Add server example

Examples/server/.devcontainer/devcontainer.json

@@ -0,0 +1,52 @@
+{
+  "name": "Server",
+  "workspaceFolder": "/workspace/server",
+  "dockerComposeFile": [
+    "../docker-compose.yaml",
+    "docker-compose.yaml"
+  ],
+  "service": "server",
+  "runServices": [
+    "flipt",
+    "jaeger",
+    "otel-collector",
+    "server"
+  ],
+  "shutdownAction": "stopCompose",
+  "features": {
+    "ghcr.io/devcontainers/features/common-utils:2": {
+      "installZsh": "false",
+      "username": "server",
+      "upgradePackages": "false"
+    },
+    "ghcr.io/devcontainers/features/git:1": {
+      "version": "os-provided",
+      "ppa": "false"
+    }
+  },
+  "customizations": {
+    "vscode": {
+      "settings": {
+        "lldb.library": "/usr/lib/liblldb.so",
+        "swift.autoGenerateLaunchConfigurations": false
+      },
+      "extensions": [
+        "swiftlang.swift-vscode"
+      ]
+    }
+  },
+  "forwardPorts": [8080, 8081, 16686],
+  "portsAttributes": {
+    "8080": {
+      "label": "API",
+      "onAutoForward": "notify"
+    },
+    "8081": {
+      "label": "Flipt"
+    },
+    "16686": {
+      "label": "Jaeger"
+    }
+  },
+  "remoteUser": "server"
+}

Examples/server/.devcontainer/docker-compose.yaml

@@ -0,0 +1,6 @@
+services:
+  server:
+    image: swift:6.1
+    command: sleep infinity
+    volumes:
+      - ..:/workspace:cached

Examples/server/Package.swift

@@ -0,0 +1,50 @@
+// swift-tools-version:6.0
+import PackageDescription
+
+let package = Package(
+    name: "server",
+    platforms: [.macOS(.v15)],
+    products: [
+        .executable(name: "server", targets: ["CTL"])
+    ],
+    dependencies: [
+        .package(url: "https://github.com/swift-server/swift-service-lifecycle.git", from: "2.0.0"),
+        .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
+        .package(url: "https://github.com/apple/swift-distributed-tracing.git", from: "1.0.0"),
+        .package(url: "https://github.com/swift-otel/swift-otel.git", .upToNextMinor(from: "0.11.0")),
+        .package(url: "https://github.com/hummingbird-project/hummingbird.git", from: "2.0.0"),
+        .package(url: "https://github.com/hummingbird-project/hummingbird-auth.git", from: "2.0.0"),
+        .package(url: "https://github.com/swift-open-feature/swift-open-feature.git", branch: "main"),
+        .package(url: "https://github.com/swift-open-feature/swift-ofrep.git", branch: "main"),
+
+        // override HTTP Client until Tracing PR is merged
+        .package(url: "https://github.com/slashmo/async-http-client.git", branch: "feature/tracing"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "CTL",
+            dependencies: [
+                .target(name: "API"),
+                .product(name: "ServiceLifecycle", package: "swift-service-lifecycle"),
+                .product(name: "Logging", package: "swift-log"),
+                .product(name: "Tracing", package: "swift-distributed-tracing"),
+                .product(name: "OTel", package: "swift-otel"),
+                .product(name: "OTLPGRPC", package: "swift-otel"),
+                .product(name: "Hummingbird", package: "hummingbird"),
+                .product(name: "OpenFeature", package: "swift-open-feature"),
+                .product(name: "OpenFeatureTracing", package: "swift-open-feature"),
+                .product(name: "OFREP", package: "swift-ofrep"),
+            ]
+        ),
+        .target(
+            name: "API",
+            dependencies: [
+                .product(name: "ServiceLifecycle", package: "swift-service-lifecycle"),
+                .product(name: "Logging", package: "swift-log"),
+                .product(name: "Hummingbird", package: "hummingbird"),
+                .product(name: "HummingbirdAuth", package: "hummingbird-auth"),
+                .product(name: "OpenFeature", package: "swift-open-feature"),
+            ]
+        ),
+    ]
+)

Examples/server/README.md

@@ -0,0 +1,3 @@
+# Swift OFREP server example
+
+An HTTP server that can be altered at runtime using feature flags powered by Swift OFREP.

Examples/server/Sources/API/APIService.swift

@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Hummingbird
+import OpenFeature
+import ServiceLifecycle
+
+public struct APIService: Service {
+    private let app: Application<RouterResponder<APIRequestContext>>
+    private let client: OpenFeatureClient
+
+    public init(router: Router<APIRequestContext>) {
+        client = OpenFeatureSystem.client()
+
+        router
+            .addMiddleware {
+                AuthMiddleware()
+                EvaluationContextMiddleware()
+            }
+            .addRoutes(FeedController().routes)
+
+        app = Application(router: router)
+    }
+
+    public func run() async throws {
+        try await app.run()
+    }
+}

Examples/server/Sources/API/AuthMiddleware.swift

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import HTTPTypes
+import Hummingbird
+import HummingbirdAuth
+
+struct AuthMiddleware: AuthenticatorMiddleware {
+    typealias Context = APIRequestContext
+
+    func authenticate(request: Request, context: APIRequestContext) async throws -> User? {
+        guard let userID = request.headers[.userID] else { return nil }
+        return User(id: userID)
+    }
+}
+
+extension HTTPField.Name {
+    fileprivate static let userID = Self("X-User-Id")!
+}

Examples/server/Sources/API/EvaluationContextMiddleware.swift

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Hummingbird
+import OpenFeature
+
+struct EvaluationContextMiddleware: MiddlewareProtocol {
+    func handle(
+        _ request: Request,
+        context: APIRequestContext,
+        next: (Request, APIRequestContext) async throws -> Response
+    ) async throws -> Response {
+        var evaluationContext = OpenFeatureEvaluationContext.current ?? OpenFeatureEvaluationContext()
+        evaluationContext.targetingKey = context.identity?.id
+        return try await OpenFeatureEvaluationContext.$current.withValue(evaluationContext) {
+            try await next(request, context)
+        }
+    }
+}

Examples/server/Sources/API/FeedController.swift

@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Hummingbird
+import OpenFeature
+
+struct FeedController {
+    private let featureFlags: OpenFeatureClient
+
+    init() {
+        featureFlags = OpenFeatureSystem.client()
+    }
+
+    var routes: RouteCollection<APIRequestContext> {
+        let routes = RouteCollection(context: APIRequestContext.self)
+        routes.get(use: list)
+        return routes
+    }
+
+    private func list(request: Request, context: APIRequestContext) async throws -> Feed {
+        let useNewFeedAlgorithm = await featureFlags.value(for: "experimental-feed-algorithm", defaultingTo: false)
+
+        if useNewFeedAlgorithm {
+            // the new algorithm is faster but unfortunately still contains some bugs
+            if UInt.random(in: 0..<100) == 42 {
+                throw HTTPError(.internalServerError)
+            }
+            try await Task.sleep(for: .seconds(1))
+            return Feed.stub
+        } else {
+            try await Task.sleep(for: .seconds(2))
+            return Feed.stub
+        }
+    }
+}
+
+struct Feed: ResponseCodable {
+    let posts: [Post]
+
+    struct Post: ResponseCodable {
+        let id: String
+    }
+
+    static let stub = Feed(posts: [
+        Post(id: "1"),
+        Post(id: "2"),
+        Post(id: "3"),
+    ])
+}

Examples/server/Sources/API/RequestContext.swift

@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Hummingbird
+import HummingbirdAuth
+
+public struct APIRequestContext: AuthRequestContext, Sendable {
+    public var coreContext: CoreRequestContextStorage
+    public var identity: User?
+
+    public init(source: ApplicationRequestContextSource) {
+        coreContext = .init(source: source)
+    }
+}

Examples/server/Sources/API/User.swift

@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift OpenFeature open source project
+//
+// Copyright (c) 2025 the Swift OpenFeature project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+public struct User: Identifiable, Sendable {
+    public let id: String
+}