Add script to package and sign AppImages

This has not been tested yet at all.

Contributes to issue CURA-9409.

packaging/create_appimage.py

@@ -0,0 +1,58 @@
+# Copyright (c) 2022 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
+import os  # Finding installation directory.
+import os.path  # Finding files.
+import shutil  # Copying files.
+import stat  # For setting file permissions.
+import subprocess  # For calling system commands.
+
+dist_path = os.getcwd()  # TODO: Figure out where this is.
+appimage_filename = "Ultimaker-Cura_test.AppImage"  # TODO: Get the proper file name.
+
+def build_appimage():
+    """
+    Creates an AppImage file from the build artefacts created so far.
+    """
+    copy_metadata_files()
+
+    try:
+        shutil.rmtree(os.path.join(dist_path, appimage_filename))  # Ensure any old file is removed, if it exists.
+    except FileNotFoundError:
+        pass  # If it didn't exist, that's even better.
+
+    generate_appimage()
+
+    sign_appimage()
+
+def copy_metadata_files():
+    """
+    Copy metadata files for the metadata of the AppImage.
+    """
+    copied_files = {
+        "cura-icon_256x256.png": "cura-icon.png",
+        "cura.desktop": "cura.desktop",
+        "cura.appdata.xml": "cura.appdata.xml",
+        "AppRun": "AppRun"
+    }
+
+    packaging_dir = os.path.dirname(__file__)
+    for source, dest in copied_files.items():
+        shutil.copyfile(os.path.join(packaging_dir, source), os.path.join(dist_path, dest))
+
+    # Ensure that AppRun has the proper permissions: 755 (user reads, writes and executes, group reads and executes, world reads and executes).
+    os.chmod(os.path.join(dist_path, "AppRun"), stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)
+
+def generate_appimage():
+    appimage_path = os.path.join(dist_path, appimage_filename)
+    command = ["appimagetool", "--appimage-extract-and-run", f"{dist_path}/", appimage_path]
+    result = subprocess.call(*command)
+    if result != 0:
+        raise RuntimeError(f"The AppImageTool command returned non-zero: {result}")
+
+def sign_appimage():
+    appimage_path = os.path.join(dist_path, appimage_filename)
+    command = ["gpg", "--yes", "--armor", "--detach-sig", {appimage_path}]
+    result = subprocess.call(*command)
+    if result != 0:
+        raise RuntimeError(f"The GPG command returned non-zero: {result}")