                active = false;
+            } else {
+                logger.trace("Exporter {} already shut down.", this.getClass().getSimpleName());
+            }
+        }
+    }
+
+    public void setMeterRegistry(@Nullable CompositeMeterRegistry meterRegistry) {
+        this.meterRegistry = meterRegistry;
+        updateExporterState(config);
+    }
+}

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

@@ -0,0 +1,83 @@
+/**
+ * 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.Objects;
+
+import javax.annotation.security.RolesAllowed;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
+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.io.monitor.MeterRegistryProvider;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.jaxrs.whiteboard.JaxrsWhiteboardConstants;
+import org.osgi.service.jaxrs.whiteboard.propertytypes.JSONRequired;
+import org.osgi.service.jaxrs.whiteboard.propertytypes.JaxrsApplicationSelect;
+import org.osgi.service.jaxrs.whiteboard.propertytypes.JaxrsResource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+import io.micrometer.prometheus.PrometheusConfig;
+import io.micrometer.prometheus.PrometheusMeterRegistry;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+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.
+ *
+ * @author Robert Bach - Initial contribution
+ */
+@Component(immediate = true, service = MetricsRestController.class)
+@JaxrsResource
+@JaxrsApplicationSelect("(" + JaxrsWhiteboardConstants.JAX_RS_NAME + "=" + MetricsService.METRICS_APP_NAME + ")")
+@Path("")
+@JSONRequired
+@RolesAllowed({ Role.USER, Role.ADMIN })
+@Tag(name = MetricsRestController.PATH_METRICS)
+@NonNullByDefault
+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);
+
+    @GET
+    @Path("/prometheus")
+    @Produces(MediaType.TEXT_PLAIN)
+    @Operation(operationId = "getPrometheusMetrics", summary = "Gets openHAB system and core metrics in a Prometheus compatible format.", responses = {
+            @ApiResponse(responseCode = "200", description = "OK", content = @Content(schema = @Schema(implementation = String.class))) })
+    public String getPrometheusMetrics() {
+        return prometheusMeterRegistry.scrape();
+    }
+
+    @Reference
+    public void setMeterRegistryProvider(MeterRegistryProvider meterRegistryProvider) {
+        if (meterRegistry != null) {
+            Objects.requireNonNull(meterRegistry).remove(prometheusMeterRegistry);
+        }
+        meterRegistry = meterRegistryProvider.getOHMeterRegistry();
+        Objects.requireNonNull(meterRegistry).add(prometheusMeterRegistry);
+        logger.debug("Core metrics registry retrieved and Prometheus registry added successfully.");
+    }
+}

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

@@ -0,0 +1,117 @@
+/**
+ * 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));
+    }
+}

bundles/org.openhab.io.metrics/src/main/java/org/openhab/io/metrics/exporters/InfluxMetricsExporter.java

@@ -0,0 +1,99 @@
+/**
+ * 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.exporters;
+
+import java.time.Duration;
+import java.util.Objects;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.io.metrics.MetricsConfiguration;
+import org.openhab.io.metrics.MetricsExporter;
+
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+import io.micrometer.influx.InfluxConfig;
+import io.micrometer.influx.InfluxMeterRegistry;
+
+/**
+ * The {@link InfluxMetricsExporter} class implements a MetricsExporter for InfluxDB
+ *
+ * @author Robert Bach - Initial contribution
+ */
+@NonNullByDefault
+public class InfluxMetricsExporter extends MetricsExporter {
+
+    private @Nullable InfluxMeterRegistry influxMeterRegistry = null;
+    private @Nullable CompositeMeterRegistry meterRegistry = null;
+
+    @Override
+    public void start(CompositeMeterRegistry meterRegistry, MetricsConfiguration metricsConfiguration) {
+        influxMeterRegistry = new InfluxMeterRegistry(getInfluxConfig(metricsConfiguration), Clock.SYSTEM);
+        meterRegistry.add(influxMeterRegistry);
+    }
+
+    @Override
+    public void shutdown() {
+        if (influxMeterRegistry != null) {
+            Objects.requireNonNull(influxMeterRegistry).stop();
+        }
+        if (meterRegistry != null) {
+            Objects.requireNonNull(meterRegistry).remove(influxMeterRegistry);
+            meterRegistry = null;
+        }
+        influxMeterRegistry = null;
+    }
+
+    private InfluxConfig getInfluxConfig(MetricsConfiguration metricsConfiguration) {
+        return new InfluxConfig() {
+            @Override
+            public Duration step() {
+                return Duration.ofSeconds(metricsConfiguration.influxUpdateIntervalInSeconds);
+            }
+
+            @Override
+            public String uri() {
+                return metricsConfiguration.influxURL;
+            }
+
+            @Override
+            public String db() {
+                return metricsConfiguration.influxDB;
+            }
+
+            @Override
+            @Nullable
+            public String userName() {
+                return metricsConfiguration.influxUsername;
+            }
+
+            @Override
+            @Nullable
+            public String password() {
+                return metricsConfiguration.influxPassword;
+            }
+
+            @Override
+            @io.micrometer.core.lang.Nullable
+            @Nullable
+            public String get(@Nullable String k) {
+                return null; // accept the rest of the defaults
+            }
+        };
+    }
+
+    @Override
+    protected boolean isEnabled(MetricsConfiguration config) {
+        return config.influxMetricsEnabled;
+    }
+}

bundles/org.openhab.io.metrics/src/main/resources/OH-INF/config/config.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<config-description:config-descriptions
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:config-description="https://openhab.org/schemas/config-description/v1.0.0"
+	xsi:schemaLocation="https://openhab.org/schemas/config-description/v1.0.0
+		https://openhab.org/schemas/config-description-1.0.0.xsd">
+	<config-description uri="io:metrics">
+		<parameter name="influxMetricsEnabled" type="boolean">
+			<label>Influx Metrics</label>
+			<description>Enable the Influx (www.influxdata.com) Metrics. Further Configuration of the InfluxDB Instance
+				Necessary.</description>
+			<default>false</default>
+		</parameter>
+		<parameter name="influxURL" type="text">
+			<label>InfluxDB URL</label>
+			<description>The URL of the InfluxDB Instance. Defaults to http://localhost:8086</description>
+			<default>http://localhost:8086</default>
+		</parameter>
+		<parameter name="influxDB" type="text">
+			<label>InfluxDB Database Name</label>
+			<description>The Name of the Database to Use. Defaults to "openhab".</description>
+			<default>openhab</default>
+		</parameter>
+		<parameter name="influxUsername" type="text">
+			<label>InfluxDB User Name</label>
+			<description>The InfluxDB User Name (No Default).</description>
+		</parameter>
+		<parameter name="influxPassword" type="text">
+			<label>InfluxDB Password</label>
+			<description>The InfluxDB Password (No Default).</description>
+			<context>password</context>
+		</parameter>
+		<parameter name="influxUpdateIntervalInSeconds" type="integer" unit="s" min="1">
+			<label>InfluxDB Update Interval in Seconds</label>
+			<description>Controls How Often Metrics Are Exported to InfluxDB (in Seconds). Defaults to 300</description>
+			<default>300</default>
+		</parameter>
+	</config-description>
+</config-description:config-descriptions>

bundles/pom.xml

@@ -25,6 +25,7 @@
     <module>org.openhab.io.homekit</module>
     <module>org.openhab.io.hueemulation</module>
     <module>org.openhab.io.imperihome</module>
+    <module>org.openhab.io.metrics</module>
     <module>org.openhab.io.neeo</module>
     <module>org.openhab.io.openhabcloud</module>
     <!-- transformations -->