[sonic_installer] dont fail package migration (sonic-net#1591)

- What I did
Do not fail when user is doing downgrade. Fix sonic-net#7518

- How I did it
Ignoring failures.

- How to verify it
On master image install 202012 image.

Signed-off-by: Stepan Blyschak <stepanb@nvidia.com>

sonic_installer/common.py

@@ -31,13 +31,13 @@ def run_command(command):
         sys.exit(proc.returncode)
 
 # Run bash command and return output, raise if it fails
-def run_command_or_raise(argv):
+def run_command_or_raise(argv, raise_exception=True):
     click.echo(click.style("Command: ", fg='cyan') + click.style(' '.join(argv), fg='green'))
 
     proc = subprocess.Popen(argv, text=True, stdout=subprocess.PIPE)
     out, _ = proc.communicate()
 
-    if proc.returncode != 0:
+    if proc.returncode != 0 and raise_exception:
         raise SonicRuntimeException("Failed to run command '{0}'".format(argv))
 
     return out.rstrip("\n")

sonic_installer/main.py

@@ -232,17 +232,17 @@ def mount_squash_fs(squashfs_path, mount_point):
     run_command_or_raise(["mount", "-t", "squashfs", squashfs_path, mount_point])
 
 
-def umount(mount_point, read_only=True, recursive=False, force=True, remove_dir=True):
+def umount(mount_point, read_only=True, recursive=False, force=True, remove_dir=True, raise_exception=True):
     flags = []
     if read_only:
         flags.append("-r")
     if force:
         flags.append("-f")
     if recursive:
         flags.append("-R")
-    run_command_or_raise(["umount", *flags, mount_point])
+    run_command_or_raise(["umount", *flags, mount_point], raise_exception=raise_exception)
     if remove_dir:
-        run_command_or_raise(["rm", "-rf", mount_point])
+        run_command_or_raise(["rm", "-rf", mount_point], raise_exception=raise_exception)
 
 
 def mount_overlay_fs(lowerdir, upperdir, workdir, mount_point):
@@ -350,14 +350,18 @@ def get_path(path):
             run_command_or_raise(["mount", "--bind",
                                 os.path.join(VAR_RUN_PATH, DOCKERD_SOCK),
                                 os.path.join(new_image_mount, "tmp", DOCKERD_SOCK)])
+            run_command_or_raise(["chroot", new_image_mount, "sh", "-c", "command -v {}".format(SONIC_PACKAGE_MANAGER)])
+        except SonicRuntimeException as err:
+            echo_and_log("Warning: SONiC Application Extension is not supported in this image: {}".format(err), LOG_ERR, fg="red")
+        else:
             run_command_or_raise(["chroot", new_image_mount, SONIC_PACKAGE_MANAGER, "migrate",
                                 os.path.join("/", tmp_dir, packages_file),
                                 "--dockerd-socket", os.path.join("/", tmp_dir, DOCKERD_SOCK),
                                 "-y"])
         finally:
-            run_command("chroot {} {} stop".format(new_image_mount, DOCKER_CTL_SCRIPT))
-            umount(new_image_mount, recursive=True, read_only=False, remove_dir=False)
-            umount(new_image_mount)
+            run_command_or_raise(["chroot", new_image_mount, DOCKER_CTL_SCRIPT, "stop"], raise_exception=False)
+            umount(new_image_mount, recursive=True, read_only=False, remove_dir=False, raise_exception=False)
+            umount(new_image_mount, raise_exception=False)
 
 
 # Main entrypoint