feedback and doc update

codegen/smithy-aws-go-codegen/src/main/java/software/amazon/smithy/aws/go/codegen/customization/S3UpdateEndpoint.java

@@ -26,6 +26,7 @@
 import software.amazon.smithy.go.codegen.GoDelegator;
 import software.amazon.smithy.go.codegen.GoSettings;
 import software.amazon.smithy.go.codegen.GoWriter;
+import software.amazon.smithy.go.codegen.SmithyGoDependency;
 import software.amazon.smithy.go.codegen.SymbolUtils;
 import software.amazon.smithy.go.codegen.integration.ConfigField;
 import software.amazon.smithy.go.codegen.integration.GoIntegration;
@@ -148,6 +149,10 @@ private void writeInputGetter(GoWriter writer, Model model, SymbolProvider symbo
     }
 
     private void writeS3ControlMiddlewareHelper(GoWriter writer) {
+        // imports
+        writer.addUseImports(SmithyGoDependency.SMITHY_MIDDLEWARE);
+        writer.addUseImports(AwsCustomGoDependency.S3CONTROL_CUSTOMIZATION);
+
         writer.openBlock("func $L(stack *middleware.Stack, options Options) {", "}", UPDATE_ENDPOINT_ADDER, () -> {
             writer.write("$T(stack, $T{UseDualstack: options.$L})",
                     SymbolUtils.createValueSymbolBuilder(UPDATE_ENDPOINT_INTERNAL_ADDER,
@@ -160,6 +165,10 @@ private void writeS3ControlMiddlewareHelper(GoWriter writer) {
     }
 
     private void writeS3MiddlewareHelper(GoWriter writer) {
+        // imports
+        writer.addUseImports(SmithyGoDependency.SMITHY_MIDDLEWARE);
+        writer.addUseImports(AwsCustomGoDependency.S3_CUSTOMIZATION);
+
         writer.openBlock("func $L(stack *middleware.Stack, options Options) {", "}", UPDATE_ENDPOINT_ADDER, () -> {
             writer.write("$T(stack, $T{ \n"
                             + "Region: options.Region,\n GetBucketFromInput: $L,\n UsePathStyle: options.$L,\n "
@@ -219,7 +228,7 @@ public List<RuntimeClientPlugin> getClientPlugins() {
                             .type(SymbolUtils.createValueSymbolBuilder("bool")
                                 .putProperty(SymbolUtils.GO_UNIVERSE_TYPE, true)
                                 .build())
-                            .documentation("")
+                            .documentation("Allows you to enable Dualstack endpoint support for the service.")
                             .build()
                         ))
                         .registerMiddleware(MiddlewareRegistrar.builder()

service/s3/internal/customizations/doc.go

@@ -3,7 +3,7 @@ Package customizations provides customizations for the Amazon S3 API client.
 
 This package provides support for following S3 customizations
 
-    UpdateEndpoint Middleware: Virtual Host style url addressing
+    UpdateEndpoint Middleware: resolves a custom endpoint as per s3 config options
 
     processResponseWith200Error Middleware: Deserializing response error with 200 status code
 
@@ -12,17 +12,34 @@ Virtual Host style url addressing
 
 Since serializers serialize by default as path style url, we use customization
 to modify the endpoint url when `UsePathStyle` option on S3Client is unset or
-false.
+false. This flag will be ignored if `UseAccelerate` option is set to true.
 
-UpdateEndpoint middleware handler for virtual host url addressing needs to be
+
+Transfer acceleration
+
+By default S3 Transfer acceleration support is disabled. By enabling `UseAccelerate`
+option on S3Client, one can enable s3 transfer acceleration support. Transfer
+acceleration only works with Virtual Host style addressing, and thus `UsePathStyle`
+option if set is ignored. Transfer acceleration is not supported for S3 operations
+DeleteBucket, ListBuckets, and CreateBucket.
+
+Dualstack support
+
+By default dualstack support for s3 client is disabled. By enabling `UseDualstack`
+option on s3 client, you can enable dualstack endpoint support.
+
+
+UpdateEndpoint middleware handler for modifying resolved endpoint needs to be
 executed after request serialization.
 
-    Middleware layering:
+ Middleware layering:
 
-    HTTP Request -> operation serializer -> Update-Endpoint customization -> next middleware
+ HTTP Request -> operation serializer -> Update-Endpoint customization -> next middleware
 
-Customization option:
-    UsePathStyle (Disabled by Default)
+Customization options:
+ UsePathStyle (Disabled by Default)
+ UseAccelerate (Disabled by Default)
+ UseDualstack (Disabled by Default)
 
 Handle Error response with 200 status code
 
@@ -36,9 +53,9 @@ than response deserialization. Since the behavior of Deserialization is in
 reverse order to the other stack steps its easier to consider that "after" means
 "before".
 
-    Middleware layering:
+ Middleware layering:
 
-	HTTP Response -> handle 200 error customization -> deserialize
+ HTTP Response -> handle 200 error customization -> deserialize
 
 */
 package customizations

service/s3/internal/customizations/update_endpoint.go

@@ -111,38 +111,39 @@ func (u *updateEndpointMiddleware) HandleSerialize(
 
 func (u updateEndpointMiddleware) updateEndpointFromConfig(req *http.Request, bucket string) error {
 	// do nothing if path style is enforced
-	if !u.usePathStyle {
-		if !hostCompatibleBucketName(req.URL, bucket) {
-			// bucket name must be valid to put into the host
-			return fmt.Errorf("bucket name %s is not compatible with S3", bucket)
-		}
+	if u.usePathStyle {
+		return nil
+	}
 
-		// accelerate is only supported if use path style is disabled
-		if u.useAccelerate {
-			parts := strings.Split(req.URL.Host, ".")
-			if len(parts) < 3 {
-				return fmt.Errorf("unable to update endpoint host for S3 accelerate, hostname invalid, %s", req.URL.Host)
-			}
+	if !hostCompatibleBucketName(req.URL, bucket) {
+		// bucket name must be valid to put into the host
+		return fmt.Errorf("bucket name %s is not compatible with S3", bucket)
+	}
 
-			if parts[0] == "s3" || strings.HasPrefix(parts[0], "s3-") {
-				parts[0] = "s3-accelerate"
-			}
+	// accelerate is only supported if use path style is disabled
+	if u.useAccelerate {
+		parts := strings.Split(req.URL.Host, ".")
+		if len(parts) < 3 {
+			return fmt.Errorf("unable to update endpoint host for S3 accelerate, hostname invalid, %s", req.URL.Host)
+		}
 
-			for i := 1; i+1 < len(parts); i++ {
-				if strings.EqualFold(parts[i], u.region) {
-					parts = append(parts[:i], parts[i+1:]...)
-					break
-				}
-			}
+		if parts[0] == "s3" || strings.HasPrefix(parts[0], "s3-") {
+			parts[0] = "s3-accelerate"
+		}
 
-			// construct the url host
-			req.URL.Host = strings.Join(parts, ".")
+		for i := 1; i+1 < len(parts); i++ {
+			if strings.EqualFold(parts[i], u.region) {
+				parts = append(parts[:i], parts[i+1:]...)
+				break
+			}
 		}
 
-		// move bucket to follow virtual host style
-		moveBucketNameToHost(req.URL, bucket)
+		// construct the url host
+		req.URL.Host = strings.Join(parts, ".")
 	}
 
+	// move bucket to follow virtual host style
+	moveBucketNameToHost(req.URL, bucket)
 	return nil
 }
 

service/s3control/internal/customizations/doc.go

@@ -0,0 +1,26 @@
+/*
+Package customizations provides customizations for the Amazon S3-Control API client.
+
+This package provides support for following S3-Control customizations
+
+    UpdateEndpoint Middleware: resolves a custom endpoint as per s3-control config options
+
+
+Dualstack support
+
+By default dualstack support for s3-control client is disabled. By enabling `UseDualstack`
+option on s3-control client, you can enable dualstack endpoint support.
+
+
+UpdateEndpoint middleware handler for modifying resolved endpoint needs to be
+executed after request serialization.
+
+ Middleware layering:
+
+ HTTP Request -> operation serializer -> Update-Endpoint customization -> next middleware
+
+Customization option:
+ UseDualstack (Disabled by Default)
+
+*/
+package customizations