BAEL-5867: Micrometer Observability API with Spring Boot 3 (#13180)

* BAEL-5867: Create project and create first usage main method

* BAEL-5867: Use Observation API in Boot

* BAEL-5867: Refactoring and testing

* BAEL-5867: Add tracing

* BAEL-5867: Remove notes and add project as a module to the aggregator

* BAEL-5867: Fix pmd rules violation

pom.xml

@@ -1168,6 +1168,7 @@
                  <module>spring-boot-modules/spring-boot-camel</module>
                  <module>spring-boot-modules/spring-boot-3</module>
                  <module>spring-boot-modules/spring-boot-3-native</module>
+                <module>spring-boot-modules/spring-boot-3-observation</module>
                  <module>spring-swagger-codegen/custom-validations-opeanpi-codegen</module>
                  <module>testing-modules/testing-assertions</module>
                  <module>persistence-modules/fauna</module>
@@ -1251,6 +1252,7 @@
                 <module>spring-boot-modules/spring-boot-camel</module>
                 <module>spring-boot-modules/spring-boot-3</module>
                 <module>spring-boot-modules/spring-boot-3-native</module>
+                <module>spring-boot-modules/spring-boot-3-observation</module>
                 <module>spring-swagger-codegen/custom-validations-opeanpi-codegen</module>
                 <module>testing-modules/testing-assertions</module>
                 <module>persistence-modules/fauna</module>

spring-boot-modules/spring-boot-3-observation/pom.xml

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>spring-boot-3-observation</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>spring-boot-3-observation</name>
+    <description>Demo project for Spring Boot 3 Observation</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-3</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-tracing</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-tracing-bridge-brave</artifactId>
+            <!--artifactId>micrometer-tracing-bridge-otel</artifactId-->
+        </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-observation-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-tracing-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <!-- get ObservationRegistry configured -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-actuator</artifactId>
+        </dependency>
+        <!-- @Observed -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-aop</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-devtools</artifactId>
+            <scope>runtime</scope>
+            <optional>true</optional>
+        </dependency>
+
+    </dependencies>
+
+</project>

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/GreetingApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.samples;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class GreetingApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(GreetingApplication.class, args);
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/SimpleObservationApplication.java

@@ -0,0 +1,66 @@
+package com.baeldung.samples;
+
+import io.micrometer.core.instrument.Measurement;
+import io.micrometer.core.instrument.Statistic;
+import io.micrometer.core.instrument.observation.DefaultMeterObservationHandler;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.ObservationTextPublisher;
+
+import java.util.Optional;
+import java.util.stream.StreamSupport;
+
+public class SimpleObservationApplication {
+
+    // we can run this as a simple command line application
+    public static void main(String[] args) {
+        // create registry
+        final var observationRegistry = ObservationRegistry.create();
+        // create meter registry and observation handler
+        final var meterRegistry = new SimpleMeterRegistry();
+        final var meterObservationHandler = new DefaultMeterObservationHandler(meterRegistry);
+        // create simple logging observation handler
+        final var loggingObservationHandler = new ObservationTextPublisher(System.out::println);
+        // register observation handlers
+        observationRegistry
+          .observationConfig()
+          .observationHandler(meterObservationHandler)
+          .observationHandler(loggingObservationHandler);
+        // make an observation
+        Observation.Context context = new Observation.Context();
+        String observationName = "obs1";
+        Observation observation = Observation
+          .createNotStarted(observationName, () -> context, observationRegistry)
+          .lowCardinalityKeyValue("gender", "male")
+          .highCardinalityKeyValue("age", "41");
+
+        for (int i = 0; i < 10; i++) {
+            observation.observe(SimpleObservationApplication::doSomeAction);
+        }
+
+        meterRegistry.getMeters().forEach(m -> {
+            System.out.println(m.getId() + "\n============");
+            m.measure().forEach(ms -> System.out.println(ms.getValue() + " [" + ms.getStatistic() + "]"));
+            System.out.println("----------------------------");
+        });
+        Optional<Double> maximumDuration = meterRegistry.getMeters().stream()
+          .filter(m -> "obs1".equals(m.getId().getName()))
+          .flatMap(m -> StreamSupport.stream(m.measure().spliterator(), false))
+          .filter(ms -> ms.getStatistic() == Statistic.MAX)
+          .findFirst()
+          .map(Measurement::getValue);
+
+        System.out.println(maximumDuration);
+    }
+
+    private static void doSomeAction() {
+        try {
+            Thread.sleep(Math.round(Math.random() * 1000));
+            System.out.println("Hello World!");
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/boundary/GreetingController.java

@@ -0,0 +1,26 @@
+package com.baeldung.samples.boundary;
+
+import com.baeldung.samples.domain.GreetingService;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+@Controller
+@RequestMapping("/greet")
+public class GreetingController {
+
+    private final GreetingService service;
+
+    public GreetingController(GreetingService service) {
+        this.service = service;
+    }
+
+    @GetMapping(produces = MediaType.TEXT_PLAIN_VALUE)
+    @ResponseBody
+    public String sayHello() {
+        return this.service.sayHello();
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/boundary/ObservationFilterConfiguration.java

@@ -0,0 +1,22 @@
+package com.baeldung.samples.boundary;
+
+import io.micrometer.observation.ObservationRegistry;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.filter.ServerHttpObservationFilter;
+
+@Configuration
+public class ObservationFilterConfiguration {
+
+    // if an ObservationRegistry is already configured
+    @ConditionalOnBean(ObservationRegistry.class)
+    // if we do not use Actuator
+    @ConditionalOnMissingBean(ServerHttpObservationFilter.class)
+    @Bean
+    public ServerHttpObservationFilter observationFilter(ObservationRegistry registry) {
+        return new ServerHttpObservationFilter(registry);
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/config/ObservationHandlerLogger.java

@@ -0,0 +1,28 @@
+package com.baeldung.samples.config;
+
+import io.micrometer.observation.ObservationHandler;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.event.ContextRefreshedEvent;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ObservationHandlerLogger {
+
+    private static final Logger log = LoggerFactory.getLogger(ObservationHandlerLogger.class);
+
+    private static String toString(ObservationHandler<?> handler) {
+        return handler.getClass().getName() + " [ " + handler + "]";
+    }
+
+    @EventListener(ContextRefreshedEvent.class)
+    public void logObservationHandlers(ContextRefreshedEvent evt) {
+        evt.getApplicationContext().getBeansOfType(ObservationHandler.class)
+          .values()
+          .stream()
+          .map(ObservationHandlerLogger::toString)
+          .forEach(log::info);
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/config/ObservationTextPublisherConfiguration.java

@@ -0,0 +1,21 @@
+package com.baeldung.samples.config;
+
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationHandler;
+import io.micrometer.observation.ObservationTextPublisher;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class ObservationTextPublisherConfiguration {
+
+    private static final Logger log = LoggerFactory.getLogger(ObservationTextPublisherConfiguration.class);
+
+    @Bean
+    public ObservationHandler<Observation.Context> observationTextPublisher() {
+        return new ObservationTextPublisher(log::info);
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/config/ObservedAspectConfiguration.java

@@ -0,0 +1,20 @@
+package com.baeldung.samples.config;
+
+import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.aop.ObservedAspect;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.context.annotation.Bean;
+
+@AutoConfiguration
+@ConditionalOnClass(ObservedAspect.class)
+public class ObservedAspectConfiguration {
+
+    @Bean
+    @ConditionalOnMissingBean
+    public ObservedAspect observedAspect(ObservationRegistry observationRegistry) {
+        return new ObservedAspect(observationRegistry);
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/config/SimpleLoggingHandler.java

@@ -0,0 +1,59 @@
+package com.baeldung.samples.config;
+
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationHandler;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+public class SimpleLoggingHandler implements ObservationHandler<Observation.Context> {
+
+    private static final Logger log = LoggerFactory.getLogger(SimpleLoggingHandler.class);
+
+    private static String toString(Observation.Context context) {
+        return null == context ? "(no context)" : context.getName()
+          + " (" + context.getClass().getName() + "@" + System.identityHashCode(context) + ")";
+    }
+
+    private static String toString(Observation.Event event) {
+        return null == event ? "(no event)" : event.getName();
+    }
+
+    @Override
+    public boolean supportsContext(Observation.Context context) {
+        return true;
+    }
+
+    @Override
+    public void onStart(Observation.Context context) {
+        log.info("Starting context " + toString(context));
+    }
+
+    @Override
+    public void onError(Observation.Context context) {
+        log.info("Error for context " + toString(context));
+    }
+
+    @Override
+    public void onEvent(Observation.Event event, Observation.Context context) {
+        log.info("Event for context " + toString(context) + " [" + toString(event) + "]");
+    }
+
+    @Override
+    public void onScopeOpened(Observation.Context context) {
+        log.info("Scope opened for context " + toString(context));
+
+    }
+
+    @Override
+    public void onScopeClosed(Observation.Context context) {
+        log.info("Scope closed for context " + toString(context));
+    }
+
+    @Override
+    public void onStop(Observation.Context context) {
+        log.info("Stopping context " + toString(context));
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/java/com/baeldung/samples/domain/GreetingService.java

@@ -0,0 +1,14 @@
+package com.baeldung.samples.domain;
+
+import io.micrometer.observation.annotation.Observed;
+import org.springframework.stereotype.Service;
+
+@Observed(name = "greetingService")
+@Service
+public class GreetingService {
+
+    public String sayHello() {
+        return "Hello World!";
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/main/resources/application.yml

@@ -0,0 +1,6 @@
+management:
+  endpoints:
+    web:
+      exposure:
+        include: '*'
+        #health,info,beans,metrics,startup

spring-boot-modules/spring-boot-3-observation/src/test/java/com/baeldung/samples/config/SimpleLoggingHandlerUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.samples.config;
+
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationHandler;
+import io.micrometer.observation.tck.AnyContextObservationHandlerCompatibilityKit;
+
+class SimpleLoggingHandlerUnitTest
+  extends AnyContextObservationHandlerCompatibilityKit {
+
+    SimpleLoggingHandler handler = new SimpleLoggingHandler();
+
+    @Override
+    public ObservationHandler<Observation.Context> handler() {
+        return handler;
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/test/java/com/baeldung/samples/domain/EnableTestObservation.java

@@ -0,0 +1,44 @@
+package com.baeldung.samples.domain;
+
+import com.baeldung.samples.config.ObservedAspectConfiguration;
+import io.micrometer.observation.tck.TestObservationRegistry;
+import io.micrometer.tracing.test.simple.SimpleTracer;
+import org.springframework.boot.test.autoconfigure.actuate.observability.AutoConfigureObservability;
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Inherited
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+@AutoConfigureObservability
+@Import({
+  ObservedAspectConfiguration.class,
+  EnableTestObservation.ObservationTestConfiguration.class
+})
+public @interface EnableTestObservation {
+
+    @TestConfiguration
+    class ObservationTestConfiguration {
+
+        @Bean
+        TestObservationRegistry observationRegistry() {
+            return TestObservationRegistry.create();
+        }
+
+        @Bean
+        SimpleTracer simpleTracer() {
+            return new SimpleTracer();
+        }
+
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/test/java/com/baeldung/samples/domain/GreetingServiceObservationIntegrationTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.samples.domain;
+
+import io.micrometer.observation.tck.TestObservationRegistry;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import static io.micrometer.observation.tck.TestObservationRegistryAssert.assertThat;
+
+@ExtendWith(SpringExtension.class)
+@ComponentScan(basePackageClasses = GreetingService.class)
+@EnableAutoConfiguration
+@EnableTestObservation
+class GreetingServiceObservationIntegrationTest {
+
+    @Autowired
+    GreetingService service;
+    @Autowired
+    TestObservationRegistry registry;
+
+    @Test
+    void testObservation() {
+        // invoke service
+        service.sayHello();
+        assertThat(registry)
+          .hasObservationWithNameEqualTo("greetingService")
+          .that()
+          .hasBeenStarted()
+          .hasBeenStopped();
+    }
+
+}

spring-boot-modules/spring-boot-3-observation/src/test/java/com/baeldung/samples/domain/GreetingServiceTracingIntegrationTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.samples.domain;
+
+import io.micrometer.tracing.test.simple.SimpleTracer;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import static io.micrometer.tracing.test.simple.TracerAssert.assertThat;
+
+@ExtendWith(SpringExtension.class)
+@ComponentScan(basePackageClasses = GreetingService.class)
+@EnableAutoConfiguration
+@EnableTestObservation
+class GreetingServiceTracingIntegrationTest {
+
+    @Autowired
+    GreetingService service;
+    @Value("${management.tracing.enabled:true}")
+    boolean tracingEnabled;
+    @Autowired
+    SimpleTracer tracer;
+
+    @Test
+    void testEnabledTracing() {
+        Assertions.assertThat(tracingEnabled).isTrue();
+    }
+
+    @Test
+    void testTracingForGreeting() {
+        service.sayHello();
+        assertThat(tracer)
+          .onlySpan()
+          .hasNameEqualTo("greeting-service#say-hello")
+          .isEnded();
+    }
+
+}