installer: T7102: download upgrade images to a random path in the roo…

…t filesystem

src/op_mode/image_installer.py

@@ -99,7 +99,7 @@
 DIR_DST_ROOT: str = f'{DIR_INSTALLATION}/disk_dst'
 DIR_KERNEL_SRC: str = '/boot/'
 FILE_ROOTFS_SRC: str = '/usr/lib/live/mount/medium/live/filesystem.squashfs'
-ISO_DOWNLOAD_PATH: str = '/tmp/vyos_installation.iso'
+ISO_DOWNLOAD_PATH: str = ''
 
 external_download_script = '/usr/libexec/vyos/simple-download.py'
 external_latest_image_url_script = '/usr/libexec/vyos/latest-image-url.py'
@@ -552,6 +552,11 @@ def image_fetch(image_path: str, vrf: str = None,
     Returns:
         Path: a path to a local file
     """
+    import os.path
+    from uuid import uuid4
+
+    global ISO_DOWNLOAD_PATH
+
     # Latest version gets url from configured "system update-check url"
     if image_path == 'latest':
         command = external_latest_image_url_script
@@ -568,6 +573,7 @@ def image_fetch(image_path: str, vrf: str = None,
         # check a type of path
         if urlparse(image_path).scheme:
             # download an image
+            ISO_DOWNLOAD_PATH = os.path.join(os.path.expanduser("~"), '{0}.iso'.format(uuid4()))
             download_file(ISO_DOWNLOAD_PATH, image_path, vrf,
                           username, password,
                           progressbar=True, check_space=True)