[DRAFT] Allow different Micrometer backends to be configured

implementation/pom.xml

@@ -133,6 +133,86 @@
       <artifactId>micrometer-registry-prometheus</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-appoptics</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-atlas</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-datadog</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-dynatrace</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-elastic</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-ganglia</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-graphite</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-humio</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-influx</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-jmx</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-kairos</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-new-relic</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-stackdriver</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-signalfx</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-statsd</artifactId>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-registry-wavefront</artifactId>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
 
   <profiles>

implementation/src/main/java/io/smallrye/metrics/legacyapi/LegacyMetricsExtension.java

@@ -12,6 +12,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Properties;
+import java.util.Set;
 
 import jakarta.enterprise.event.Observes;
 import jakarta.enterprise.inject.spi.AfterDeploymentValidation;
@@ -33,6 +34,8 @@
 import org.eclipse.microprofile.metrics.annotation.Gauge;
 import org.eclipse.microprofile.metrics.annotation.Timed;
 
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Metrics;
 import io.smallrye.metrics.MetricProducer;
 import io.smallrye.metrics.MetricRegistryProducer;
 import io.smallrye.metrics.MetricsRequestHandler;
@@ -47,6 +50,9 @@
 import io.smallrye.metrics.legacyapi.interceptors.MetricResolver;
 import io.smallrye.metrics.legacyapi.interceptors.MetricsBinding;
 import io.smallrye.metrics.legacyapi.interceptors.TimedInterceptor;
+import io.smallrye.metrics.micrometer.Backend;
+import io.smallrye.metrics.micrometer.MicrometerBackends;
+import io.smallrye.metrics.micrometer.RequiresClass;
 import io.smallrye.metrics.setup.MetricsMetadata;
 
 /**
@@ -107,6 +113,16 @@ void registerAnnotatedTypes(@Observes BeforeBeanDiscovery bbd, BeanManager manag
         }) {
             bbd.addAnnotatedType(manager.createAnnotatedType(clazz), extensionName + "_" + clazz.getName());
         }
+
+        for (Class clazz : MicrometerBackends.classes()) {
+            try {
+                final RequiresClass requiresClass = (RequiresClass) clazz.getAnnotation(RequiresClass.class);
+                final Class<?>[] requiredClass = requiresClass.value();
+                bbd.addAnnotatedType(manager.createAnnotatedType(clazz), extensionName + "_" + clazz.getName());
+            } catch (Exception e) {
+                // ignore and don't add
+            }
+        }
     }
 
     /*
@@ -173,6 +189,16 @@ void registerMetrics(@Observes AfterDeploymentValidation adv, BeanManager manage
         // should this be done here, or should it be called by servers consuming this library?
         MetricRegistry baseRegistry = SharedMetricRegistries.getOrCreate(MetricRegistry.BASE_SCOPE);
 
+        // register configured meter registries
+
+        final Set<Bean<?>> beans = manager.getBeans(MeterRegistry.class, MicrometerBackends.class.getAnnotation(Backend.class));
+        for (Bean<?> bean : beans) {
+            final Object reference = manager.getReference(bean, MeterRegistry.class, manager.createCreationalContext(bean));
+            if (MeterRegistry.class.isInstance(reference)) {
+                Metrics.globalRegistry.add(MeterRegistry.class.cast(reference));
+            }
+        }
+
         // Produce and register custom metrics
         MetricRegistry registry = SharedMetricRegistries.getOrCreate(MetricRegistry.APPLICATION_SCOPE);
         BeanInfoAdapter<Class<?>> beanInfoAdapter = new CDIBeanInfoAdapter();

implementation/src/main/java/io/smallrye/metrics/micrometer/Backend.java

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.smallrye.metrics.micrometer;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import jakarta.inject.Qualifier;
+
+@Qualifier
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Backend {
+}