Set the default arguments passed to the entrypoint

Plugins/ContainerImageBuilder/main.swift

@@ -99,8 +99,8 @@ extension PluginError: CustomStringConvertible {
         let helperURL = try context.tool(named: "containertool").url
         let helperArgs =
             (FileManager.default.fileExists(atPath: resources.path) ? ["--resources", resources.path] : [])
-            + extractor.remainingArguments
             + builtExecutables.map { $0.url.path }
+            + extractor.remainingArguments
         let helperEnv = ProcessInfo.processInfo.environment.filter { $0.key.starts(with: "CONTAINERTOOL_") }
 
         let err = Pipe()

Sources/containertool/Extensions/RegistryClient+publish.swift

@@ -25,6 +25,7 @@ func publishContainerImage<Source: ImageSource, Destination: ImageDestination>(
     destination: Destination,
     architecture: String,
     os: String,
+    cmd: [String],
     resources: [String],
     tag: String?,
     verbose: Bool,
@@ -80,7 +81,7 @@ func publishContainerImage<Source: ImageSource, Destination: ImageDestination>(
     // and override the entrypoint.
     var inheritedConfiguration = baseImageConfiguration.config ?? .init()
     inheritedConfiguration.Entrypoint = ["/\(executableURL.lastPathComponent)"]
-    inheritedConfiguration.Cmd = []
+    inheritedConfiguration.Cmd = cmd
     inheritedConfiguration.WorkingDir = "/"
 
     let configuration = ImageConfiguration(

Sources/containertool/containertool.swift

@@ -64,6 +64,9 @@ enum AllowHTTP: String, ExpressibleByArgument, CaseIterable { case source, desti
 
         @Option(help: "Operating system")
         var os: String?
+
+        @Option(parsing: .remaining, help: "Default arguments to pass to the entrypoint process")
+        var cmd: [String] = []
     }
 
     @OptionGroup(title: "Image configuration options")
@@ -222,6 +225,7 @@ enum AllowHTTP: String, ExpressibleByArgument, CaseIterable { case source, desti
             destination: destination,
             architecture: architecture,
             os: os,
+            cmd: imageConfigurationOptions.cmd,
             resources: imageBuildOptions.resources,
             tag: repositoryOptions.tag,
             verbose: verbose,

Sources/swift-container-plugin/Documentation.docc/build-container-image.md

@@ -56,6 +56,10 @@ Wrap a binary in a container image and publish it.
 - term  `--os <os>`:
   Operating system required to run the image. (default: `linux`)
 
+- term  `--cmd <cmd1> <cmd2> …`:
+  Default arguments to pass to the entrypoint process.
+  This MUST be the last option present as all following arguments are considered part of the CMD entry. 
+
 ### Authentication options
 
 - term  `--default-username <username>`:

scripts/test-containertool-cmd.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+##===----------------------------------------------------------------------===##
+##
+## This source file is part of the SwiftContainerPlugin open source project
+##
+## Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
+## Licensed under Apache License v2.0
+##
+## See LICENSE.txt for license information
+## See CONTRIBUTORS.txt for the list of SwiftContainerPlugin project authors
+##
+## SPDX-License-Identifier: Apache-2.0
+##
+##===----------------------------------------------------------------------===##
+
+#
+# This script assumes that the Static Linux SDK has already been installed
+#
+
+log() { printf -- "** %s\n" "$*" >&2; }
+error() { printf -- "** ERROR: %s\n" "$*" >&2; }
+fatal() { error "$@"; exit 1; }
+
+set -euo pipefail
+
+RUNTIME=${RUNTIME-"docker"}
+
+#
+# Create a test package
+#
+PKGPATH=$(mktemp -d)
+swift package --package-path "$PKGPATH" init --type executable --name hello
+
+cleanup() {
+  log "Deleting temporary package $PKGPATH"
+  rm -rf "$PKGPATH"
+}
+trap cleanup EXIT
+
+#
+# Build and package an aarch64 binary
+#
+swift build --package-path "$PKGPATH" --swift-sdk aarch64-swift-linux-musl
+
+IMGREF=$(swift run containertool --repository localhost:5000/elf_test "$PKGPATH/.build/aarch64-swift-linux-musl/debug/hello" --from scratch --cmd "arg1" "--option" "opt" "--flag")
+$RUNTIME pull "$IMGREF"
+CMD=$($RUNTIME inspect "$IMGREF" --format "{{.Config.Cmd}}")
+if [ "$CMD" = "[arg1 --option opt --flag]" ] ; then
+  log "cmd option: PASSED"
+else
+  fatal "cmd option: FAILED - cmd was $CMD; expected [arg1 --option opt --flag]"
+fi