Examples: Adopt structure used in the Vapor template repository (#85)

Motivation
----------

The [Vapor template repository](https://github.com/vapor/template-bare)
splits the server into a main entry point file and a separate route
installation function. Adopting the same structure makes this example
more familiar to users who are used to the official template.

Fixes #61 

Modifications
-------------

* Adopt the Vapor template structure for `HelloWorldVapor`
* Use the `-warnings-as-errors` flag when building end to end examples.

Result
------

The example works in the same way as before but has a more familiar
structure for Vapor users.

Test Plan
---------

All tests continue to pass.

Author: euanh

.github/workflows/endtoend_tests.yml

@@ -44,6 +44,7 @@ jobs:
                   cat ${{ matrix.example }}/Package.swift
                   swift package \
                       --package-path ${{ matrix.example }} \
+                      -Xswiftc -warnings-as-errors \
                       --swift-sdk x86_64-swift-linux-musl \
                       --allow-network-connections all \
                       build-container-image \

Examples/HelloWorldVapor/Package.swift

@@ -20,8 +20,8 @@ let package = Package(
     name: "hello-world",
     platforms: [.macOS(.v13)],
     dependencies: [
-        .package(url: "https://github.com/vapor/vapor", .upToNextMajor(from: "4.102.0")),
-        .package(url: "https://github.com/apple/swift-container-plugin", from: "0.4.0"),
+        .package(url: "https://github.com/vapor/vapor", from: "4.102.0"),
+        .package(url: "https://github.com/apple/swift-container-plugin", from: "0.5.0"),
     ],
     targets: [.executableTarget(name: "hello-world", dependencies: [.product(name: "Vapor", package: "vapor")])]
 )

Examples/HelloWorldVapor/Sources/configure.swift

@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftContainerPlugin open source project
+//
+// Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftContainerPlugin project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Vapor
+
+func configure(_ app: Application) async throws {
+    try routes(app)
+}

Examples/HelloWorldVapor/Sources/entrypoint.swift

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftContainerPlugin open source project
+//
+// Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftContainerPlugin project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Vapor
+
+@main
+enum Entrypoint {
+    static func main() async throws {
+        let env = try Environment.detect()
+        let app = try await Application.make(env)
+        app.http.server.configuration.hostname = "0.0.0.0"
+
+        do {
+            try await configure(app)
+            try await app.execute()
+        } catch {
+            app.logger.report(error: error)
+            try? await app.asyncShutdown()
+            throw error
+        }
+        try await app.asyncShutdown()
+    }
+}

Examples/HelloWorldVapor/Sources/main.swift renamed to Examples/HelloWorldVapor/Sources/routes.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the SwiftContainerPlugin open source project
 //
-// Copyright (c) 2024 Apple Inc. and the SwiftContainerPlugin project authors
+// Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
 // Licensed under Apache License v2.0
 //
 // See LICENSE.txt for license information
@@ -17,10 +17,8 @@ import Vapor
 
 let myos = ProcessInfo.processInfo.operatingSystemVersionString
 
-let app = try Application(.detect())
-app.http.server.configuration.hostname = "0.0.0.0"
-defer { app.shutdown() }
-
-app.get { _ in "Hello World, from Vapor on \(myos)\n" }
-
-try app.run()
+func routes(_ app: Application) throws {
+    app.get { req async in
+        "Hello World, from Vapor on \(myos)\n"
+    }
+}