Add GRPCServiceLifecycle module (#29)

This new module adds conformances to the `Service` protocol from
`grpc-swift-service-lifecycle` to `GRPCClient` and `GRPCServer` so that
they compose nicely with `ServiceLifecycle`.

*Note: depends on grpc/grpc-swift#2166

Author: gjcairo

Package.swift

@@ -30,6 +30,10 @@ let products: [Product] = [
     name: "GRPCInterceptors",
     targets: ["GRPCInterceptors"]
   ),
+  .library(
+    name: "GRPCServiceLifecycle",
+    targets: ["GRPCServiceLifecycle"]
+  ),
   .library(
     name: "GRPCInteropTests",
     targets: ["GRPCInteropTests"]
@@ -39,7 +43,7 @@ let products: [Product] = [
 let dependencies: [Package.Dependency] = [
   .package(
     url: "https://github.com/grpc/grpc-swift.git",
-    exact: "2.0.0-beta.3"
+    branch: "main"
   ),
   .package(
     url: "https://github.com/grpc/grpc-swift-protobuf.git",
@@ -53,6 +57,10 @@ let dependencies: [Package.Dependency] = [
     url: "https://github.com/apple/swift-distributed-tracing.git",
     from: "1.1.2"
   ),
+  .package(
+    url: "https://github.com/swift-server/swift-service-lifecycle.git",
+    from: "2.6.3"
+  ),
 ]
 
 let defaultSwiftSettings: [SwiftSetting] = [
@@ -126,6 +134,26 @@ let targets: [Target] = [
     swiftSettings: defaultSwiftSettings
   ),
 
+  // Retroactive conformances of gRPC client and server to swift-server-lifecycle's Service.
+  .target(
+    name: "GRPCServiceLifecycle",
+    dependencies: [
+      .product(name: "GRPCCore", package: "grpc-swift"),
+      .product(name: "ServiceLifecycle", package: "swift-service-lifecycle"),
+    ],
+    swiftSettings: defaultSwiftSettings
+  ),
+  .testTarget(
+    name: "GRPCServiceLifecycleTests",
+    dependencies: [
+      .target(name: "GRPCServiceLifecycle"),
+      .product(name: "GRPCCore", package: "grpc-swift"),
+      .product(name: "ServiceLifecycleTestKit", package: "swift-service-lifecycle"),
+      .product(name: "GRPCInProcessTransport", package: "grpc-swift"),
+    ],
+    swiftSettings: defaultSwiftSettings
+  ),
+
   // gRPC interop test implementation.
   .target(
     name: "GRPCInteropTests",

Sources/GRPCServiceLifecycle/GRPCClient+Service.swift

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2025, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public import GRPCCore
+public import ServiceLifecycle
+
+// A `@retroactive` conformance here is okay because this project is also owned by the owners of
+// `GRPCCore`, and thus, the owners of `GRPCClient`. A conflicting conformance won't be added.
+extension GRPCClient: @retroactive Service {
+  public func run() async throws {
+    try await withGracefulShutdownHandler {
+      try await self.runConnections()
+    } onGracefulShutdown: {
+      self.beginGracefulShutdown()
+    }
+  }
+}

Sources/GRPCServiceLifecycle/GRPCServer+Service.swift

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2025, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public import GRPCCore
+public import ServiceLifecycle
+
+// A `@retroactive` conformance here is okay because this project is also owned by the owners of
+// `GRPCCore`, and thus, the owners of `GRPCServer`. A conflicting conformance won't be added.
+extension GRPCServer: @retroactive Service {
+  public func run() async throws {
+    try await withGracefulShutdownHandler {
+      try await self.serve()
+    } onGracefulShutdown: {
+      self.beginGracefulShutdown()
+    }
+  }
+}

Tests/GRPCServiceLifecycleTests/ServiceLifecycleConformanceTests.swift

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2025, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import GRPCCore
+import GRPCInProcessTransport
+import GRPCServiceLifecycle
+import ServiceLifecycleTestKit
+import Testing
+
+@Suite("gRPC ServiceLifecycle/Service conformance tests")
+struct ServiceLifecycleConformanceTests {
+  @Test("Client respects graceful shutdown")
+  func clientGracefulShutdown() async throws {
+    let inProcess = InProcessTransport()
+    try await testGracefulShutdown { trigger in
+      try await withThrowingDiscardingTaskGroup { group in
+        group.addTask {
+          let client = GRPCClient(transport: inProcess.client)
+          try await client.run()
+        }
+
+        group.addTask {
+          try await Task.sleep(for: .milliseconds(10))
+          trigger.triggerGracefulShutdown()
+        }
+      }
+    }
+  }
+
+  @Test("Server respects graceful shutdown")
+  func serverGracefulShutdown() async throws {
+    let inProcess = InProcessTransport()
+    try await testGracefulShutdown { trigger in
+      try await withThrowingDiscardingTaskGroup { group in
+        group.addTask {
+          let server = GRPCServer(transport: inProcess.server, services: [])
+          try await server.run()
+        }
+
+        group.addTask {
+          try await Task.sleep(for: .milliseconds(10))
+          trigger.triggerGracefulShutdown()
+        }
+      }
+    }
+  }
+}

Tests/InProcessInteropTests/InProcessInteroperabilityTests.swift

@@ -35,7 +35,7 @@ final class InProcessInteroperabilityTests: XCTestCase {
           try await withThrowingTaskGroup(of: Void.self) { clientGroup in
             let client = GRPCClient(transport: inProcess.client)
             clientGroup.addTask {
-              try await client.run()
+              try await client.runConnections()
             }
             try await interopTestCase.makeTest().run(client: client)