Fix metrics autoconfiguration ordering for Spring Boot 4 (#2758)

Author: cretz

temporal-spring-boot-autoconfigure/build.gradle

@@ -46,6 +46,10 @@ dependencies {
     testImplementation "org.mockito:mockito-core:${mockitoVersion}"
 
     testImplementation "org.springframework.boot:spring-boot-starter-test"
+    // For auto-configuration ordering tests (metrics)
+    testImplementation "org.springframework.boot:spring-boot-starter-actuator"
+    // For auto-configuration ordering tests (OpenTelemetry)
+    testImplementation "io.opentelemetry:opentelemetry-sdk"
 
     if (project.hasProperty("springBoot4Test")) {
         // Override the SB 2.7 BOM for test classpath so tests run against SB 4.
@@ -55,6 +59,10 @@ dependencies {
         // SB4 requires SLF4J 2.x + Logback 1.5+; let the SB4 BOM provide them
         // instead of using the root project's pinned versions.
         testRuntimeOnly "org.junit.platform:junit-platform-launcher"
+        // SB4 modularized auto-configs into separate modules that
+        // spring-boot-starter-actuator no longer transitively includes.
+        testImplementation "org.springframework.boot:spring-boot-micrometer-metrics"
+        testImplementation "org.springframework.boot:spring-boot-opentelemetry"
     } else {
         testImplementation group: 'ch.qos.logback', name: 'logback-classic', version: "${logbackVersion}"
         testImplementation('org.slf4j:slf4j-api') {

temporal-spring-boot-autoconfigure/src/main/java/io/temporal/spring/boot/autoconfigure/MetricsScopeAutoConfiguration.java

@@ -14,8 +14,10 @@
 
 @Configuration
 @AutoConfigureAfter(
-    name =
-        "org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration")
+    name = {
+      "org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration",
+      "org.springframework.boot.micrometer.metrics.autoconfigure.CompositeMeterRegistryAutoConfiguration"
+    })
 @ConditionalOnBean(MeterRegistry.class)
 public class MetricsScopeAutoConfiguration {
   @Bean(name = "temporalMetricsScope", destroyMethod = "close")

temporal-spring-boot-autoconfigure/src/main/java/io/temporal/spring/boot/autoconfigure/OpenTracingAutoConfiguration.java

@@ -14,7 +14,13 @@
 @Configuration
 @ConditionalOnClass(io.opentelemetry.api.OpenTelemetry.class)
 @ConditionalOnBean(io.opentelemetry.api.OpenTelemetry.class)
-@AutoConfigureAfter(name = "org.springframework.cloud.sleuth.autoconfig.otel.OtelAutoConfiguration")
+@AutoConfigureAfter(
+    name = {
+      "org.springframework.cloud.sleuth.autoconfig.otel.OtelAutoConfiguration",
+      "org.springframework.boot.actuate.autoconfigure.tracing.OpenTelemetryAutoConfiguration",
+      "org.springframework.boot.actuate.autoconfigure.opentelemetry.OpenTelemetryAutoConfiguration",
+      "org.springframework.boot.opentelemetry.autoconfigure.OpenTelemetrySdkAutoConfiguration"
+    })
 public class OpenTracingAutoConfiguration {
   @ConditionalOnMissingBean(Tracer.class)
   @Bean(name = "temporalOtTracer")

temporal-spring-boot-autoconfigure/src/test/java/io/temporal/spring/boot/autoconfigure/AutoConfigOrderingTest.java

@@ -0,0 +1,109 @@
+package io.temporal.spring.boot.autoconfigure;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+/**
+ * Tests that {@link MetricsScopeAutoConfiguration} and {@link OpenTracingAutoConfiguration}
+ * correctly order themselves after their dependency auto-configurations via
+ * {@code @AutoConfigureAfter}.
+ *
+ * <p>Without correct ordering, {@code @ConditionalOnBean} evaluates before the dependency beans
+ * exist, silently skipping our entire auto-configuration. This happens because our FQCNs ({@code
+ * io.temporal...}) sort alphabetically before Spring's ({@code org.springframework...}), which is
+ * the default processing order when no ordering constraints are specified.
+ */
+class AutoConfigOrderingTest {
+
+  /**
+   * Try to load a class by name, returning the first match found. Returns null if none of the class
+   * names exist on the classpath.
+   */
+  private static Class<?> findClass(String... classNames) {
+    for (String name : classNames) {
+      try {
+        return Class.forName(name);
+      } catch (ClassNotFoundException ignored) {
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Verifies that {@link MetricsScopeAutoConfiguration} runs after {@code
+   * CompositeMeterRegistryAutoConfiguration} and finds the {@code MeterRegistry} bean it creates.
+   * The {@code CompositeMeterRegistryAutoConfiguration} class moved packages in Spring Boot 4 —
+   * both old and new names must be in {@code @AutoConfigureAfter}.
+   */
+  @Test
+  void metricsScopeCreatedWithAutoConfigOrdering() {
+    Class<?> compositeClass =
+        findClass(
+            // SB 2.7 / 3.x
+            "org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration",
+            // SB 4.0
+            "org.springframework.boot.micrometer.metrics.autoconfigure.CompositeMeterRegistryAutoConfiguration");
+
+    assumeTrue(compositeClass != null, "CompositeMeterRegistryAutoConfiguration not on classpath");
+
+    // MetricsAutoConfiguration provides the Clock bean that CompositeMeterRegistryAutoConfiguration
+    // inner configs need to activate.
+    List<Class<?>> autoConfigs = new ArrayList<>();
+    autoConfigs.add(MetricsScopeAutoConfiguration.class);
+    autoConfigs.add(compositeClass);
+    Class<?> metricsAutoConfig =
+        findClass(
+            "org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration",
+            "org.springframework.boot.micrometer.metrics.autoconfigure.MetricsAutoConfiguration");
+    if (metricsAutoConfig != null) {
+      autoConfigs.add(metricsAutoConfig);
+    }
+
+    new ApplicationContextRunner()
+        .withConfiguration(AutoConfigurations.of(autoConfigs.toArray(new Class<?>[0])))
+        .run(
+            context -> {
+              assertThat(context).hasNotFailed();
+              assertThat(context).hasBean("temporalMetricsScope");
+            });
+  }
+
+  /**
+   * Verifies that {@link OpenTracingAutoConfiguration} runs after the OpenTelemetry
+   * auto-configuration and finds the {@code OpenTelemetry} bean it creates. The producing class
+   * moved across Spring Boot versions:
+   *
+   * <ul>
+   *   <li>SB 3.2+: {@code actuate.autoconfigure.opentelemetry.OpenTelemetryAutoConfiguration}
+   *   <li>SB 4.0: {@code opentelemetry.autoconfigure.OpenTelemetrySdkAutoConfiguration}
+   * </ul>
+   *
+   * <p>On SB 2.7 (no native OTel auto-config) this test is skipped.
+   */
+  @Test
+  void openTracingTracerCreatedWithAutoConfigOrdering() {
+    Class<?> otelAutoConfig =
+        findClass(
+            // SB 3.2+ (generic OTel auto-config, uses ObjectProvider for optional deps)
+            "org.springframework.boot.actuate.autoconfigure.opentelemetry.OpenTelemetryAutoConfiguration",
+            // SB 4.0 (relocated to separate module)
+            "org.springframework.boot.opentelemetry.autoconfigure.OpenTelemetrySdkAutoConfiguration");
+
+    assumeTrue(otelAutoConfig != null, "OpenTelemetry auto-configuration not on classpath");
+
+    new ApplicationContextRunner()
+        .withConfiguration(
+            AutoConfigurations.of(OpenTracingAutoConfiguration.class, otelAutoConfig))
+        .run(
+            context -> {
+              assertThat(context).hasNotFailed();
+              assertThat(context).hasBean("temporalOtTracer");
+            });
+  }
+}