don't fail spring application startup if sdk is disabled

Author: zeitlinger

instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/exporters/internal/ExporterConfigEvaluator.java

@@ -19,6 +19,10 @@ private ExporterConfigEvaluator() {}
   public static boolean isExporterEnabled(
       Environment environment, String exportersKey, String wantExporter, boolean defaultValue) {
 
+    if (environment.getProperty("otel.sdk.disabled", Boolean.class, false)) {
+      return false;
+    }
+
     String exporter = environment.getProperty(exportersKey);
     if (exporter != null) {
       return Arrays.asList(exporter.split(",")).contains(wantExporter);

instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/propagators/PropagationAutoConfiguration.java

@@ -15,6 +15,7 @@
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
@@ -26,6 +27,7 @@
 @EnableConfigurationProperties(PropagationProperties.class)
 @AutoConfigureBefore(OpenTelemetryAutoConfiguration.class)
 @ConditionalOnProperty(prefix = "otel.propagation", name = "enabled", matchIfMissing = true)
+@ConditionalOnBean(ConfigProperties.class)
 public class PropagationAutoConfiguration {
 
   private static final List<String> DEFAULT_PROPAGATORS = Arrays.asList("tracecontext", "baggage");

smoke-tests-otel-starter/src/test/java/io/opentelemetry/smoketest/OtelSpringStarterDisabledSmokeTest.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.smoketest;
+
+import io.opentelemetry.spring.smoketest.OtelSpringStarterSmokeTestApplication;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest(
+    classes = {
+      OtelSpringStarterSmokeTestApplication.class,
+      OtelSpringStarterSmokeTest.TestConfiguration.class
+    },
+    properties = {"otel.sdk.disabled=true"})
+class OtelSpringStarterDisabledSmokeTest {
+
+  @Test
+  void shouldStartApplication() {
+    // make sure we can still start the application with the disabled property
+  }
+}