feat: add interceptor client config

Allows configuration of interceptors on a client level by adding interceptor
providers to client config, allowing Plugins to add interceptors.

The primary addition is `InterceptorProvider`, an interface that creates
generic interceptors which can operate on any transport - http or otherwise.
When an operation is executed, interceptor providers are called to create
new instances of service-level interceptors. Creating new instances also
means we don't need to synchronize on the shared interceptors. Transport
specific config, have their own methods for adding interceptor providers, so
you can add `HttpInterceptorProvider`s to http config. Operations know which
transport they operate on, and can choose which transport-specific interceptor
providers to use.

If/when we have operation-level configuration, it might make more sense to
allow plugins to configure more generic 'operation customizations' or
something, rather than just the interceptors. Operations would then call
the customizations before executing.

A few other minor changes were made to the client libraries:
- Added actual builder methods to RequestMessageBuilder, which we would need
eventually, so I could use them in testing
- Made SdkHttpRequestBuilder final

Codegen was also updated to generate the new config methods, and to call
interceptor providers in operations to add configured interceptors.

Sources/ClientRuntime/Config/DefaultClientConfiguration.swift

@@ -29,5 +29,10 @@ public protocol DefaultClientConfiguration: ClientConfiguration {
     /// If none is provided, only a default logger provider will be used.
     var telemetryProvider: TelemetryProvider { get set }
 
+    /// Add an `InterceptorProvider` that will be used to provide interceptors for all operations.
+    ///
+    /// - Parameter provider: The `InterceptorProvider` to add.
+    func addInterceptorProvider(_ provider: InterceptorProvider)
+
     /// TODO(plugins): Add Checksum, etc.
 }

Sources/ClientRuntime/Config/DefaultHttpClientConfiguration.swift

@@ -25,4 +25,9 @@ public protocol DefaultHttpClientConfiguration: ClientConfiguration {
     ///
     /// Defaults to a auth scheme resolver generated based on Smithy service model.
     var authSchemeResolver: ClientRuntime.AuthSchemeResolver { get set }
+
+    /// Add an `HttpInterceptorProvider` that will be used to provide interceptors for all HTTP operations.
+    ///
+    /// - Parameter provider: The `HttpInterceptorProvider` to add.
+    func addInterceptorProvider(_ provider: HttpInterceptorProvider)
 }

Sources/ClientRuntime/Interceptor/HttpInterceptorProvider.swift

@@ -0,0 +1,17 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+/// Provides implementations of `HttpInterceptor`.
+///
+/// For the generic counterpart, see `InterceptorProvider`.
+public protocol HttpInterceptorProvider {
+
+    /// Creates an instance of an `HttpInterceptor` implementation.
+    ///
+    /// - Returns: The `HttpInterceptor` implementation.
+    func create<InputType, OutputType>() -> any HttpInterceptor<InputType, OutputType>
+}

Sources/ClientRuntime/Interceptor/InterceptorProvider.swift

@@ -0,0 +1,25 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+/// Provides implementations of `Interceptor` for any Request, Response, and Attributes types.
+///
+/// This can be used to create `Interceptor`s that are generic on their Request/Response/Attributes
+/// types, when you don't have access to the exact types until later.
+public protocol InterceptorProvider {
+
+    /// Creates an instance of an `Interceptor` implementation, specialized on the given
+    /// `RequestType`, `ResponseType`, and `AttributesType`.
+    ///
+    /// - Returns: The `Interceptor` implementation.
+    func create<
+        InputType,
+        OutputType,
+        RequestType: RequestMessage,
+        ResponseType: ResponseMessage,
+        AttributesType: HasAttributes
+    >() -> any Interceptor<InputType, OutputType, RequestType, ResponseType, AttributesType>
+}

Sources/ClientRuntime/Interceptor/Interceptors.swift

@@ -26,6 +26,13 @@ public struct Interceptors<
         self.interceptors.append(interceptor.erase())
     }
 
+    /// - Parameter interceptor: The Interceptor to add.
+    public mutating func add(
+        _ interceptor: some Interceptor<InputType, OutputType, RequestType, ResponseType, AttributesType>
+    ) {
+        self.interceptors.append(interceptor.erase())
+    }
+
     /// - Parameter interceptorFn: The closure to use as the Interceptor hook.
     public mutating func addReadBeforeExecution(
         _ interceptorFn: @escaping (any BeforeSerialization<InputType, AttributesType>) async throws -> Void

Sources/ClientRuntime/Message/RequestMessageBuilder.swift

@@ -13,6 +13,10 @@ public protocol RequestMessageBuilder<RequestType>: AnyObject {
 
     init()
 
+    func withHost(_ host: String) -> Self
+
+    func withBody(_ body: ByteStream) -> Self
+
     /// - Returns: The built request.
     func build() -> RequestType
 }

Sources/ClientRuntime/Networking/Http/SdkHttpRequest.swift

@@ -189,7 +189,7 @@ extension SdkHttpRequestBuilder {
     }
 }
 
-public class SdkHttpRequestBuilder: RequestMessageBuilder {
+public final class SdkHttpRequestBuilder: RequestMessageBuilder {
 
     required public init() {}
 

Sources/WeatherSDK/WeatherClient.swift

@@ -44,9 +44,13 @@ extension WeatherClient {
 
         public var authSchemeResolver: ClientRuntime.AuthSchemeResolver
 
+        public private(set) var interceptorProviders: [ClientRuntime.InterceptorProvider]
+
+        public private(set) var httpInterceptorProviders: [ClientRuntime.HttpInterceptorProvider]
+
         internal let logger: ClientRuntime.LogAgent
 
-        private init(_ telemetryProvider: ClientRuntime.TelemetryProvider, _ retryStrategyOptions: ClientRuntime.RetryStrategyOptions, _ clientLogMode: ClientRuntime.ClientLogMode, _ endpoint: Swift.String?, _ idempotencyTokenGenerator: ClientRuntime.IdempotencyTokenGenerator, _ httpClientEngine: ClientRuntime.HTTPClient, _ httpClientConfiguration: ClientRuntime.HttpClientConfiguration, _ authSchemes: [ClientRuntime.AuthScheme]?, _ authSchemeResolver: ClientRuntime.AuthSchemeResolver) {
+        private init(_ telemetryProvider: ClientRuntime.TelemetryProvider, _ retryStrategyOptions: ClientRuntime.RetryStrategyOptions, _ clientLogMode: ClientRuntime.ClientLogMode, _ endpoint: Swift.String?, _ idempotencyTokenGenerator: ClientRuntime.IdempotencyTokenGenerator, _ httpClientEngine: ClientRuntime.HTTPClient, _ httpClientConfiguration: ClientRuntime.HttpClientConfiguration, _ authSchemes: [ClientRuntime.AuthScheme]?, _ authSchemeResolver: ClientRuntime.AuthSchemeResolver, _ interceptorProviders: [ClientRuntime.InterceptorProvider], _ httpInterceptorProviders: [ClientRuntime.HttpInterceptorProvider]) {
             self.telemetryProvider = telemetryProvider
             self.retryStrategyOptions = retryStrategyOptions
             self.clientLogMode = clientLogMode
@@ -56,20 +60,30 @@ extension WeatherClient {
             self.httpClientConfiguration = httpClientConfiguration
             self.authSchemes = authSchemes
             self.authSchemeResolver = authSchemeResolver
+            self.interceptorProviders = interceptorProviders
+            self.httpInterceptorProviders = httpInterceptorProviders
             self.logger = telemetryProvider.loggerProvider.getLogger(name: WeatherClient.clientName)
         }
 
-        public convenience init(telemetryProvider: ClientRuntime.TelemetryProvider? = nil, retryStrategyOptions: ClientRuntime.RetryStrategyOptions? = nil, clientLogMode: ClientRuntime.ClientLogMode? = nil, endpoint: Swift.String? = nil, idempotencyTokenGenerator: ClientRuntime.IdempotencyTokenGenerator? = nil, httpClientEngine: ClientRuntime.HTTPClient? = nil, httpClientConfiguration: ClientRuntime.HttpClientConfiguration? = nil, authSchemes: [ClientRuntime.AuthScheme]? = nil, authSchemeResolver: ClientRuntime.AuthSchemeResolver? = nil) throws {
-            self.init(telemetryProvider ?? ClientRuntime.DefaultTelemetry.provider, retryStrategyOptions ?? ClientConfigurationDefaults.defaultRetryStrategyOptions, clientLogMode ?? ClientConfigurationDefaults.defaultClientLogMode, endpoint, idempotencyTokenGenerator ?? ClientConfigurationDefaults.defaultIdempotencyTokenGenerator, httpClientEngine ?? ClientConfigurationDefaults.makeClient(httpClientConfiguration: httpClientConfiguration ?? ClientConfigurationDefaults.defaultHttpClientConfiguration), httpClientConfiguration ?? ClientConfigurationDefaults.defaultHttpClientConfiguration, authSchemes, authSchemeResolver ?? ClientConfigurationDefaults.defaultAuthSchemeResolver)
+        public convenience init(telemetryProvider: ClientRuntime.TelemetryProvider? = nil, retryStrategyOptions: ClientRuntime.RetryStrategyOptions? = nil, clientLogMode: ClientRuntime.ClientLogMode? = nil, endpoint: Swift.String? = nil, idempotencyTokenGenerator: ClientRuntime.IdempotencyTokenGenerator? = nil, httpClientEngine: ClientRuntime.HTTPClient? = nil, httpClientConfiguration: ClientRuntime.HttpClientConfiguration? = nil, authSchemes: [ClientRuntime.AuthScheme]? = nil, authSchemeResolver: ClientRuntime.AuthSchemeResolver? = nil, interceptorProviders: [ClientRuntime.InterceptorProvider]? = nil, httpInterceptorProviders: [ClientRuntime.HttpInterceptorProvider]? = nil) throws {
+            self.init(telemetryProvider ?? ClientRuntime.DefaultTelemetry.provider, retryStrategyOptions ?? ClientConfigurationDefaults.defaultRetryStrategyOptions, clientLogMode ?? ClientConfigurationDefaults.defaultClientLogMode, endpoint, idempotencyTokenGenerator ?? ClientConfigurationDefaults.defaultIdempotencyTokenGenerator, httpClientEngine ?? ClientConfigurationDefaults.makeClient(httpClientConfiguration: httpClientConfiguration ?? ClientConfigurationDefaults.defaultHttpClientConfiguration), httpClientConfiguration ?? ClientConfigurationDefaults.defaultHttpClientConfiguration, authSchemes, authSchemeResolver ?? ClientConfigurationDefaults.defaultAuthSchemeResolver, interceptorProviders ?? [], httpInterceptorProviders ?? [])
         }
 
         public convenience required init() async throws {
-            try await self.init(telemetryProvider: nil, retryStrategyOptions: nil, clientLogMode: nil, endpoint: nil, idempotencyTokenGenerator: nil, httpClientEngine: nil, httpClientConfiguration: nil, authSchemes: nil, authSchemeResolver: nil)
+            try await self.init(telemetryProvider: nil, retryStrategyOptions: nil, clientLogMode: nil, endpoint: nil, idempotencyTokenGenerator: nil, httpClientEngine: nil, httpClientConfiguration: nil, authSchemes: nil, authSchemeResolver: nil, interceptorProviders: nil, httpInterceptorProviders: nil)
         }
 
         public var partitionID: String? {
             return ""
         }
+        public func addInterceptorProvider(_ provider: ClientRuntime.InterceptorProvider) {
+            self.interceptorProviders.append(provider)
+        }
+
+        public func addInterceptorProvider(_ provider: ClientRuntime.HttpInterceptorProvider) {
+            self.httpInterceptorProviders.append(provider)
+        }
+
     }
 
     public static func builder() -> ClientBuilder<WeatherClient> {

Tests/ClientRuntimeTests/InterceptorTests/InterceptorTests.swift

@@ -65,8 +65,9 @@ class InterceptorTests: XCTestCase {
         }
     }
 
-    struct ModifyMultipleInterceptor<OutputType>: HttpInterceptor {
+    struct ModifyMultipleInterceptor: HttpInterceptor {
         public typealias InputType = TestInput
+        public typealias OutputType = TestOutput
 
         private let newInputValue: Int
 
@@ -95,7 +96,7 @@ class InterceptorTests: XCTestCase {
         let addAttributeInterceptor = AddAttributeInterceptor<String, TestInput, TestOutput, SdkHttpRequest, HttpResponse, HttpContext>(key: AttributeKey(name: "foo"), value: "bar")
         let modifyInputInterceptor = ModifyInputInterceptor<TestInput, TestOutput, SdkHttpRequest, HttpResponse, HttpContext>(keyPath: \.property, value: "bar")
         let addHeaderInterceptor = AddHeaderInterceptor<TestInput, TestOutput>(headerName: "foo", headerValue: "bar")
-        let modifyMultipleInterceptor = ModifyMultipleInterceptor<TestOutput>(newInputValue: 1)
+        let modifyMultipleInterceptor = ModifyMultipleInterceptor(newInputValue: 1)
 
         let interceptors: [AnyInterceptor<TestInput, TestOutput, SdkHttpRequest, HttpResponse, HttpContext>] = [
             addAttributeInterceptor.erase(),
@@ -118,4 +119,37 @@ class InterceptorTests: XCTestCase {
         XCTAssertEqual(interceptorContext.getRequest().headers.value(for: "foo"), "bar")
         XCTAssertEqual(interceptorContext.getRequest().headers.value(for: "otherProperty"), "1")
     }
+
+    struct ModifyHostInterceptor<InputType, OutputType, RequestType: RequestMessage, ResponseType: ResponseMessage, AttributesType: HasAttributes>: Interceptor {
+        func modifyBeforeRetryLoop(context: some MutableRequest<Self.InputType, Self.RequestType, Self.AttributesType>) async throws {
+            context.updateRequest(updated: context.getRequest().toBuilder().withHost("foo").build())
+        }
+    }
+
+    struct ModifyHostInterceptorProvider: InterceptorProvider {
+        func create<InputType, OutputType, RequestType: RequestMessage, ResponseType: ResponseMessage, AttributesType: HasAttributes>() -> any Interceptor<InputType, OutputType, RequestType, ResponseType, AttributesType> {
+            ModifyHostInterceptor()
+        }
+    }
+
+    func test_providers() async throws {
+        let provider1 = ModifyHostInterceptorProvider()
+        var interceptors = Interceptors<TestInput, TestOutput, SdkHttpRequest, HttpResponse, HttpContext>()
+
+        interceptors.add(provider1.create())
+
+        let httpContext = HttpContext(attributes: Attributes())
+        let input = TestInput()
+
+        let context = DefaultInterceptorContext<TestInput, TestOutput, SdkHttpRequest, HttpResponse, HttpContext>(input: input, attributes: httpContext)
+        context.updateRequest(updated: SdkHttpRequestBuilder().build())
+
+        try await interceptors.modifyBeforeSerialization(context: context)
+        try await interceptors.modifyBeforeRetryLoop(context: context)
+        try await interceptors.modifyBeforeTransmit(context: context)
+
+        let resultRequest = try XCTUnwrap(context.getRequest())
+
+        XCTAssertEqual(resultRequest.host, "foo")
+    }
 }

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/ClientRuntimeTypes.kt

@@ -76,6 +76,18 @@ object ClientRuntimeTypes {
         val AuthSchemeResolverParams = runtimeSymbol("AuthSchemeResolverParameters")
     }
 
+    object Interceptor {
+        val Provider = runtimeSymbol("InterceptorProvider")
+        val Providers = runtimeSymbolWithoutNamespace("[ClientRuntime.InterceptorProvider]")
+        val HttpProvider = runtimeSymbolWithoutNamespace("ClientRuntime.HttpInterceptorProvider")
+        val HttpProviders = runtimeSymbolWithoutNamespace("[ClientRuntime.HttpInterceptorProvider]")
+    }
+
+    object Operation {
+        val Orchestrator = runtimeSymbol("Orchestrator")
+        val OrchestratorBuilder = runtimeSymbol("OrchestratorBuilder")
+    }
+
     object Core {
         val Endpoint = runtimeSymbol("Endpoint")
         val Date = runtimeSymbol("Date")

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/config/ClientConfiguration.kt

@@ -8,6 +8,7 @@ package software.amazon.smithy.swift.codegen.config
 import software.amazon.smithy.codegen.core.Symbol
 import software.amazon.smithy.swift.codegen.Dependency
 import software.amazon.smithy.swift.codegen.integration.ProtocolGenerator
+import software.amazon.smithy.swift.codegen.lang.Function
 import software.amazon.smithy.swift.codegen.model.buildSymbol
 
 /**
@@ -21,6 +22,11 @@ interface ClientConfiguration {
 
     fun getProperties(ctx: ProtocolGenerator.GenerationContext): Set<ConfigProperty>
 
+    /**
+     * The methods to render in the generated client configuration
+     */
+    fun getMethods(ctx: ProtocolGenerator.GenerationContext): Set<Function> = setOf()
+
     companion object {
         fun runtimeSymbol(
             name: String,

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/config/ConfigProperty.kt

@@ -6,23 +6,31 @@
 package software.amazon.smithy.swift.codegen.config
 
 import software.amazon.smithy.codegen.core.Symbol
+import software.amazon.smithy.swift.codegen.SwiftWriter
+import software.amazon.smithy.swift.codegen.lang.AccessModifier
 import software.amazon.smithy.swift.codegen.model.isOptional
 
 data class ConfigProperty(
     val name: String,
     val type: Symbol,
-    val default: DefaultProvider? = null
+    val default: DefaultProvider? = null,
+    val accessModifier: AccessModifier = AccessModifier.Public,
 ) {
     constructor(
         name: String,
         type: Symbol,
         default: String,
         isThrowable: Boolean = false,
-        isAsync: Boolean = false
-    ) : this(name, type, DefaultProvider(default, isThrowable, isAsync))
+        isAsync: Boolean = false,
+        accessModifier: AccessModifier = AccessModifier.Public
+    ) : this(name, type, DefaultProvider(default, isThrowable, isAsync), accessModifier)
 
     init {
         if (!type.isOptional() && default == null)
             throw RuntimeException("Non-optional client config property must have a default value")
     }
+
+    fun render(writer: SwiftWriter) {
+        writer.write("${accessModifier.renderedRightPad()}var \$L: \$N", name, type)
+    }
 }

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/config/DefaultClientConfiguration.kt

@@ -11,6 +11,9 @@ import software.amazon.smithy.swift.codegen.SwiftDependency
 import software.amazon.smithy.swift.codegen.SwiftTypes
 import software.amazon.smithy.swift.codegen.config.ClientConfiguration.Companion.runtimeSymbol
 import software.amazon.smithy.swift.codegen.integration.ProtocolGenerator
+import software.amazon.smithy.swift.codegen.lang.AccessModifier
+import software.amazon.smithy.swift.codegen.lang.Function
+import software.amazon.smithy.swift.codegen.lang.FunctionParameter
 import software.amazon.smithy.swift.codegen.model.toOptional
 
 class DefaultClientConfiguration : ClientConfiguration {
@@ -39,5 +42,21 @@ class DefaultClientConfiguration : ClientConfiguration {
             ClientRuntimeTypes.Core.IdempotencyTokenGenerator,
             "ClientConfigurationDefaults.defaultIdempotencyTokenGenerator"
         ),
+        ConfigProperty(
+            "interceptorProviders",
+            ClientRuntimeTypes.Interceptor.Providers,
+            "[]",
+            accessModifier = AccessModifier.PublicPrivateSet
+        ),
+    )
+
+    override fun getMethods(ctx: ProtocolGenerator.GenerationContext): Set<Function> = setOf(
+        Function(
+            name = "addInterceptorProvider",
+            renderBody = { writer -> writer.write("self.interceptorProviders.append(provider)") },
+            parameters = listOf(
+                FunctionParameter.NoLabel("provider", ClientRuntimeTypes.Interceptor.Provider)
+            ),
+        )
     )
 }

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/config/DefaultHttpClientConfiguration.kt

@@ -10,6 +10,9 @@ import software.amazon.smithy.swift.codegen.ClientRuntimeTypes
 import software.amazon.smithy.swift.codegen.SwiftDependency
 import software.amazon.smithy.swift.codegen.config.ClientConfiguration.Companion.runtimeSymbol
 import software.amazon.smithy.swift.codegen.integration.ProtocolGenerator
+import software.amazon.smithy.swift.codegen.lang.AccessModifier
+import software.amazon.smithy.swift.codegen.lang.Function
+import software.amazon.smithy.swift.codegen.lang.FunctionParameter
 import software.amazon.smithy.swift.codegen.model.toOptional
 
 class DefaultHttpClientConfiguration : ClientConfiguration {
@@ -34,6 +37,22 @@ class DefaultHttpClientConfiguration : ClientConfiguration {
             "authSchemeResolver",
             ClientRuntimeTypes.Auth.AuthSchemeResolver,
             "ClientConfigurationDefaults.defaultAuthSchemeResolver"
+        ),
+        ConfigProperty(
+            "httpInterceptorProviders",
+            ClientRuntimeTypes.Interceptor.HttpProviders,
+            "[]",
+            accessModifier = AccessModifier.PublicPrivateSet
+        ),
+    )
+
+    override fun getMethods(ctx: ProtocolGenerator.GenerationContext): Set<Function> = setOf(
+        Function(
+            name = "addInterceptorProvider",
+            renderBody = { writer -> writer.write("self.httpInterceptorProviders.append(provider)") },
+            parameters = listOf(
+                FunctionParameter.NoLabel("provider", ClientRuntimeTypes.Interceptor.HttpProvider)
+            ),
         )
     )
 }

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/HttpProtocolServiceClient.kt

@@ -115,9 +115,11 @@ open class HttpProtocolServiceClient(
             serviceConfig.clientName.toUpperCamelCase(),
             clientConfigurationProtocols
         ) {
-            val properties: List<ConfigProperty> = ctx.integrations
-                .flatMap { it.clientConfigurations(ctx).flatMap { it.getProperties(ctx) } }
+            val clientConfigs = ctx.integrations.flatMap { it.clientConfigurations(ctx) }
+            val properties: List<ConfigProperty> = clientConfigs
+                .flatMap { it.getProperties(ctx) }
                 .let { overrideConfigProperties(it) }
+                .sortedBy { it.accessModifier }
 
             renderConfigClassVariables(serviceSymbol, properties)
 
@@ -132,6 +134,14 @@ open class HttpProtocolServiceClient(
             renderCustomConfigInitializer(properties)
 
             renderPartitionID()
+
+            clientConfigs
+                .flatMap { it.getMethods(ctx) }
+                .sortedBy { it.accessModifier }
+                .forEach {
+                    it.render(writer)
+                    writer.write("")
+                }
         }
         writer.write("")
     }
@@ -185,11 +195,10 @@ open class HttpProtocolServiceClient(
      * Declare class variables in client configuration class
      */
     private fun renderConfigClassVariables(serviceSymbol: Symbol, properties: List<ConfigProperty>) {
-        properties
-            .forEach {
-                writer.write("public var \$L: \$N", it.name, it.type)
-                writer.write("")
-            }
+        properties.forEach {
+            it.render(writer)
+            writer.write("")
+        }
         writer.injectSection(ConfigClassVariablesCustomization(serviceSymbol))
         writer.write("")
     }