Move to TOML configuration for plugin configurations

Makefile

@@ -105,11 +105,11 @@ $(STAGING_DIR):
 	@install "$(BUILD_BIN_DIR)/container" "$(join $(STAGING_DIR), bin/container)"
 	@install "$(BUILD_BIN_DIR)/container-apiserver" "$(join $(STAGING_DIR), bin/container-apiserver)"
 	@install "$(BUILD_BIN_DIR)/container-runtime-linux" "$(join $(STAGING_DIR), libexec/container/plugins/container-runtime-linux/bin/container-runtime-linux)"
-	@install Sources/Plugins/RuntimeLinux/config.json "$(join $(STAGING_DIR), libexec/container/plugins/container-runtime-linux/config.json)"
+	@install Sources/Plugins/RuntimeLinux/config.toml "$(join $(STAGING_DIR), libexec/container/plugins/container-runtime-linux/config.toml)"
 	@install "$(BUILD_BIN_DIR)/container-network-vmnet" "$(join $(STAGING_DIR), libexec/container/plugins/container-network-vmnet/bin/container-network-vmnet)"
-	@install Sources/Plugins/NetworkVmnet/config.json "$(join $(STAGING_DIR), libexec/container/plugins/container-network-vmnet/config.json)"
+	@install Sources/Plugins/NetworkVmnet/config.toml "$(join $(STAGING_DIR), libexec/container/plugins/container-network-vmnet/config.toml)"
 	@install "$(BUILD_BIN_DIR)/container-core-images" "$(join $(STAGING_DIR), libexec/container/plugins/container-core-images/bin/container-core-images)"
-	@install Sources/Plugins/CoreImages/config.json "$(join $(STAGING_DIR), libexec/container/plugins/container-core-images/config.json)"
+	@install Sources/Plugins/CoreImages/config.toml "$(join $(STAGING_DIR), libexec/container/plugins/container-core-images/config.toml)"
 
 	@echo Install update script
 	@install scripts/update-container.sh "$(join $(STAGING_DIR), bin/update-container.sh)"

Package.swift

@@ -57,6 +57,7 @@ let package = Package(
         .package(url: "https://github.com/grpc/grpc-swift.git", from: "1.26.0"),
         .package(url: "https://github.com/swift-server/async-http-client.git", from: "1.20.1"),
         .package(url: "https://github.com/swiftlang/swift-docc-plugin.git", from: "1.1.0"),
+        .package(url: "https://github.com/mattt/swift-toml.git", from: "2.0.0"),
     ],
     targets: [
         .executableTarget(
@@ -219,7 +220,7 @@ let package = Package(
                 "ContainerXPC",
             ],
             path: "Sources/Plugins/CoreImages",
-            exclude: ["config.json"]
+            exclude: ["config.toml"]
         ),
         .target(
             name: "ContainerImagesService",
@@ -268,7 +269,7 @@ let package = Package(
                 "ContainerXPC",
             ],
             path: "Sources/Plugins/NetworkVmnet",
-            exclude: ["config.json"]
+            exclude: ["config.toml"]
         ),
         .target(
             name: "ContainerNetworkService",
@@ -318,7 +319,7 @@ let package = Package(
                 "ContainerXPC",
             ],
             path: "Sources/Plugins/RuntimeLinux",
-            exclude: ["config.json"]
+            exclude: ["config.toml"]
         ),
         .target(
             name: "ContainerSandboxService",
@@ -388,6 +389,7 @@ let package = Package(
                 .product(name: "Logging", package: "swift-log"),
                 .product(name: "ContainerizationOS", package: "containerization"),
                 .product(name: "SystemPackage", package: "swift-system"),
+                .product(name: "TOML", package: "swift-toml"),
                 "ContainerVersion",
             ]
         ),

Sources/APIServer/APIServer+Start.swift

@@ -200,8 +200,8 @@ extension APIServer {
             ].compactMap { $0 }
 
             let pluginFactories: [PluginFactory] = [
-                DefaultPluginFactory(),
-                AppBundlePluginFactory(),
+                DefaultPluginFactory(logger: log),
+                AppBundlePluginFactory(logger: log),
             ]
 
             for pluginDirectory in pluginDirectories {

Sources/ContainerCommands/Application.swift

@@ -162,8 +162,8 @@ public struct Application: AsyncLoggableCommand {
         ].compactMap { $0 }
 
         let pluginFactories: [any PluginFactory] = [
-            DefaultPluginFactory(),
-            AppBundlePluginFactory(),
+            DefaultPluginFactory(logger: bootstrapLogger),
+            AppBundlePluginFactory(logger: bootstrapLogger),
         ]
 
         guard let systemHealth = try? await ClientHealthCheck.ping(timeout: .seconds(10)) else {

Sources/ContainerPlugin/PluginConfig.swift

@@ -16,19 +16,20 @@
 
 //
 import Foundation
+import TOML
 
 /// PluginConfig details all of the fields to describe and register a plugin.
 /// A plugin is registered by creating a subdirectory  `<application-root>/user-plugins`,
 /// where the name of the subdirectory is the name of the plugin, and then placing a
-/// file named `config.json` inside with the schema below.
-/// If `services` is filled in then there MUST be a binary named  matching the plugin name
-/// in a `bin` subdirectory inside the same directory as the `config.json`.
-/// An example of a valid plugin directory structure would be
+/// file named `config.toml` (or fall back to the legacy `config.json` file) inside with
+/// the schema below. If `services` is filled in then there MUST be a binary named
+/// matching the plugin name in a `bin` subdirectory inside the same directory as
+/// the `config.toml`. An example of a valid plugin directory structure would be
 /// $ tree foobar
 /// foobar
 /// ├── bin
 /// │   └── foobar
-/// └── config.json
+/// └── config.toml (`config.json`)
 public struct PluginConfig: Sendable, Codable {
     /// Categories of services that can be offered through plugins.
     public enum DaemonPluginType: String, Sendable, Codable {
@@ -93,13 +94,21 @@ public struct PluginConfig: Sendable, Codable {
     /// Services configuration. Specify nil for a CLI plugin, and an empty array for
     /// that does not publish any XPC services.
     public let servicesConfig: ServicesConfig?
+
+    public init(abstract: String, author: String?, servicesConfig: ServicesConfig?) {
+        self.abstract = abstract
+        self.author = author
+        self.servicesConfig = servicesConfig
+    }
 }
 
 extension PluginConfig {
     public var isCLI: Bool { self.servicesConfig == nil }
 }
 
 extension PluginConfig {
+    /// Initialize from a config file, selecting the decoder based on file extension.
+    /// Supports `.toml` (via TOMLDecoder) and `.json` (via JSONDecoder).
     public init?(configURL: URL) throws {
         let fm = FileManager.default
         if !fm.fileExists(atPath: configURL.path) {
@@ -110,7 +119,16 @@ extension PluginConfig {
             return nil
         }
 
-        let decoder: JSONDecoder = JSONDecoder()
-        self = try decoder.decode(PluginConfig.self, from: data)
+        switch configURL.pathExtension {
+        case "toml":
+            guard let content = String(data: data, encoding: .utf8) else {
+                return nil
+            }
+            self = try TOMLDecoder().decode(PluginConfig.self, from: content)
+        case "json":
+            self = try JSONDecoder().decode(PluginConfig.self, from: data)
+        default:
+            return nil
+        }
     }
 }

Sources/ContainerPlugin/PluginFactory.swift

@@ -15,8 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-
-private let configFilename: String = "config.json"
+import Logging
 
 /// Describes the configuration and binary file locations for a plugin.
 public protocol PluginFactory: Sendable {
@@ -28,13 +27,36 @@ public protocol PluginFactory: Sendable {
 
 /// Default layout which uses a Unix-like structure.
 public struct DefaultPluginFactory: PluginFactory {
-    public init() {}
+    // Order matters: earlier entries take priority during config file discovery.
+    private static let configFilenames: [String] = ["config.toml", "config.json"]
+    private let logger: Logger
+
+    public init(logger: Logger) {
+        self.logger = logger
+    }
+
+    /// Returns the URL of the first config file found in `directory`, preferring TOML over JSON.
+    static func findConfigURL(in directory: URL, logger: Logger) -> URL? {
+        let fm = FileManager.default
+        for filename in configFilenames {
+            let url = directory.appending(path: filename)
+            if fm.fileExists(atPath: url.path) {
+                if url.pathExtension == "json" {
+                    logger.warning(
+                        "Plugin using legacy config.json; please migrate to config.toml",
+                        metadata: ["path": "\(url.path)"]
+                    )
+                }
+                return url
+            }
+        }
+        return nil
+    }
 
     public func create(installURL: URL) throws -> Plugin? {
         let fm = FileManager.default
 
-        let configURL = installURL.appending(path: configFilename)
-        guard fm.fileExists(atPath: configURL.path) else {
+        guard let configURL = Self.findConfigURL(in: installURL, logger: logger) else {
             return nil
         }
 
@@ -63,18 +85,21 @@ public struct DefaultPluginFactory: PluginFactory {
 /// Layout which uses a macOS application bundle structure.
 public struct AppBundlePluginFactory: PluginFactory {
     private static let appSuffix = ".app"
+    private let logger: Logger
 
-    public init() {}
+    public init(logger: Logger) {
+        self.logger = logger
+    }
 
     public func create(installURL: URL) throws -> Plugin? {
         let fm = FileManager.default
 
-        let configURL =
+        let contentResources =
             installURL
             .appending(path: "Contents")
             .appending(path: "Resources")
-            .appending(path: configFilename)
-        guard fm.fileExists(atPath: configURL.path) else {
+
+        guard let configURL = DefaultPluginFactory.findConfigURL(in: contentResources, logger: logger) else {
             return nil
         }
 
@@ -96,11 +121,6 @@ public struct AppBundlePluginFactory: PluginFactory {
             return nil
         }
 
-        let contentResources =
-            installURL
-            .appending(path: "Contents")
-            .appending(path: "Resources")
-
         var resourceURL: URL? = nil
         if case let url = contentResources.appending(path: "resources"), fm.fileExists(atPath: url.path) {
             resourceURL = url

Sources/Plugins/CoreImages/config.toml

@@ -0,0 +1,12 @@
+abstract = "Core image management plugin"
+author = "Apple"
+version = 0.1
+
+[servicesConfig]
+loadAtBoot = true
+runAtLoad = false
+defaultArguments = []
+
+[[servicesConfig.services]]
+type = "core"
+description = "Provide an XPC interface to interact with an image store."

Sources/Plugins/NetworkVmnet/config.toml

@@ -0,0 +1,11 @@
+abstract = "vmnet network management plugin"
+author = "Apple"
+version = 0.1
+
+[servicesConfig]
+loadAtBoot = false
+runAtLoad = true
+defaultArguments = []
+
+[[servicesConfig.services]]
+type = "network"

Sources/Plugins/RuntimeLinux/config.toml

@@ -0,0 +1,11 @@
+abstract = "Linux container runtime plugin"
+author = "Apple"
+version = 0.1
+
+[servicesConfig]
+loadAtBoot = false
+runAtLoad = false
+defaultArguments = []
+
+[[servicesConfig.services]]
+type = "runtime"