Use CRT by default when h2 is needed

codegen/smithy-python-codegen-test/model/main.smithy

@@ -8,7 +8,10 @@ use smithy.test#httpResponseTests
 use smithy.waiters#waitable
 
 /// Provides weather forecasts.
-@restJson1
+@restJson1(
+    http: ["h2", "http/1.1"]
+    eventStreamHttp: ["h2"]
+)
 @fakeProtocol
 @paginated(inputToken: "nextToken", outputToken: "nextToken", pageSize: "pageSize")
 @httpApiKeyAuth(name: "weather-auth", in: "header")

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/ApplicationProtocol.java

@@ -17,15 +17,20 @@
 
 import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.codegen.core.SymbolReference;
+import software.amazon.smithy.model.node.ObjectNode;
 import software.amazon.smithy.utils.SmithyUnstableApi;
 
 /**
  * Represents the resolves {@link Symbol}s and references for an
  * application protocol (e.g., "http", "mqtt", etc).
  */
 @SmithyUnstableApi
-public record ApplicationProtocol(String name, SymbolReference requestType, SymbolReference responseType) {
-
+public record ApplicationProtocol(
+        String name,
+        SymbolReference requestType,
+        SymbolReference responseType,
+        ObjectNode configuration
+) {
     /**
      * Checks if the protocol is an HTTP based protocol.
      *
@@ -40,18 +45,28 @@ public boolean isHttpProtocol() {
      *
      * @return Returns the created application protocol.
      */
-    public static ApplicationProtocol createDefaultHttpApplicationProtocol() {
+    public static ApplicationProtocol createDefaultHttpApplicationProtocol(ObjectNode config) {
         return new ApplicationProtocol(
                 "http",
                 SymbolReference.builder()
                         .symbol(createHttpSymbol("HTTPRequest"))
                         .build(),
                 SymbolReference.builder()
                         .symbol(createHttpSymbol("HTTPResponse"))
-                        .build()
+                        .build(),
+                config
         );
     }
 
+    /**
+     * Creates a default HTTP application protocol.
+     *
+     * @return Returns the created application protocol.
+     */
+    public static ApplicationProtocol createDefaultHttpApplicationProtocol() {
+        return createDefaultHttpApplicationProtocol(ObjectNode.objectNode());
+    }
+
     private static Symbol createHttpSymbol(String symbolName) {
         PythonDependency dependency = SmithyPythonDependency.SMITHY_HTTP;
         return Symbol.builder()

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/ConfigGenerator.java

@@ -20,9 +20,14 @@
 import java.util.Collection;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.model.knowledge.EventStreamIndex;
 import software.amazon.smithy.model.knowledge.ServiceIndex;
 import software.amazon.smithy.model.knowledge.TopDownIndex;
+import software.amazon.smithy.model.node.ArrayNode;
+import software.amazon.smithy.model.node.StringNode;
+import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.python.codegen.integration.PythonIntegration;
 import software.amazon.smithy.python.codegen.integration.RuntimeClientPlugin;
 import software.amazon.smithy.python.codegen.sections.ConfigSection;
@@ -65,23 +70,8 @@ final class ConfigGenerator implements Runnable {
     );
 
     // This list contains any properties that must be added to any http-based
-    // service client.
+    // service client, except for the http client itself.
     private static final List<ConfigProperty> HTTP_PROPERTIES = Arrays.asList(
-        ConfigProperty.builder()
-            .name("http_client")
-            .type(Symbol.builder()
-                .name("HTTPClient")
-                .namespace("smithy_http.aio.interfaces", ".")
-                .addDependency(SmithyPythonDependency.SMITHY_HTTP)
-                .build())
-            .documentation("The HTTP client used to make requests.")
-            .nullable(false)
-            .initialize(writer -> {
-                writer.addDependency(SmithyPythonDependency.SMITHY_HTTP);
-                writer.addImport("smithy_http.aio.aiohttp", "AIOHTTPClient");
-                writer.write("self.http_client = http_client or AIOHTTPClient()");
-            })
-            .build(),
         ConfigProperty.builder()
             .name("http_request_config")
             .type(Symbol.builder()
@@ -137,6 +127,64 @@ final class ConfigGenerator implements Runnable {
         this.settings = settings;
     }
 
+    private static List<ConfigProperty> getHttpProperties(GenerationContext context) {
+        var properties = new ArrayList<ConfigProperty>(HTTP_PROPERTIES.size() + 1);
+        var clientBuilder = ConfigProperty.builder()
+                .name("http_client")
+                .type(Symbol.builder()
+                        .name("HTTPClient")
+                        .namespace("smithy_http.aio.interfaces", ".")
+                        .addDependency(SmithyPythonDependency.SMITHY_HTTP)
+                        .build())
+                .documentation("The HTTP client used to make requests.")
+                .nullable(false);
+
+        if (usesHttp2(context)) {
+            clientBuilder
+                .initialize(writer -> {
+                    writer.addDependency(SmithyPythonDependency.SMITHY_HTTP.withOptionalDependencies("awscrt"));
+                    writer.addImport("smithy_http.aio.crt", "AWSCRTHTTPClient");
+                    writer.write("self.http_client = http_client or AWSCRTHTTPClient()");
+                });
+
+        } else {
+            clientBuilder
+                .initialize(writer -> {
+                    writer.addDependency(SmithyPythonDependency.SMITHY_HTTP.withOptionalDependencies("aiohttp"));
+                    writer.addImport("smithy_http.aio.aiohttp", "AIOHTTPClient");
+                    writer.write("self.http_client = http_client or AIOHTTPClient()");
+                });
+        }
+        properties.add(clientBuilder.build());
+
+        properties.addAll(HTTP_PROPERTIES);
+        return List.copyOf(properties);
+    }
+
+    private static boolean usesHttp2(GenerationContext context) {
+        var configuration = context.applicationProtocol().configuration();
+        var httpVersions = configuration.getArrayMember("http")
+                .orElse(ArrayNode.arrayNode())
+                .getElementsAs(StringNode.class)
+                .stream().map(node -> node.getValue().toLowerCase(Locale.ENGLISH)).toList();
+
+        // An explicit http2 configuration
+        if (httpVersions.contains("h2")) {
+            return true;
+        }
+
+        // Bidirectional streaming REQUIRES h2 inherently
+        var eventIndex = EventStreamIndex.of(context.model());
+        var topDownIndex = TopDownIndex.of(context.model());
+        for (OperationShape operation : topDownIndex.getContainedOperations(context.settings().service())) {
+            if (eventIndex.getInputInfo(operation).isPresent() && eventIndex.getOutputInfo(operation).isPresent()) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private static List<ConfigProperty> getHttpAuthProperties(GenerationContext context) {
         return List.of(
             ConfigProperty.builder()
@@ -254,7 +302,7 @@ private void generateConfig(GenerationContext context, PythonWriter writer) {
         // and add them in if the protocol is going to need them.
         var serviceIndex = ServiceIndex.of(context.model());
         if (context.applicationProtocol().isHttpProtocol()) {
-            properties.addAll(HTTP_PROPERTIES);
+            properties.addAll(getHttpProperties(context));
             if (!serviceIndex.getAuthSchemes(settings.service()).isEmpty()) {
                 properties.addAll(getHttpAuthProperties(context));
                 writer.onSection(new AddAuthHelper());

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/GenerationContext.java

@@ -96,7 +96,7 @@ public ProtocolGenerator protocolGenerator() {
      */
     public ApplicationProtocol applicationProtocol() {
         return protocolGenerator != null
-                ? protocolGenerator.getApplicationProtocol()
+                ? protocolGenerator.getApplicationProtocol(this)
                 : ApplicationProtocol.createDefaultHttpApplicationProtocol();
     }
 

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/PythonDependency.java

@@ -56,6 +56,10 @@ public SymbolDependency getDependency() {
                 .build();
     }
 
+    public PythonDependency withOptionalDependencies(String... optionalDependencies) {
+        return new PythonDependency(packageName, version, type, isLink, List.of(optionalDependencies));
+    }
+
     /**
      * An enum of valid dependency types.
      */

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/SmithyPythonDependency.java

@@ -49,9 +49,7 @@ public final class SmithyPythonDependency {
             // You'll need to locally install this before we publish
             "==0.0.1",
             Type.DEPENDENCY,
-            false,
-            // TODO: make this configurable
-            List.of("aiohttp")
+            false
     );
 
     /**

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/integration/HttpBindingProtocolGenerator.java

@@ -92,7 +92,7 @@ public abstract class HttpBindingProtocolGenerator implements ProtocolGenerator
     private final Set<Shape> deserializingDocumentShapes = new TreeSet<>();
 
     @Override
-    public ApplicationProtocol getApplicationProtocol() {
+    public ApplicationProtocol getApplicationProtocol(GenerationContext context) {
         return ApplicationProtocol.createDefaultHttpApplicationProtocol();
     }
 

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/integration/ProtocolGenerator.java

@@ -55,7 +55,7 @@ default String getName() {
      *
      * @return Returns the created application protocol.
      */
-    ApplicationProtocol getApplicationProtocol();
+    ApplicationProtocol getApplicationProtocol(GenerationContext context);
 
 
     /**

codegen/smithy-python-codegen/src/main/java/software/amazon/smithy/python/codegen/integration/RestJsonProtocolGenerator.java

@@ -19,6 +19,8 @@
 import java.util.Set;
 import software.amazon.smithy.aws.traits.protocols.RestJson1Trait;
 import software.amazon.smithy.model.knowledge.HttpBinding;
+import software.amazon.smithy.model.node.ArrayNode;
+import software.amazon.smithy.model.node.ObjectNode;
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.Shape;
@@ -27,6 +29,7 @@
 import software.amazon.smithy.model.traits.StreamingTrait;
 import software.amazon.smithy.model.traits.TimestampFormatTrait.Format;
 import software.amazon.smithy.protocoltests.traits.HttpMessageTestCase;
+import software.amazon.smithy.python.codegen.ApplicationProtocol;
 import software.amazon.smithy.python.codegen.CodegenUtils;
 import software.amazon.smithy.python.codegen.GenerationContext;
 import software.amazon.smithy.python.codegen.HttpProtocolTestGenerator;
@@ -90,6 +93,17 @@ public ShapeId getProtocol() {
         return RestJson1Trait.ID;
     }
 
+    @Override
+    public ApplicationProtocol getApplicationProtocol(GenerationContext context) {
+        var service = context.settings().service(context.model());
+        var trait = service.expectTrait(RestJson1Trait.class);
+        var config = ObjectNode.builder()
+                .withMember("http", ArrayNode.fromStrings(trait.getHttp()))
+                .withMember("eventStreamHttp", ArrayNode.fromStrings(trait.getEventStreamHttp()))
+                .build();
+        return ApplicationProtocol.createDefaultHttpApplicationProtocol(config);
+    }
+
     @Override
     protected Format getDocumentTimestampFormat() {
         return Format.EPOCH_SECONDS;