Adding OpenTelemetry tracing

src/main/java/com/redhat/springmusic/config/OtelDataSourceConfig.java

@@ -10,6 +10,10 @@
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.instrumentation.jdbc.datasource.JdbcTelemetry;
 
+/**
+ * This class is needed to allow tracing down to the JDBC level.
+ * Taken from https://opentelemetry.io/docs/languages/java/automatic/spring-boot/#jdbc-instrumentation
+ */
 @Configuration
 public class OtelDataSourceConfig {
 	@Bean

src/main/java/com/redhat/springmusic/config/SpanAspectConfig.java

@@ -0,0 +1,73 @@
+package com.redhat.springmusic.config;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.SimpleEvaluationContext;
+
+import io.micrometer.common.annotation.NoOpValueResolver;
+import io.micrometer.common.annotation.ValueExpressionResolver;
+import io.micrometer.common.annotation.ValueResolver;
+import io.micrometer.tracing.Tracer;
+import io.micrometer.tracing.annotation.DefaultNewSpanParser;
+import io.micrometer.tracing.annotation.ImperativeMethodInvocationProcessor;
+import io.micrometer.tracing.annotation.MethodInvocationProcessor;
+import io.micrometer.tracing.annotation.NewSpanParser;
+import io.micrometer.tracing.annotation.SpanAspect;
+
+/**
+ * This class is needed in order for @NewSpan and @SpanTag annotations to work
+ * See https://docs.micrometer.io/tracing/reference/api.html
+ */
+@Configuration
+public class SpanAspectConfig {
+	@Bean
+	NewSpanParser newSpanParser() {
+		return new DefaultNewSpanParser();
+	}
+
+	@Bean
+	ValueResolver valueResolver() {
+		return new NoOpValueResolver();
+	}
+
+	@Bean
+	ValueExpressionResolver valueExpressionResolver() {
+		return new SpelTagValueExpressionResolver();
+	}
+
+	@Bean
+	MethodInvocationProcessor methodInvocationProcessor(NewSpanParser newSpanParser, Tracer tracer, BeanFactory beanFactory) {
+		return new ImperativeMethodInvocationProcessor(newSpanParser, tracer, beanFactory::getBean, beanFactory::getBean);
+	}
+
+	@Bean
+	SpanAspect spanAspect(MethodInvocationProcessor methodInvocationProcessor) {
+		return new SpanAspect(methodInvocationProcessor);
+	}
+
+	// Example of using SpEL to resolve expressions in @SpanTag
+	static class SpelTagValueExpressionResolver implements ValueExpressionResolver {
+		private static final Log log = LogFactory.getLog(SpelTagValueExpressionResolver.class);
+
+		@Override
+		public String resolve(String expression, Object parameter) {
+			try {
+				var context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
+				var expressionParser = new SpelExpressionParser();
+				var expressionToEvaluate = expressionParser.parseExpression(expression);
+
+				return expressionToEvaluate.getValue(context, parameter, String.class);
+			}
+			catch (Exception ex) {
+				log.error("Exception occurred while tying to evaluate the SpEL expression [" + expression + "]", ex);
+			}
+
+			return parameter.toString();
+		}
+	}
+}

src/main/java/com/redhat/springmusic/listener/AlbumEventListener.java

@@ -22,8 +22,8 @@ protected AlbumEventListener(OutboxEventService outboxEventService) {
 	}
 
 	@EventListener
-	@NewSpan(name = "AlbumEventListener.handleAlbumEvent")
-	public void handleAlbumEvent(@SpanTag(key = "albumEvent") AlbumEvent albumEvent) {
+	@NewSpan("AlbumEventListener.handleAlbumEvent")
+	public void handleAlbumEvent(@SpanTag(key = "arg.albumEvent") AlbumEvent albumEvent) {
 		Assert.notNull(albumEvent, "albumEvent can not be null");
 		LOGGER.info("Handling AlbumEvent {}", albumEvent);
 

src/main/java/com/redhat/springmusic/service/AlbumEventPublishingService.java

@@ -30,15 +30,15 @@ public AlbumEventPublishingService(AlbumRepository albumRepository, ApplicationE
 	}
 
 	@Override
-	@NewSpan(name = "AlbumService.getAllAlbums")
+	@NewSpan("AlbumService.getAllAlbums")
 	public Iterable<Album> getAllAlbums() {
 		LOGGER.info("Getting all albums");
 		return this.albumRepository.findAll();
 	}
 
 	@Override
 	@Transactional
-	@NewSpan(name = "AlbumService.createAlbum")
+	@NewSpan("AlbumService.createAlbum")
 	public Album createAlbum(@SpanTag(key = "arg.album") Album album) {
 		LOGGER.info("Creating album {}", album);
 
@@ -50,7 +50,7 @@ public Album createAlbum(@SpanTag(key = "arg.album") Album album) {
 
 	@Override
 	@Transactional
-	@NewSpan(name = "AlbumService.updateAlbum")
+	@NewSpan("AlbumService.updateAlbum")
 	public void updateAlbum(@SpanTag(key = "arg.album") Album album) {
 		this.albumRepository.findById(album.getId())
 			.map(this.albumRepository::detach)
@@ -61,15 +61,15 @@ public void updateAlbum(@SpanTag(key = "arg.album") Album album) {
 	}
 
 	@Override
-	@NewSpan(name = "AlbumService.getAlbum")
+	@NewSpan("AlbumService.getAlbum")
 	public Optional<Album> getAlbum(@SpanTag(key = "arg.albumId") String albumId) {
 		LOGGER.info("Getting album {}", albumId);
 		return this.albumRepository.findById(albumId);
 	}
 
 	@Override
 	@Transactional
-	@NewSpan(name = "AlbumService.deleteAlbum")
+	@NewSpan("AlbumService.deleteAlbum")
 	public void deleteAlbum(@SpanTag(key = "arg.albumId") String albumId) {
 		this.albumRepository.findById(albumId)
 			.map(this.albumRepository::detach)

src/main/java/com/redhat/springmusic/service/DefaultOutboxEventService.java

@@ -27,32 +27,32 @@ public DefaultOutboxEventService(OutboxEventRepository outboxEventRepository) {
 	}
 
 	@Override
-	@NewSpan(name = "OutboxEventService.getAllEventsOrderedByTimestampDescending")
+	@NewSpan("OutboxEventService.getAllEventsOrderedByTimestampDescending")
 	public Iterable<OutboxEvent> getAllEventsOrderedByTimestampDescending() {
 		LOGGER.info("Getting all album events ordered by timestamp descending");
 		return this.outboxEventRepository.findAll(Sort.by("eventTimestamp").descending());
 	}
 
 	@Override
-	@NewSpan(name = "OutboxEventService.getById")
+	@NewSpan("OutboxEventService.getById")
 	public Optional<OutboxEvent> getById(@SpanTag(key = "arg.eventId") long eventId) {
 		return this.outboxEventRepository.findById(eventId);
 	}
 
 	@Override
-	@NewSpan(name = "OutboxEventService.getAllEventsForAlbumIdOrderedByTimestampDescending")
+	@NewSpan("OutboxEventService.getAllEventsForAlbumIdOrderedByTimestampDescending")
 	public Iterable<OutboxEvent> getAllEventsForAlbumIdOrderedByTimestampDescending(@SpanTag(key = "arg.albumId") String albumId) {
 		return this.outboxEventRepository.findAllByAggregateIdOrderByEventTimestampDesc(albumId);
 	}
 
 	@Override
-	@NewSpan(name = "OutboxEventService.deleteAllEvents")
+	@NewSpan("OutboxEventService.deleteAllEvents")
 	public void deleteAllEvents() {
 		this.outboxEventRepository.deleteAll();
 	}
 
 	@Override
-	@NewSpan(name = "OutboxEventService.persistEvent")
+	@NewSpan("OutboxEventService.persistEvent")
 	public OutboxEvent persistEvent(@SpanTag(key = "arg.event") AlbumEvent event) {
 		return this.outboxEventRepository.save(
 			OutboxEvent.builder()