Add 'logging' as new metric export type

module/spring-boot-micrometer-metrics/src/main/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/LoggingMetricsExportAutoConfiguration.java

@@ -0,0 +1,63 @@
+/*
+ * 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.micrometer.metrics.autoconfigure.export.logging;
+
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.logging.LoggingMeterRegistry;
+import io.micrometer.core.instrument.logging.LoggingRegistryConfig;
+
+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.boot.micrometer.metrics.autoconfigure.CompositeMeterRegistryAutoConfiguration;
+import org.springframework.boot.micrometer.metrics.autoconfigure.MetricsAutoConfiguration;
+import org.springframework.boot.micrometer.metrics.autoconfigure.export.ConditionalOnEnabledMetricsExport;
+import org.springframework.boot.micrometer.metrics.autoconfigure.export.simple.SimpleMetricsExportAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for exporting metrics to a
+ * {@link LoggingMeterRegistry}.
+ *
+ * @author Vasily Pelikh
+ * @since 4.0.0
+ */
+@AutoConfiguration(
+		before = { CompositeMeterRegistryAutoConfiguration.class, SimpleMetricsExportAutoConfiguration.class },
+		after = MetricsAutoConfiguration.class)
+@ConditionalOnBean(Clock.class)
+@ConditionalOnClass(LoggingMeterRegistry.class)
+@ConditionalOnEnabledMetricsExport("logging")
+@EnableConfigurationProperties(LoggingMetricsExportProperties.class)
+public final class LoggingMetricsExportAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean
+	LoggingRegistryConfig loggingRegistryConfig(LoggingMetricsExportProperties loggingMetricsExportProperties) {
+		return new LoggingMetricsExportPropertiesConfigAdapter(loggingMetricsExportProperties);
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	LoggingMeterRegistry loggingMeterRegistry(LoggingRegistryConfig config, Clock clock) {
+		return new LoggingMeterRegistry(config, clock);
+	}
+
+}

module/spring-boot-micrometer-metrics/src/main/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/LoggingMetricsExportProperties.java

@@ -0,0 +1,47 @@
+/*
+ * 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.micrometer.metrics.autoconfigure.export.logging;
+
+import io.micrometer.core.instrument.logging.LoggingMeterRegistry;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.micrometer.metrics.autoconfigure.export.properties.StepRegistryProperties;
+
+/**
+ * {@link ConfigurationProperties @ConfigurationProperties} for configuring metrics export
+ * to a {@link LoggingMeterRegistry}.
+ *
+ * @author Vasily Pelikh
+ * @since 4.0.0
+ */
+@ConfigurationProperties("management.logging.metrics.export")
+public class LoggingMetricsExportProperties extends StepRegistryProperties {
+
+	/**
+	 * Whether counters and timers that have no activity in an interval are still logged.
+	 */
+	private boolean logInactive = false;
+
+	public boolean isLogInactive() {
+		return this.logInactive;
+	}
+
+	public void setLogInactive(boolean logInactive) {
+		this.logInactive = logInactive;
+	}
+
+}

module/spring-boot-micrometer-metrics/src/main/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/LoggingMetricsExportPropertiesConfigAdapter.java

@@ -0,0 +1,47 @@
+/*
+ * 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.micrometer.metrics.autoconfigure.export.logging;
+
+import io.micrometer.core.instrument.logging.LoggingRegistryConfig;
+
+import org.springframework.boot.micrometer.metrics.autoconfigure.export.properties.StepRegistryPropertiesConfigAdapter;
+
+/**
+ * Adapter to convert {@link LoggingMetricsExportProperties} to a
+ * {@link LoggingRegistryConfig}.
+ *
+ * @author Vasily Pelikh
+ * @since 4.0.0
+ */
+public class LoggingMetricsExportPropertiesConfigAdapter
+		extends StepRegistryPropertiesConfigAdapter<LoggingMetricsExportProperties> implements LoggingRegistryConfig {
+
+	public LoggingMetricsExportPropertiesConfigAdapter(LoggingMetricsExportProperties properties) {
+		super(properties);
+	}
+
+	@Override
+	public String prefix() {
+		return "management.logging.metrics.export";
+	}
+
+	@Override
+	public boolean logInactive() {
+		return obtain(LoggingMetricsExportProperties::isLogInactive, LoggingRegistryConfig.super::logInactive);
+	}
+
+}

module/spring-boot-micrometer-metrics/src/main/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/package-info.java

@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+
+/**
+ * Support for exporting actuator metrics to a log.
+ */
+@NullMarked
+package org.springframework.boot.micrometer.metrics.autoconfigure.export.logging;
+
+import org.jspecify.annotations.NullMarked;

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

@@ -13,6 +13,7 @@ org.springframework.boot.micrometer.metrics.autoconfigure.export.humio.HumioMetr
 org.springframework.boot.micrometer.metrics.autoconfigure.export.influx.InfluxMetricsExportAutoConfiguration
 org.springframework.boot.micrometer.metrics.autoconfigure.export.jmx.JmxMetricsExportAutoConfiguration
 org.springframework.boot.micrometer.metrics.autoconfigure.export.kairos.KairosMetricsExportAutoConfiguration
+org.springframework.boot.micrometer.metrics.autoconfigure.export.logging.LoggingMetricsExportAutoConfiguration
 org.springframework.boot.micrometer.metrics.autoconfigure.export.newrelic.NewRelicMetricsExportAutoConfiguration
 org.springframework.boot.micrometer.metrics.autoconfigure.export.otlp.OtlpMetricsExportAutoConfiguration
 org.springframework.boot.micrometer.metrics.autoconfigure.export.prometheus.PrometheusMetricsExportAutoConfiguration

module/spring-boot-micrometer-metrics/src/test/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/LoggingMetricsExportAutoConfigurationTests.java

@@ -0,0 +1,128 @@
+/*
+ * 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.micrometer.metrics.autoconfigure.export.logging;
+
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.logging.LoggingMeterRegistry;
+import io.micrometer.core.instrument.logging.LoggingRegistryConfig;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link LoggingMetricsExportAutoConfiguration}.
+ *
+ * @author Vasily Pelikh
+ */
+class LoggingMetricsExportAutoConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withConfiguration(AutoConfigurations.of(LoggingMetricsExportAutoConfiguration.class));
+
+	@Test
+	void backsOffWithoutAClock() {
+		this.contextRunner.run((context) -> assertThat(context).doesNotHaveBean(LoggingMeterRegistry.class)
+			.doesNotHaveBean(LoggingRegistryConfig.class));
+	}
+
+	@Test
+	void backOffWhenLoggingMeterRegistryIsMissing() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+			.withClassLoader(new FilteredClassLoader(LoggingMeterRegistry.class))
+			.run((context) -> assertThat(context).doesNotHaveBean(LoggingMeterRegistry.class)
+				.doesNotHaveBean(LoggingRegistryConfig.class));
+	}
+
+	@Test
+	void autoConfiguresConfigAndMeterRegistry() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+			.run((context) -> assertThat(context).hasSingleBean(LoggingMeterRegistry.class)
+				.hasSingleBean(LoggingRegistryConfig.class));
+	}
+
+	@Test
+	void autoConfigurationCanBeDisabledWithDefaultsEnabledProperty() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+			.withPropertyValues("management.defaults.metrics.export.enabled=false")
+			.run((context) -> assertThat(context).doesNotHaveBean(LoggingMeterRegistry.class)
+				.doesNotHaveBean(LoggingRegistryConfig.class));
+	}
+
+	@Test
+	void autoConfigurationCanBeDisabledWithSpecificEnabledProperty() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+			.withPropertyValues("management.logging.metrics.export.enabled=false")
+			.run((context) -> assertThat(context).doesNotHaveBean(LoggingMeterRegistry.class)
+				.doesNotHaveBean(LoggingRegistryConfig.class));
+	}
+
+	@Test
+	void allowsCustomConfigToBeUsed() {
+		this.contextRunner.withUserConfiguration(CustomConfigConfiguration.class)
+			.run((context) -> assertThat(context).hasSingleBean(LoggingMeterRegistry.class)
+				.hasSingleBean(LoggingRegistryConfig.class)
+				.hasBean("customConfig"));
+	}
+
+	@Test
+	void allowsRegistryToBeCustomized() {
+		this.contextRunner.withUserConfiguration(CustomRegistryConfiguration.class)
+			.run((context) -> assertThat(context).hasSingleBean(LoggingMeterRegistry.class)
+				.hasSingleBean(LoggingRegistryConfig.class)
+				.hasBean("customRegistry"));
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class BaseConfiguration {
+
+		@Bean
+		Clock customClock() {
+			return Clock.SYSTEM;
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@Import(BaseConfiguration.class)
+	static class CustomConfigConfiguration {
+
+		@Bean
+		LoggingRegistryConfig customConfig() {
+			return (key) -> null;
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@Import(BaseConfiguration.class)
+	static class CustomRegistryConfiguration {
+
+		@Bean
+		LoggingMeterRegistry customRegistry(LoggingRegistryConfig config, Clock clock) {
+			return new LoggingMeterRegistry(config, clock);
+		}
+
+	}
+
+}

module/spring-boot-micrometer-metrics/src/test/java/org/springframework/boot/micrometer/metrics/autoconfigure/export/logging/LoggingMetricsExportPropertiesConfigAdapterTests.java

@@ -0,0 +1,53 @@
+/*
+ * 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.micrometer.metrics.autoconfigure.export.logging;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link LoggingMetricsExportPropertiesConfigAdapter}.
+ *
+ * @author Vasily Pelikh
+ */
+class LoggingMetricsExportPropertiesConfigAdapterTests {
+
+	private LoggingMetricsExportProperties properties;
+
+	@BeforeEach
+	void setUp() {
+		this.properties = new LoggingMetricsExportProperties();
+	}
+
+	@Test
+	void whenPropertiesLogInactiveIsNotSetAdapterLogInactiveReturnsFalse() {
+		assertThat(createAdapter().logInactive()).isFalse();
+	}
+
+	@Test
+	void whenPropertiesLogInactiveIsSetAdapterLogInactiveReturnsIt() {
+		this.properties.setLogInactive(true);
+		assertThat(createAdapter().logInactive()).isTrue();
+	}
+
+	private LoggingMetricsExportPropertiesConfigAdapter createAdapter() {
+		return new LoggingMetricsExportPropertiesConfigAdapter(this.properties);
+	}
+
+}