add config model customizer

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfiguration.java

@@ -108,10 +108,19 @@ public static OpenTelemetrySdk create(OpenTelemetryConfigurationModel configurat
    */
   public static OpenTelemetrySdk create(
       OpenTelemetryConfigurationModel configurationModel, ComponentLoader componentLoader) {
+    SpiHelper spiHelper = SpiHelper.create(componentLoader);
+
+    DeclarativeConfigurationBuilder builder = new DeclarativeConfigurationBuilder();
+
+    for (DeclarativeConfigurationCustomizerProvider provider :
+        spiHelper.loadOrdered(DeclarativeConfigurationCustomizerProvider.class)) {
+      provider.customize(builder);
+    }
+
     return createAndMaybeCleanup(
         OpenTelemetryConfigurationFactory.getInstance(),
-        SpiHelper.create(componentLoader),
-        configurationModel);
+        spiHelper,
+        builder.customizeModel(configurationModel));
   }
 
   /**

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfigurationBuilder.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.incubator.fileconfig;
+
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.OpenTelemetryConfigurationModel;
+import java.util.function.Function;
+
+/** Builder for the declarative configuration. */
+public class DeclarativeConfigurationBuilder implements DeclarativeConfigurationCustomizer {
+  private Function<OpenTelemetryConfigurationModel, OpenTelemetryConfigurationModel>
+      modelCustomizer = Function.identity();
+
+  @Override
+  public void addModelCustomizer(
+      Function<OpenTelemetryConfigurationModel, OpenTelemetryConfigurationModel> customizer) {
+    modelCustomizer = mergeCustomizer(modelCustomizer, customizer);
+  }
+
+  private static <I, O1, O2> Function<I, O2> mergeCustomizer(
+      Function<? super I, ? extends O1> first, Function<? super O1, ? extends O2> second) {
+    return (I configured) -> {
+      O1 firstResult = first.apply(configured);
+      return second.apply(firstResult);
+    };
+  }
+
+  /** Customize the configuration model. */
+  public OpenTelemetryConfigurationModel customizeModel(
+      OpenTelemetryConfigurationModel configurationModel) {
+    return modelCustomizer.apply(configurationModel);
+  }
+}

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfigurationCustomizer.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.incubator.fileconfig;
+
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.OpenTelemetryConfigurationModel;
+import java.util.function.Function;
+
+/** A service provider interface (SPI) for customizing declarative configuration. */
+public interface DeclarativeConfigurationCustomizer {
+  /**
+   * Method invoked when configuring the SDK to allow further customization of the declarative
+   * configuration.
+   *
+   * @param customizer the customizer to add
+   */
+  void addModelCustomizer(
+      Function<OpenTelemetryConfigurationModel, OpenTelemetryConfigurationModel> customizer);
+}

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfigurationCustomizerProvider.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.incubator.fileconfig;
+
+import io.opentelemetry.sdk.autoconfigure.spi.Ordered;
+
+/** A service provider interface (SPI) for customizing declarative configuration. */
+public interface DeclarativeConfigurationCustomizerProvider extends Ordered {
+  /**
+   * Method invoked when configuring the SDK to allow further customization of the declarative
+   *
+   * @param customizer the customizer to add
+   */
+  void customize(DeclarativeConfigurationCustomizer customizer);
+}

sdk-extensions/incubator/src/test/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfigurationCreateTest.java

@@ -14,6 +14,11 @@
 import io.github.netmikey.logunit.api.LogCapturer;
 import io.opentelemetry.api.incubator.config.DeclarativeConfigException;
 import io.opentelemetry.internal.testing.CleanupExtension;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.autoconfigure.internal.SpiHelper;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.OpenTelemetryConfigurationModel;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.SpanProcessorModel;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.TracerProviderModel;
 import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.IOException;
@@ -22,6 +27,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.security.cert.CertificateEncodingException;
+import java.util.Collections;
 import java.util.Objects;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
@@ -61,7 +67,7 @@ void parseAndCreate_Examples(@TempDir Path tempDir)
             tempDir, "clientCertificate.cert", clientTls.certificate().getEncoded());
 
     File examplesDir = new File(System.getenv("CONFIG_EXAMPLE_DIR"));
-    assertThat(examplesDir.isDirectory()).isTrue();
+    assertThat(examplesDir).isDirectory();
 
     for (File example : Objects.requireNonNull(examplesDir.listFiles())) {
       // Skip anchors.yaml because support for merge (i.e. "<<: *anchor") was explicitly removed in
@@ -151,4 +157,32 @@ void parseAndCreate_EmptyComponentProviderConfig() {
                     new ByteArrayInputStream(yaml.getBytes(StandardCharsets.UTF_8))))
         .doesNotThrowAnyException();
   }
+
+  @Test
+  void create_ModelCustomizer() {
+    OpenTelemetryConfigurationModel model = new OpenTelemetryConfigurationModel();
+    model.withFileFormat("0.3");
+    model.withTracerProvider(
+        new TracerProviderModel()
+            .withProcessors(
+                Collections.singletonList(
+                    new SpanProcessorModel().withAdditionalProperty("test", null))));
+    OpenTelemetrySdk sdk =
+        DeclarativeConfiguration.create(
+            model,
+            // customizer is TestDeclarativeConfigurationCustomizerProvider
+            SpiHelper.serviceComponentLoader(
+                DeclarativeConfigurationCreateTest.class.getClassLoader()));
+    assertThat(sdk.toString())
+        .contains(
+            "resource=Resource{schemaUrl=null, attributes={"
+                + "color=\"blue\", "
+                + "foo=\"bar\", "
+                + "order=\"second\", "
+                + "service.name=\"unknown_service:java\", "
+                + "shape=\"square\", "
+                + "telemetry.sdk.language=\"java\", "
+                + "telemetry.sdk.name=\"opentelemetry\", "
+                + "telemetry.sdk.version=\"");
+  }
 }

sdk-extensions/incubator/src/test/java/io/opentelemetry/sdk/extension/incubator/fileconfig/TestDeclarativeConfigurationCustomizerProvider.java

@@ -0,0 +1,38 @@
+package io.opentelemetry.sdk.extension.incubator.fileconfig;
+
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.AttributeNameValueModel;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.ResourceModel;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class TestDeclarativeConfigurationCustomizerProvider
+    implements DeclarativeConfigurationCustomizerProvider {
+  @Override
+  public void customize(DeclarativeConfigurationCustomizer customizer) {
+    customizer.addModelCustomizer(
+        model -> {
+          ResourceModel resource = model.getResource();
+          if (resource == null) {
+            resource = new ResourceModel();
+            model.withResource(resource);
+          }
+          List<AttributeNameValueModel> attributes = resource.getAttributes();
+          if (attributes == null) {
+            attributes = new ArrayList<>();
+            resource.withAttributes(attributes);
+          }
+          attributes.add(
+              new AttributeNameValueModel()
+                  .withName("foo")
+                  .withType(AttributeNameValueModel.Type.STRING)
+                  .withValue("bar"));
+          attributes.add(
+              new AttributeNameValueModel()
+                  .withName("color")
+                  .withType(AttributeNameValueModel.Type.STRING)
+                  .withValue("blue"));
+          return model;
+        });
+  }
+}

sdk-extensions/incubator/src/test/resources/META-INF/services/io.opentelemetry.sdk.extension.incubator.fileconfig.DeclarativeConfigurationCustomizerProvider

@@ -0,0 +1 @@
+io.opentelemetry.sdk.extension.incubator.fileconfig.TestDeclarativeConfigurationCustomizerProvider