Add new system status command (#118)

Container services can be started and stopped using the `system start`
and `system stop` commands. But there is no straightforward way for
users to check if the services were already started.

This PR adds a new `system status` command that shows wether the
container services are running or not.

The command only checks the status of the apiserver for now, but it
could be expanded in the future to show more details.

Fixes #117.

Author: gonzolino

Sources/CLI/System/SystemCommand.swift

@@ -27,6 +27,7 @@ extension Application {
                 SystemRestart.self,
                 SystemStart.self,
                 SystemStop.self,
+                SystemStatus.self,
                 SystemKernel.self,
             ],
             aliases: ["s"]

Sources/CLI/System/SystemStatus.swift

@@ -0,0 +1,52 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the container project 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
+//
+//   https://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 ArgumentParser
+import ContainerClient
+import ContainerPlugin
+import ContainerizationError
+import Foundation
+import Logging
+
+extension Application {
+    struct SystemStatus: AsyncParsableCommand {
+        static let configuration = CommandConfiguration(
+            commandName: "status",
+            abstract: "Show the status of `container` services"
+        )
+
+        @Option(name: .shortAndLong, help: "Launchd prefix for `container` services")
+        var prefix: String = "com.apple.container."
+
+        func run() async throws {
+            let isRegistered = try ServiceManager.isRegistered(fullServiceLabel: "\(prefix)apiserver")
+            if !isRegistered {
+                print("apiserver is not running and not registered with launchd")
+                Application.exit(withError: ExitCode(1))
+            }
+
+            // Now ping our friendly daemon. Fail after 10 seconds with no response.
+            do {
+                print("Verifying apiserver is running...")
+                try await ClientHealthCheck.ping(timeout: .seconds(10))
+                print("apiserver is running")
+            } catch {
+                print("apiserver is not running")
+                Application.exit(withError: ExitCode(1))
+            }
+        }
+    }
+}