3 files changed, 10 insertions, 5 deletions
diff --git a/src/conf_mode/nat.py b/src/conf_mode/nat.py
index a938021ba..564438237 100755
--- a/src/conf_mode/nat.py
+++ b/src/conf_mode/nat.py
@@ -23,7 +23,6 @@ from vyos.base import Warning
 from vyos.config import Config
 from vyos.configdep import set_dependents, call_dependents
 from vyos.template import render
-from vyos.template import is_ip_network
 from vyos.utils.kernel import check_kmod
 from vyos.utils.dict import dict_search
 from vyos.utils.dict import dict_search_args
diff --git a/src/helpers/teardown-config-session.py b/src/helpers/teardown-config-session.py
index c94876924..8d13e34cb 100755
--- a/src/helpers/teardown-config-session.py
+++ b/src/helpers/teardown-config-session.py
@@ -13,11 +13,8 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-#
 
 import sys
-import os
 
 from vyos.vyconf_session import VyconfSession
 
diff --git a/src/op_mode/image_installer.py b/src/op_mode/image_installer.py
index 27371a18f..d1f670ae9 100755
--- a/src/op_mode/image_installer.py
+++ b/src/op_mode/image_installer.py
@@ -19,7 +19,7 @@
 
 from argparse import ArgumentParser, Namespace
 from pathlib import Path
-from shutil import copy, chown, rmtree, copytree
+from shutil import copy, chown, rmtree, copytree, disk_usage
 from glob import glob
 from sys import exit
 from os import environ
@@ -62,6 +62,7 @@ from vyos.version import get_version_data
 # define text messages
 MSG_ERR_NOT_LIVE: str = 'The system is already installed. Please use "add system image" instead.'
 MSG_ERR_LIVE: str = 'The system is in live-boot mode. Please use "install image" instead.'
+MSG_ERR_NOT_ENOUGH_SPACE: str = 'Image upgrade requires at least 2GB of free drive space.'
 MSG_ERR_NO_DISK: str = 'No suitable disk was found. There must be at least one disk of 2GB or greater size.'
 MSG_ERR_IMPROPER_IMAGE: str = 'Missing sha256sum.txt.\nEither this image is corrupted, or of era 1.2.x (md5sum) and would downgrade image tools;\ndisallowed in either case.'
 MSG_ERR_INCOMPATIBLE_IMAGE: str = 'Image compatibility check failed, aborting installation.'
@@ -976,6 +977,14 @@ def add_image(image_path: str, vrf: str = None, username: str = '',
     if image.is_live_boot():
         exit(MSG_ERR_LIVE)
 
+    # Trying to upgrade with insufficient space can break the system.
+    # It's better to be on the safe side:
+    # our images are a bit below 1G,
+    # so one gigabyte to download the image plus one more to install it
+    # sounds like a sensible estimate.
+    if disk_usage('/').free < (2 * 1024**3):
+        exit(MSG_ERR_NOT_ENOUGH_SPACE)
+
     environ['REMOTE_USERNAME'] = username
     environ['REMOTE_PASSWORD'] = password