Fix BOOT-INF/classes/ prefix for two-arg openClasspathResource

instrumentation/spring/spring-boot-resources/javaagent-unit-tests/src/test/java/io/opentelemetry/instrumentation/spring/resources/TestBootInfClassesResource.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.instrumentation.spring.resources;
 
 import static io.opentelemetry.semconv.ServiceAttributes.SERVICE_NAME;
+import static io.opentelemetry.semconv.ServiceAttributes.SERVICE_VERSION;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
@@ -30,4 +31,17 @@ void testServiceName() {
     Resource result = guesser.createResource(config);
     assertThat(result.getAttribute(SERVICE_NAME)).isEqualTo("otel-spring-test-app");
   }
+
+  @Test
+  void testServiceVersion() {
+    // verify that the test app, that is added as a dependency to this project, has the expected
+    // layout: build-info.properties lives at the jar root under META-INF/, not under
+    // BOOT-INF/classes/
+    assertThat(getClass().getResource("/META-INF/build-info.properties")).isNotNull();
+    assertThat(getClass().getResource("/BOOT-INF/classes/META-INF/build-info.properties")).isNull();
+
+    SpringBootServiceVersionDetector guesser = new SpringBootServiceVersionDetector();
+    Resource result = guesser.createResource(config);
+    assertThat(result.getAttribute(SERVICE_VERSION)).isEqualTo("1.2.3");
+  }
 }

instrumentation/spring/spring-boot-resources/javaagent/src/main/java/io/opentelemetry/instrumentation/spring/resources/SpringBootServiceVersionDetector.java

@@ -60,7 +60,9 @@ private Resource create() {
   }
 
   private Optional<String> getServiceVersionFromBuildInfo() {
-    try (InputStream in = system.openClasspathResource("META-INF", "build-info.properties")) {
+    // build-info.properties is placed by Spring Boot's buildInfo() at the jar root under META-INF/
+    // (not under BOOT-INF/classes/), so look it up at the jar root.
+    try (InputStream in = system.openJarRootResource("META-INF/build-info.properties")) {
       return in != null ? getServiceVersionPropertyFromStream(in) : Optional.empty();
     } catch (IOException e) {
       return Optional.empty();

instrumentation/spring/spring-boot-resources/javaagent/src/main/java/io/opentelemetry/instrumentation/spring/resources/SystemHelper.java

@@ -39,13 +39,22 @@ String getProperty(String key) {
     return System.getProperty(key);
   }
 
+  /**
+   * Opens a classpath resource that lives alongside the application's classes. In Spring Boot
+   * bootJar layouts the application classes live under {@code BOOT-INF/classes/}, so the prefix is
+   * applied when that layout is detected.
+   */
   InputStream openClasspathResource(String filename) {
     String path = addBootInfPrefix ? "BOOT-INF/classes/" + filename : filename;
     return classLoader.getResourceAsStream(path);
   }
 
-  InputStream openClasspathResource(String directory, String filename) {
-    String path = directory + "/" + filename;
+  /**
+   * Opens a classpath resource that always lives at the jar root, regardless of bootJar layout.
+   * This is used for things like {@code META-INF/build-info.properties}, which Spring Boot places
+   * at the jar root rather than under {@code BOOT-INF/classes/}.
+   */
+  InputStream openJarRootResource(String path) {
     return classLoader.getResourceAsStream(path);
   }
 

instrumentation/spring/spring-boot-resources/javaagent/src/test/java/io/opentelemetry/instrumentation/spring/resources/SpringBootServiceVersionDetectorTest.java

@@ -20,16 +20,15 @@
 @ExtendWith(MockitoExtension.class)
 class SpringBootServiceVersionDetectorTest {
 
-  private static final String BUILD_PROPS = "build-info.properties";
-  private static final String META_INFO = "META-INF";
+  private static final String BUILD_INFO_PATH = "META-INF/build-info.properties";
 
   @Mock ConfigProperties config;
   @Mock SystemHelper system;
 
   @Test
   void givenBuildVersionIsPresentInBuildInfProperties_thenReturnBuildVersion() {
-    when(system.openClasspathResource(META_INFO, BUILD_PROPS))
-        .thenReturn(openClasspathResource(META_INFO + "/" + BUILD_PROPS));
+    when(system.openJarRootResource(BUILD_INFO_PATH))
+        .thenReturn(openClasspathResource(BUILD_INFO_PATH));
 
     SpringBootServiceVersionDetector guesser = new SpringBootServiceVersionDetector(system);
     Resource result = guesser.createResource(config);
@@ -38,7 +37,7 @@ void givenBuildVersionIsPresentInBuildInfProperties_thenReturnBuildVersion() {
 
   @Test
   void givenBuildVersionFileNotPresent_thenReturnEmptyResource() {
-    when(system.openClasspathResource(META_INFO, BUILD_PROPS)).thenReturn(null);
+    when(system.openJarRootResource(BUILD_INFO_PATH)).thenReturn(null);
 
     SpringBootServiceVersionDetector guesser = new SpringBootServiceVersionDetector(system);
     Resource result = guesser.createResource(config);
@@ -47,8 +46,8 @@ void givenBuildVersionFileNotPresent_thenReturnEmptyResource() {
 
   @Test
   void givenBuildVersionFileIsPresentButBuildVersionPropertyNotPresent_thenReturnEmptyResource() {
-    when(system.openClasspathResource(META_INFO, BUILD_PROPS))
-        .thenReturn(openClasspathResource(BUILD_PROPS));
+    when(system.openJarRootResource(BUILD_INFO_PATH))
+        .thenReturn(openClasspathResource("build-info.properties"));
 
     SpringBootServiceVersionDetector guesser = new SpringBootServiceVersionDetector(system);
     Resource result = guesser.createResource(config);