add feature tracking for cbor protocol

aws/middleware/user_agent.go

@@ -85,6 +85,7 @@ const (
 	UserAgentFeatureS3ExpressBucket                         = "J"
 	UserAgentFeatureS3AccessGrants                          = "K" // not yet implemented
 	UserAgentFeatureGZIPRequestCompression                  = "L"
+	UserAgentFeatureProtocolRPCV2CBOR                       = "M"
 )
 
 // RequestUserAgent is a build middleware that set the User-Agent for the request.

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

@@ -0,0 +1,88 @@
+package software.amazon.smithy.aws.go.codegen.customization;
+
+import static software.amazon.smithy.go.codegen.GoWriter.goTemplate;
+import static software.amazon.smithy.go.codegen.SymbolUtils.buildPackageSymbol;
+
+import java.util.List;
+import java.util.Map;
+import java.util.function.BiPredicate;
+import software.amazon.smithy.aws.go.codegen.AwsGoDependency;
+import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.go.codegen.GoCodegenContext;
+import software.amazon.smithy.go.codegen.GoWriter;
+import software.amazon.smithy.go.codegen.SmithyGoTypes;
+import software.amazon.smithy.go.codegen.integration.GoIntegration;
+import software.amazon.smithy.go.codegen.integration.MiddlewareRegistrar;
+import software.amazon.smithy.go.codegen.integration.RuntimeClientPlugin;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.protocol.traits.Rpcv2CborTrait;
+
+/**
+ * Adds user agent tracking for basic features - i.e. simple model-based ones that do not require any additional in-code
+ * checks, such as a particular protocol.
+ */
+public class BasicUserAgentFeatures implements GoIntegration {
+    private static final List<Feature> FEATURES = List.of(
+           new Feature("ProtocolRPCV2CBOR", (model, service) -> service.hasTrait(Rpcv2CborTrait.class))
+    );
+
+    @Override
+    public List<RuntimeClientPlugin> getClientPlugins() {
+        return FEATURES.stream().map(Feature::getPlugin).toList();
+    }
+
+    @Override
+    public void writeAdditionalFiles(GoCodegenContext ctx) {
+        var model = ctx.model();
+        var service = ctx.settings().getService(model);
+        ctx.writerDelegator().useFileWriter("api_client.go", ctx.settings().getModuleName(),
+                GoWriter.ChainWritable.of(
+                        FEATURES.stream()
+                                .filter(it -> it.servicePredicate.test(model, service))
+                                .map(Feature::getAddMiddleware)
+                                .toList()
+                ).compose());
+    }
+
+    private static final class Feature {
+        public final Symbol featureId;
+        public final BiPredicate<Model, ServiceShape> servicePredicate;
+
+        public Feature(String id, BiPredicate<Model, ServiceShape> servicePredicate) {
+            this.featureId = AwsGoDependency.AWS_MIDDLEWARE.constSymbol("UserAgentFeature" + id);
+            this.servicePredicate = servicePredicate;
+        }
+
+        public RuntimeClientPlugin getPlugin() {
+            return RuntimeClientPlugin.builder()
+                    .servicePredicate(servicePredicate)
+                    .registerMiddleware(
+                            MiddlewareRegistrar.builder()
+                                    .resolvedFunction(buildPackageSymbol("add" + featureId.getName()))
+                                    .useClientOptions()
+                                    .build()
+                    )
+                    .build();
+        }
+
+        public GoWriter.Writable getAddMiddleware() {
+            return goTemplate("""
+                    func add$featureName:L(stack $stack:P, options Options) error {
+                        ua, err := getOrAddRequestUserAgent(stack)
+                        if err != nil {
+                            return err
+                        }
+
+                        ua.AddUserAgentFeature($featureEnum:T)
+                        return nil
+                    }
+                    """,
+                    Map.of(
+                            "stack", SmithyGoTypes.Middleware.Stack,
+                            "featureName", featureId.getName(),
+                            "featureEnum", featureId
+                    ));
+        }
+    }
+}

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

@@ -85,3 +85,4 @@ software.amazon.smithy.aws.go.codegen.customization.RetryModeUserAgent
 software.amazon.smithy.aws.go.codegen.customization.RequestCompressionUserAgent
 software.amazon.smithy.aws.go.codegen.customization.s3.ExpressUserAgent
 software.amazon.smithy.aws.go.codegen.customization.BackfillRequiredTrait
+software.amazon.smithy.aws.go.codegen.customization.BasicUserAgentFeatures