Add experimental ConditionalResourceProvider interface (#4731)

* Add experimental ConditionalResourceProvider interface

* Add tests

sdk-extensions/autoconfigure-spi/src/main/java/io/opentelemetry/sdk/autoconfigure/spi/internal/ConditionalResourceProvider.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure.spi.internal;
+
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
+import io.opentelemetry.sdk.resources.Resource;
+
+/**
+ * A resource provider that is only applied if the {@link #shouldApply(ConfigProperties, Resource)}
+ * method returns {@code true}.
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+public interface ConditionalResourceProvider extends ResourceProvider {
+
+  /**
+   * If an implementation needs to apply only under certain conditions related to the config or the
+   * existing state of the Resource being built, they can choose to override this default.
+   *
+   * @param config The auto configuration properties
+   * @param existing The current state of the Resource being created
+   * @return false to skip over this ResourceProvider, or true to use it
+   */
+  boolean shouldApply(ConfigProperties config, Resource existing);
+}

sdk-extensions/autoconfigure/build.gradle.kts

@@ -47,6 +47,21 @@ testing {
         }
       }
     }
+    val testConditionalResourceProvider by registering(JvmTestSuite::class) {
+      dependencies {
+        implementation(project(":semconv"))
+      }
+
+      targets {
+        all {
+          testTask {
+            environment("OTEL_TRACES_EXPORTER", "none")
+            environment("OTEL_METRICS_EXPORTER", "none")
+            environment("OTEL_LOGS_EXPORTER", "none")
+          }
+        }
+      }
+    }
     val testConfigError by registering(JvmTestSuite::class) {
       dependencies {
         implementation(project(":extensions:trace-propagators"))

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/ResourceConfiguration.java

@@ -9,6 +9,7 @@ import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.common.AttributesBuilder;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
+import io.opentelemetry.sdk.autoconfigure.spi.internal.ConditionalResourceProvider;
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.resources.ResourceBuilder;
 import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
@@ -46,6 +47,10 @@ final class ResourceConfiguration {
       if (disabledProviders.contains(resourceProvider.getClass().getName())) {
         continue;
       }
+      if (resourceProvider instanceof ConditionalResourceProvider
+          && !((ConditionalResourceProvider) resourceProvider).shouldApply(config, result)) {
+        continue;
+      }
       result = result.merge(resourceProvider.createResource(config));
     }
 

sdk-extensions/autoconfigure/src/testConditionalResourceProvider/java/io/opentelemetry/sdk/autoconfigure/ConditionalResourceProviderTest.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure;
+
+import static java.util.Collections.singletonMap;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.entry;
+
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
+import org.junit.jupiter.api.Test;
+
+class ConditionalResourceProviderTest {
+
+  @Test
+  void shouldConditionallyProvideResourceAttributes_skipBasedOnPreviousResource() {
+    AutoConfiguredOpenTelemetrySdk sdk =
+        AutoConfiguredOpenTelemetrySdk.builder()
+            .setResultAsGlobal(false)
+            .registerShutdownHook(false)
+            .build();
+
+    assertThat(sdk.getResource().getAttributes().asMap())
+        .contains(entry(ResourceAttributes.SERVICE_NAME, "test-service"));
+  }
+
+  @Test
+  void shouldConditionallyProvideResourceAttributes_skipBasedOnConfig() {
+    AutoConfiguredOpenTelemetrySdk sdk =
+        AutoConfiguredOpenTelemetrySdk.builder()
+            .setResultAsGlobal(false)
+            .registerShutdownHook(false)
+            .addPropertiesSupplier(() -> singletonMap("skip-first-resource-provider", "true"))
+            .build();
+
+    assertThat(sdk.getResource().getAttributes().asMap())
+        .contains(entry(ResourceAttributes.SERVICE_NAME, "test-service-2"));
+  }
+}

sdk-extensions/autoconfigure/src/testConditionalResourceProvider/java/io/opentelemetry/sdk/autoconfigure/FirstResourceProvider.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.internal.ConditionalResourceProvider;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
+
+public class FirstResourceProvider implements ConditionalResourceProvider {
+
+  @Override
+  public Resource createResource(ConfigProperties config) {
+    return Resource.create(Attributes.of(ResourceAttributes.SERVICE_NAME, "test-service"));
+  }
+
+  @Override
+  public int order() {
+    return 100;
+  }
+
+  @Override
+  public boolean shouldApply(ConfigProperties config, Resource existing) {
+    return !config.getBoolean("skip-first-resource-provider", false);
+  }
+}

sdk-extensions/autoconfigure/src/testConditionalResourceProvider/java/io/opentelemetry/sdk/autoconfigure/SecondResourceProvider.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.internal.ConditionalResourceProvider;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
+
+public class SecondResourceProvider implements ConditionalResourceProvider {
+
+  @Override
+  public Resource createResource(ConfigProperties config) {
+    return Resource.create(Attributes.of(ResourceAttributes.SERVICE_NAME, "test-service-2"));
+  }
+
+  @Override
+  public int order() {
+    return 200;
+  }
+
+  @Override
+  public boolean shouldApply(ConfigProperties config, Resource existing) {
+    String serviceName = existing.getAttribute(ResourceAttributes.SERVICE_NAME);
+    return serviceName == null || "unknown_service:java".equals(serviceName);
+  }
+}

sdk-extensions/autoconfigure/src/testConditionalResourceProvider/resources/META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider

@@ -0,0 +1,2 @@
+io.opentelemetry.sdk.autoconfigure.SecondResourceProvider
+io.opentelemetry.sdk.autoconfigure.FirstResourceProvider