Build services with a derived configuration object (#3095)

This is a pared-down version of #2809.

This is the code-generated version of the
david-perez/smithy-rs-service-config#2 POC.

This introduces a code-generated `PokemonServiceConfig` object which is
provided to the service builder constructor via
`PokemonService::builder(config: PokemonServiceConfig)`. This will
displace the
current `builder_without_plugins` and `builder_with_plugins`,
deprecating them.
We will eventually remove them.

The motivation is to have a single place where to register plugins and
layers.
Smithy traits can leverage this object to inject methods that can apply
plugins
and layers. For example, an `@authorization` trait implementer could
vend a
smithy-rs decorator that pre-applied an authorization plugin inside the
`${serviceName}Config` object, possibly exposing a method to pass in any
runtime arguments needed to configure the middleware.

## Checklist
- [x] I have updated `CHANGELOG.next.toml` if I made changes to the
smithy-rs codegen or runtime crates

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

CHANGELOG.next.toml

@@ -506,3 +506,9 @@ The [`connection`](https://docs.rs/aws-smithy-http/latest/aws_smithy_http/connec
 references = ["smithy-rs#3092", "smithy-rs#3093"]
 meta = { "breaking" = true, "tada" = false, "bug" = false, "target" = "client" }
 author = "ysaito1001"
+
+[[smithy-rs]]
+message = "Service builder initialization now takes in a `${serviceName}Config` object on which plugins and layers should be registered. The `builder_with_plugins` and `builder_without_plugins` methods on the service builder, as well as the `layer` method on the built service have been deprecated, and will be removed in a future release. See the [upgrade guidance](https://github.com/awslabs/smithy-rs/discussions/3096) for more details."
+references = ["smithy-rs#3095", "smithy-rs#3096"]
+meta = { "breaking" = true, "tada" = false, "bug" = true, "target" = "server" }
+author = "david-perez"

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/rustlang/RustWriter.kt

@@ -551,10 +551,7 @@ class RustWriter private constructor(
         if (this.className.contains("AbstractCodeWriter") || this.className.startsWith("java.lang")) {
             return false
         }
-        if (this.fileName == "RustWriter.kt") {
-            return false
-        }
-        return true
+        return this.fileName != "RustWriter.kt"
     }
 
     private val preamble = mutableListOf<Writable>()

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/ServerCodegenVisitor.kt

@@ -73,6 +73,7 @@ import software.amazon.smithy.rust.codegen.server.smithy.generators.ServerRootGe
 import software.amazon.smithy.rust.codegen.server.smithy.generators.ServerRuntimeTypesReExportsGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.generators.ServerServiceGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.generators.ServerStructureConstrainedTraitImpl
+import software.amazon.smithy.rust.codegen.server.smithy.generators.ServiceConfigGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.generators.UnconstrainedCollectionGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.generators.UnconstrainedMapGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.generators.UnconstrainedUnionGenerator
@@ -590,29 +591,31 @@ open class ServerCodegenVisitor(
         logger.info("[rust-server-codegen] Generating a service $shape")
         val serverProtocol = protocolGeneratorFactory.protocol(codegenContext) as ServerProtocol
 
-        // Generate root
+        // Generate root.
         rustCrate.lib {
             ServerRootGenerator(
                 serverProtocol,
                 codegenContext,
             ).render(this)
         }
 
-        // Generate server re-exports
+        // Generate server re-exports.
         rustCrate.withModule(ServerRustModule.Server) {
             ServerRuntimeTypesReExportsGenerator(codegenContext).render(this)
         }
 
-        // Generate protocol tests
+        // Generate protocol tests.
         protocolTests()
 
-        // Generate service module
+        // Generate service module.
         rustCrate.withModule(ServerRustModule.Service) {
             ServerServiceGenerator(
                 codegenContext,
                 serverProtocol,
             ).render(this)
 
+            ServiceConfigGenerator(codegenContext).render(this)
+
             ScopeMacroGenerator(codegenContext).render(this)
         }
     }

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/ServerRootGenerator.kt

@@ -73,9 +73,9 @@ open class ServerRootGenerator(
             //! ```rust,no_run
             //! ## use std::net::SocketAddr;
             //! ## async fn dummy() {
-            //! use $crateName::$serviceName;
+            //! use $crateName::{$serviceName, ${serviceName}Config};
             //!
-            //! ## let app = $serviceName::builder_without_plugins().build_unchecked();
+            //! ## let app = $serviceName::builder(${serviceName}Config::builder().build()).build_unchecked();
             //! let server = app.into_make_service();
             //! let bind: SocketAddr = "127.0.0.1:6969".parse()
             //!     .expect("unable to parse the server bind address and port");
@@ -92,36 +92,34 @@ open class ServerRootGenerator(
             //! use $crateName::$serviceName;
             //!
             //! ## async fn dummy() {
-            //! ## let app = $serviceName::builder_without_plugins().build_unchecked();
+            //! ## let app = $serviceName::builder(${serviceName}Config::builder().build()).build_unchecked();
             //! let handler = LambdaHandler::new(app);
             //! lambda_http::run(handler).await.unwrap();
             //! ## }
             //! ```
             //!
             //! ## Building the $serviceName
             //!
-            //! To construct [`$serviceName`] we use [`$builderName`] returned by [`$serviceName::builder_without_plugins`]
-            //! or [`$serviceName::builder_with_plugins`].
+            //! To construct [`$serviceName`] we use [`$builderName`] returned by [`$serviceName::builder`].
             //!
             //! #### Plugins
             //!
-            //! The [`$serviceName::builder_with_plugins`] method, returning [`$builderName`],
-            //! accepts a plugin marked with [`HttpMarker`](aws_smithy_http_server::plugin::HttpMarker) and a
-            //! plugin marked with [`ModelMarker`](aws_smithy_http_server::plugin::ModelMarker).
+            //! The [`$serviceName::builder`] method, returning [`$builderName`],
+            //! accepts a config object on which plugins can be registered.
             //! Plugins allow you to build middleware which is aware of the operation it is being applied to.
             //!
-            //! ```rust
-            //! ## use #{SmithyHttpServer}::plugin::IdentityPlugin;
+            //! ```rust,no_run
             //! ## use #{SmithyHttpServer}::plugin::IdentityPlugin as LoggingPlugin;
             //! ## use #{SmithyHttpServer}::plugin::IdentityPlugin as MetricsPlugin;
             //! ## use #{Hyper}::Body;
             //! use #{SmithyHttpServer}::plugin::HttpPlugins;
-            //! use $crateName::{$serviceName, $builderName};
+            //! use $crateName::{$serviceName, ${serviceName}Config, $builderName};
             //!
             //! let http_plugins = HttpPlugins::new()
             //!         .push(LoggingPlugin)
             //!         .push(MetricsPlugin);
-            //! let builder: $builderName<Body, _, _> = $serviceName::builder_with_plugins(http_plugins, IdentityPlugin);
+            //! let config = ${serviceName}Config::builder().build();
+            //! let builder: $builderName<Body, _, _, _> = $serviceName::builder(config);
             //! ```
             //!
             //! Check out [`#{SmithyHttpServer}::plugin`] to learn more about plugins.
@@ -136,7 +134,7 @@ open class ServerRootGenerator(
             //! * A `Result<Output, Error>` if your operation has modeled errors, or
             //! * An `Output` otherwise.
             //!
-            //! ```rust
+            //! ```rust,no_run
             //! ## struct Input;
             //! ## struct Output;
             //! ## struct Error;
@@ -147,7 +145,7 @@ open class ServerRootGenerator(
             //!
             //! Handlers can accept up to 8 extractors:
             //!
-            //! ```rust
+            //! ```rust,no_run
             //! ## struct Input;
             //! ## struct Output;
             //! ## struct Error;
@@ -187,11 +185,12 @@ open class ServerRootGenerator(
             //!
             //! ```rust
             //! ## use std::net::SocketAddr;
-            //! use $crateName::$serviceName;
+            //! use $crateName::{$serviceName, ${serviceName}Config};
             //!
             //! ##[#{Tokio}::main]
             //! pub async fn main() {
-            //!    let app = $serviceName::builder_without_plugins()
+            //!    let config = ${serviceName}Config::builder().build();
+            //!    let app = $serviceName::builder(config)
             ${builderFieldNames.values.joinToString("\n") { "//!        .$it($it)" }}
             //!        .build()
             //!        .expect("failed to build an instance of $serviceName");
@@ -237,6 +236,6 @@ open class ServerRootGenerator(
     fun render(rustWriter: RustWriter) {
         documentation(rustWriter)
 
-        rustWriter.rust("pub use crate::service::{$serviceName, ${serviceName}Builder, MissingOperationsError};")
+        rustWriter.rust("pub use crate::service::{$serviceName, ${serviceName}Config, ${serviceName}ConfigBuilder, ${serviceName}Builder, MissingOperationsError};")
     }
 }