Add auto-configuration for OpenTelemetry SdkMeterProvider

module/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/OpenTelemetrySdkAutoConfiguration.java

@@ -20,6 +20,7 @@
 import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.OpenTelemetrySdkBuilder;
+import io.opentelemetry.sdk.common.Clock;
 import io.opentelemetry.sdk.logs.LogRecordProcessor;
 import io.opentelemetry.sdk.logs.SdkLoggerProvider;
 import io.opentelemetry.sdk.logs.SdkLoggerProviderBuilder;
@@ -44,6 +45,7 @@
  * {@link EnableAutoConfiguration Auto-configuration} for the OpenTelemetry SDK.
  *
  * @author Moritz Halbritter
+ * @author Thomas Vitale
  * @since 4.0.0
  */
 @AutoConfiguration
@@ -68,6 +70,12 @@ OpenTelemetrySdk openTelemetrySdk(ObjectProvider<SdkTracerProvider> openTelemetr
 		return builder.build();
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	Clock clock() {
+		return Clock.getDefault();
+	}
+
 	@Bean
 	@ConditionalOnMissingBean
 	Resource openTelemetryResource(Environment environment, OpenTelemetryProperties properties) {

module/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/metrics/OpenTelemetryMetricsAutoConfiguration.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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 org.springframework.boot.opentelemetry.autoconfigure.metrics;
+
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.metrics.Meter;
+import io.opentelemetry.sdk.common.Clock;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder;
+import io.opentelemetry.sdk.metrics.export.CardinalityLimitSelector;
+import io.opentelemetry.sdk.metrics.internal.SdkMeterProviderUtil;
+import io.opentelemetry.sdk.metrics.internal.exemplar.ExemplarFilter;
+import io.opentelemetry.sdk.resources.Resource;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for OpenTelemetry Metrics.
+ *
+ * @author Thomas Vitale
+ * @since 4.0.0
+ */
+@AutoConfiguration
+@ConditionalOnClass(SdkMeterProvider.class)
+@EnableConfigurationProperties(OpenTelemetryMetricsProperties.class)
+public final class OpenTelemetryMetricsAutoConfiguration {
+
+	static final String INSTRUMENTATION_SCOPE_NAME = "org.springframework.boot";
+
+	@Bean
+	@ConditionalOnMissingBean
+	@ConditionalOnBean({ Clock.class, Resource.class })
+	SdkMeterProvider meterProvider(Clock clock, ExemplarFilter exemplarFilter,
+			OpenTelemetryMetricsProperties properties, Resource resource,
+			ObjectProvider<SdkMeterProviderBuilderCustomizer> customizers) {
+		SdkMeterProviderBuilder builder = SdkMeterProvider.builder().setClock(clock).setResource(resource);
+		if (properties.getExemplars().isEnabled()) {
+			SdkMeterProviderUtil.setExemplarFilter(builder, exemplarFilter);
+		}
+		customizers.orderedStream().forEach((customizer) -> customizer.customize(builder));
+		return builder.build();
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	CardinalityLimitSelector cardinalityLimitSelector(OpenTelemetryMetricsProperties properties) {
+		return (instrumentType) -> properties.getCardinalityLimit();
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	ExemplarFilter exemplarFilter(OpenTelemetryMetricsProperties properties) {
+		return switch (properties.getExemplars().getFilter()) {
+			case ALWAYS_ON -> ExemplarFilter.alwaysOn();
+			case ALWAYS_OFF -> ExemplarFilter.alwaysOff();
+			case TRACE_BASED -> ExemplarFilter.traceBased();
+		};
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	@ConditionalOnBean(OpenTelemetry.class)
+	Meter meter(OpenTelemetry openTelemetry) {
+		return openTelemetry.getMeter(INSTRUMENTATION_SCOPE_NAME);
+	}
+
+}

module/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/metrics/OpenTelemetryMetricsProperties.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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 org.springframework.boot.opentelemetry.autoconfigure.metrics;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * Configuration properties for OpenTelemetry Metrics.
+ *
+ * @author Thomas Vitale
+ * @since 4.0.0
+ */
+@ConfigurationProperties("management.opentelemetry.metrics")
+public class OpenTelemetryMetricsProperties {
+
+	/**
+	 * Configuration for exemplars.
+	 */
+	private final Exemplars exemplars = new Exemplars();
+
+	/**
+	 * Maximum number of distinct points per metric.
+	 */
+	private Integer cardinalityLimit = 2000;
+
+	public Exemplars getExemplars() {
+		return this.exemplars;
+	}
+
+	public Integer getCardinalityLimit() {
+		return this.cardinalityLimit;
+	}
+
+	public void setCardinalityLimit(Integer cardinalityLimit) {
+		this.cardinalityLimit = cardinalityLimit;
+	}
+
+	/**
+	 * Configuration properties for exemplars.
+	 */
+	public static class Exemplars {
+
+		/**
+		 * Whether exemplars should be enabled.
+		 */
+		private boolean enabled = false;
+
+		/**
+		 * Determines which measurements are eligible to become Exemplars.
+		 */
+		private ExemplarFilter filter = ExemplarFilter.TRACE_BASED;
+
+		public boolean isEnabled() {
+			return this.enabled;
+		}
+
+		public void setEnabled(boolean enabled) {
+			this.enabled = enabled;
+		}
+
+		public ExemplarFilter getFilter() {
+			return this.filter;
+		}
+
+		public void setFilter(ExemplarFilter filter) {
+			this.filter = filter;
+		}
+
+	}
+
+	/**
+	 * Filter for which measurements are eligible to become Exemplars.
+	 */
+	public enum ExemplarFilter {
+
+		/**
+		 * Filter which makes all measurements eligible for being an exemplar.
+		 */
+		ALWAYS_ON,
+
+		/**
+		 * Filter which makes no measurements eligible for being an exemplar.
+		 */
+		ALWAYS_OFF,
+
+		/**
+		 * Filter that only accepts measurements where there is a span in context that is
+		 * being sampled.
+		 */
+		TRACE_BASED
+
+	}
+
+}

module/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/metrics/SdkMeterProviderBuilderCustomizer.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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 org.springframework.boot.opentelemetry.autoconfigure.metrics;
+
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder;
+
+/**
+ * Callback that can be used to customize the {@link SdkMeterProviderBuilder} used to
+ * build the auto-configured {@link SdkMeterProvider}.
+ *
+ * @author Thomas Vitale
+ * @since 4.0.0
+ */
+@FunctionalInterface
+public interface SdkMeterProviderBuilderCustomizer {
+
+	/**
+	 * Customize the given {@code builder}.
+	 * @param builder the builder to customize
+	 */
+	void customize(SdkMeterProviderBuilder builder);
+
+}

module/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/metrics/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.
+ */
+
+/**
+ * Auto-configuration for OpenTelemetry Metrics.
+ */
+package org.springframework.boot.opentelemetry.autoconfigure.metrics;

module/spring-boot-opentelemetry/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -1,2 +1,3 @@
 org.springframework.boot.opentelemetry.autoconfigure.OpenTelemetrySdkAutoConfiguration
 org.springframework.boot.opentelemetry.autoconfigure.logging.OpenTelemetryLoggingExportAutoConfiguration
+org.springframework.boot.opentelemetry.autoconfigure.metrics.OpenTelemetryMetricsAutoConfiguration