Adds resolver function for loading S3 client specific config

codegen/smithy-aws-go-codegen/src/main/java/software/amazon/smithy/aws/go/codegen/AddAwsConfigFields.java

@@ -222,11 +222,23 @@ private void writeAwsConfigConstructor(Model model, ServiceShape service, GoWrit
                         }
                     });
 
-                    for (AwsConfigField field : AWS_CONFIG_FIELDS) {
+
+                    List<AwsConfigField> configFields = new ArrayList<>(AWS_CONFIG_FIELDS);
+                    // add client specific config fields
+                    for (AwsConfigField cfgField: ResolveClientConfig.AWS_CONFIG_FIELDS) {
+                        configFields.add(cfgField);
+                    }
+
+                    for (AwsConfigField field : configFields) {
                         Optional<Symbol> awsResolverFunction = field.getAwsResolverFunction();
                         if (!awsResolverFunction.isPresent()) {
                             continue;
                         }
+                        if (field.getServicePredicate().isPresent()) {
+                            if (!field.getServicePredicate().get().test(model, service)) {
+                                continue;
+                            }
+                        }
                         writer.write("$L(cfg, &opts)", awsResolverFunction.get());
                     }
 

codegen/smithy-aws-go-codegen/src/main/java/software/amazon/smithy/aws/go/codegen/AwsGoDependency.java

@@ -34,6 +34,8 @@ public class AwsGoDependency {
     public static final GoDependency AWS_HTTP_TRANSPORT = aws("aws/transport/http", "awshttp");
     public static final GoDependency AWSTESTING_UNIT = aws("internal/awstesting/unit");
 
+    public static final GoDependency S3_SHARED_CONFIG = aws("service/internal/s3shared/config", "s3sharedconfig");
+
     public static final GoDependency REGEXP = SmithyGoDependency.stdlib("regexp");
 
     public static final String AWS_SOURCE_PATH = "github.com/aws/aws-sdk-go-v2";
@@ -82,6 +84,6 @@ protected static GoDependency module(
     }
 
     private static final class Versions {
-        private static final String AWS_SDK = "v0.30.1-0.20201217001905-4acf9c65b2d1";
+        private static final String AWS_SDK = "v0.30.1-0.20201221101722-677dd4a81dad";
     }
 }

codegen/smithy-aws-go-codegen/src/main/java/software/amazon/smithy/aws/go/codegen/ResolveClientConfig.java

@@ -0,0 +1,96 @@
+package software.amazon.smithy.aws.go.codegen;
+
+import java.util.List;
+import java.util.logging.Logger;
+import software.amazon.smithy.aws.traits.ServiceTrait;
+import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.codegen.core.SymbolProvider;
+import software.amazon.smithy.go.codegen.GoDelegator;
+import software.amazon.smithy.go.codegen.GoSettings;
+import software.amazon.smithy.go.codegen.SmithyGoDependency;
+import software.amazon.smithy.go.codegen.SymbolUtils;
+import software.amazon.smithy.go.codegen.integration.GoIntegration;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.utils.ListUtils;
+
+/**
+ * Registers additional client specific configuration fields
+ */
+public class ResolveClientConfig implements GoIntegration {
+    private static final Logger LOGGER = Logger.getLogger(AddAwsConfigFields.class.getName());
+
+    private static final String USE_ARN_REGION_OPTION = "UseARNRegion";
+    private static final String CLIENT_CONFIG_RESOLVER_FUNC = "resolveClientConfig";
+    private static final String CONFIG_SOURCE_CONFIG_NAME = "ConfigSources";
+    private static final String RESOLVE_USE_ARN_REGION= "ResolveUseARNRegion";
+
+    public static final List<AddAwsConfigFields.AwsConfigField> AWS_CONFIG_FIELDS = ListUtils.of(
+            AddAwsConfigFields.AwsConfigField.builder()
+                    .name(USE_ARN_REGION_OPTION)
+                    .type(getUniversalSymbol("boolean"))
+                    .generatedOnClient(false)
+                    .servicePredicate((model, serviceShape) -> {
+                        return isS3SharedService(model, serviceShape);
+                    })
+                    .awsResolveFunction(SymbolUtils.createValueSymbolBuilder(CLIENT_CONFIG_RESOLVER_FUNC)
+                            .build())
+                    .build()
+    );
+
+    @Override
+    public void writeAdditionalFiles(
+            GoSettings settings,
+            Model model,
+            SymbolProvider symbolProvider,
+            GoDelegator goDelegator
+    ) {
+        LOGGER.info("generating client config resolver");
+        ServiceShape serviceShape = settings.getService(model);
+        goDelegator.useShapeWriter(serviceShape, writer -> {
+            if (!isS3SharedService(model, serviceShape)) {
+                return;
+            }
+
+            writer.writeDocs("resolves client config");
+            writer.addUseImports(AwsGoDependency.AWS_CORE);
+            writer.openBlock("func $L(cfg aws.Config, o *Options) error {", "}",
+                    CLIENT_CONFIG_RESOLVER_FUNC, () -> {
+                writer.openBlock("if cfg.$L == nil || len(cfg.$L) == 0 {", "}",
+                        CONFIG_SOURCE_CONFIG_NAME, CONFIG_SOURCE_CONFIG_NAME,
+                        () -> writer.write("return nil")
+                );
+
+                writer.addUseImports(SmithyGoDependency.CONTEXT);
+                Symbol resolverFunc = SymbolUtils.createValueSymbolBuilder(RESOLVE_USE_ARN_REGION,
+                        AwsGoDependency.S3_SHARED_CONFIG).build();
+                writer.write("value, found, err := $T(context.Background(), cfg.$L)", resolverFunc,
+                        CONFIG_SOURCE_CONFIG_NAME);
+                writer.write("if err != nil { return err }");
+                writer.write("if found { o.$L = value }", USE_ARN_REGION_OPTION);
+
+                writer.write("return nil");
+            });
+
+        });
+    }
+
+
+    private static Symbol getUniversalSymbol(String symbolName) {
+        return SymbolUtils.createValueSymbolBuilder(symbolName)
+                .putProperty(SymbolUtils.GO_UNIVERSE_TYPE, true).build();
+    }
+
+    private static boolean isS3SharedService(Model model, ServiceShape service) {
+        return isS3Service(model, service) || isS3ControlService(model, service);
+    }
+
+    private static boolean isS3Service(Model model, ServiceShape service) {
+        return service.expectTrait(ServiceTrait.class).getSdkId().equalsIgnoreCase("S3");
+    }
+
+    private static boolean isS3ControlService(Model model, ServiceShape service) {
+        return service.expectTrait(ServiceTrait.class).getSdkId().equalsIgnoreCase("S3 Control");
+    }
+
+}

codegen/smithy-aws-go-codegen/src/main/resources/META-INF/services/software.amazon.smithy.go.codegen.integration.GoIntegration

@@ -32,3 +32,4 @@ software.amazon.smithy.aws.go.codegen.FilterStreamingOperations
 software.amazon.smithy.aws.go.codegen.RequestResponseLogging
 software.amazon.smithy.aws.go.codegen.customization.S3ControlEndpointResolver
 software.amazon.smithy.aws.go.codegen.AwsHttpPresignURLClientGenerator
+software.amazon.smithy.aws.go.codegen.ResolveClientConfig