add help option on archiver plugin

Author: sebsto

Plugins/AWSLambdaPackager/Plugin.swift

@@ -12,14 +12,20 @@
 //
 //===----------------------------------------------------------------------===//
 
-import PackagePlugin
 import Foundation
+import PackagePlugin
 
 @main
 @available(macOS 15.0, *)
 struct AWSLambdaPackager: CommandPlugin {
     func performCommand(context: PackagePlugin.PluginContext, arguments: [String]) async throws {
         let configuration = try Configuration(context: context, arguments: arguments)
+
+        if configuration.help {
+            self.displayHelpMessage()
+            return
+        }
+
         guard !configuration.products.isEmpty else {
             throw Errors.unknownProduct("no appropriate products found to package")
         }
@@ -112,7 +118,9 @@ struct AWSLambdaPackager: CommandPlugin {
         guard let buildPathOutput = dockerBuildOutputPath.split(separator: "\n").last else {
             throw Errors.failedParsingDockerOutput(dockerBuildOutputPath)
         }
-        let buildOutputPath = URL(string: buildPathOutput.replacingOccurrences(of: "/workspace/", with: packageDirectory.description))!            
+        let buildOutputPath = URL(
+            string: buildPathOutput.replacingOccurrences(of: "/workspace/", with: packageDirectory.description)
+        )!
 
         // build the products
         var builtProducts = [LambdaProduct: URL]()
@@ -126,7 +134,7 @@ struct AWSLambdaPackager: CommandPlugin {
                 // just like Package.swift's examples assume ../.., we assume we are two levels below the root project
                 let slice = packageDirectory.pathComponents.suffix(2)
                 let beforeLastComponent = packageDirectory.pathComponents[slice.startIndex]
-                let lastComponent = packageDirectory.pathComponents[slice.endIndex-1]
+                let lastComponent = packageDirectory.pathComponents[slice.endIndex - 1]
                 try Utils.execute(
                     executable: dockerToolPath,
                     arguments: [
@@ -270,10 +278,47 @@ struct AWSLambdaPackager: CommandPlugin {
             return false
         }
     }
+
+    private func displayHelpMessage() {
+        print(
+            """
+            OVERVIEW: A SwiftPM plugin to build and package your lambda function.
+
+            REQUIREMENTS: To use this plugin, you must have docker installed and started.
+
+            USAGE: swift package --disable-sandbox archive [--help] [--verbose]
+                                                       [--output-directory <path>]
+                                                       [--products <list of products>]
+                                                       [--configuration debug | release]
+                                                       [--swift-version <version>]
+                                                       [--base-docker-image <docker_image_name>]
+                                                       [--disable-docker-image-update]
+                                                      
+
+            OPTIONS:
+            --verbose                     Produce verbose output for debugging.
+            --output-directory <path>     The path of the binary package.
+                                          (default is `.build/plugins/AWSLambdaPackager/outputs/...`)
+            --products <list>             The list of executable targets to build.
+                                          (default is taken from Package.swift)
+            --configuration <name>        The build configuration (debug or release)
+                                          (default is release)
+            --swift-version               The swift version to use for building. 
+                                          (default is latest)
+                                          This parameter cannot be used when --base-docker-image  is specified.
+            --base-docker-image <name>    The name of the base docker image to use for the build.
+                                          (default : swift-<version>:amazonlinux2)
+                                          This parameter cannot be used when --swift-version is specified.
+            --disable-docker-image-update Do not attempt to update the docker image
+            --help                        Show help information.
+            """
+        )
+    }
 }
 
 @available(macOS 15.0, *)
 private struct Configuration: CustomStringConvertible {
+    public let help: Bool
     public let outputDirectory: URL
     public let products: [Product]
     public let explicitProducts: Bool
@@ -294,15 +339,20 @@ private struct Configuration: CustomStringConvertible {
         let swiftVersionArgument = argumentExtractor.extractOption(named: "swift-version")
         let baseDockerImageArgument = argumentExtractor.extractOption(named: "base-docker-image")
         let disableDockerImageUpdateArgument = argumentExtractor.extractFlag(named: "disable-docker-image-update") > 0
+        let helpArgument = argumentExtractor.extractFlag(named: "help") > 0
 
+        // help required ?
+        self.help = helpArgument
+
+        // verbose logging required ?
         self.verboseLogging = verboseArgument
 
         if let outputPath = outputPathArgument.first {
             #if os(Linux)
             var isDirectory: Bool = false
             #else
             var isDirectory: ObjCBool = false
-            #endif 
+            #endif
             guard FileManager.default.fileExists(atPath: outputPath, isDirectory: &isDirectory)
             else {
                 throw Errors.invalidArgument("invalid output directory '\(outputPath)'")
@@ -447,7 +497,9 @@ private struct LambdaProduct: Hashable {
 extension PackageManager.BuildResult {
     // find the executable produced by the build
     func executableArtifact(for product: Product) -> PackageManager.BuildResult.BuiltArtifact? {
-        let executables = self.builtArtifacts.filter { $0.kind == .executable && $0.url.lastPathComponent == product.name }
+        let executables = self.builtArtifacts.filter {
+            $0.kind == .executable && $0.url.lastPathComponent == product.name
+        }
         guard !executables.isEmpty else {
             return nil
         }