Fix growvols multipath partition_delimiter detect

On nodes with Fiber Channel multipath, the growvols command is
failing sometimes with the following stack trace:

Traceback (most recent call last):
  File "/usr/local/sbin/growvols", line 650, in <module>
    sys.exit(main(sys.argv))
  File "/usr/local/sbin/growvols", line 541, in main
    partnum = find_next_partnum(devices, disk)
  File "/usr/local/sbin/growvols", line 341, in find_next_partnum
    max_partnum = max(max_partnum, int(dev_name[disk_name_length:]))
ValueError: invalid literal for int() with base 10: 'p1'

The error is related to the kernel naming scheme for disk partitions.
If the disk name is ending with a digit, the kernel adds "pX" (where
X is  the partition number) instead of just "X" when the disk name
ends with a letter.

Consulting the manual page multipath.conf(5), the partition_delimiter
is configurable. If partition_delimiter is <unset> (the default) a
delimiter 'p' is inserted only if the map name ends in a digit. If
however the user configured a partition_delimiter, it will always be
used.

To try to handle both cases, use a regular expression to catch only
the digits at the end of the string.

Authored-By: mcr.opensource@gmail.com
Co-Authored-By: hjensas@redhat.com
Closes-Bug: #2109988
Change-Id: Ifbd58000601b7fc5635dcc2c7a897462000319b0

diskimage_builder/elements/growvols/static/usr/local/sbin/growvols

@@ -43,6 +43,9 @@ UNIT_BYTES_FORMAT = {
     'GiB': 1073741824
 }
 
+# Regular expression to get digits at the end of a string
+DIGITS_EOF_STR_RE = re.compile(r'\d+$')
+
 # Only create growth partition if there is at least 1GiB available
 MIN_DISK_SPACE_BYTES = UNIT_BYTES['GiB']
 
@@ -363,7 +366,15 @@ def find_next_partnum(devices, disk):
             if dev_name in seen_devs:
                 continue
             seen_devs.add(dev_name)
-            max_partnum = max(max_partnum, int(dev_name[disk_name_length:]))
+            # Multipath device names may have a partition_delimiter between
+            # the base device name and the partition number. By default, if
+            # partition_delimiter is unset in the multipath configuration and
+            # the base name ends in a digit, a 'p' is inserted.
+            # A regular expression is used to reliably extract trailing
+            # digits, regardless the presence of a partition delimiter or not.
+            max_partnum = max(max_partnum,
+                              int(DIGITS_EOF_STR_RE.search(
+                                  dev_name[disk_name_length:]).group(0)))
         return max_partnum + 1
 
 

diskimage_builder/elements/growvols/tests/test_growvols.py

@@ -11,6 +11,7 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
+import copy
 import importlib
 import os
 import sys
@@ -488,6 +489,19 @@ class TestGrowvols(base.BaseTestCase):
         disk = growvols.find_disk(opts, devices)
         self.assertEqual(6, growvols.find_next_partnum(devices, disk))
 
+    def test_find_next_partnum_multipath_partition_delimiter(self):
+        opts = mock.Mock()
+        opts.device = 'mpath2'
+        local_lsblk = copy.deepcopy(LSBLK_MULTIPATH)
+        local_lsblk = local_lsblk.replace('mpatha1', 'mpath2p1')
+        local_lsblk = local_lsblk.replace('mpatha2', 'mpath2p2')
+        local_lsblk = local_lsblk.replace('mpatha3', 'mpath2p3')
+        local_lsblk = local_lsblk.replace('mpatha4', 'mpath2p4')
+        local_lsblk = local_lsblk.replace('mpatha', 'mpath2')
+        devices = list(growvols.parse_shell_vars(local_lsblk))
+        disk = growvols.find_disk(opts, devices)
+        self.assertEqual(6, growvols.find_next_partnum(devices, disk))
+
     def test_find_next_device_name(self):
         devices = list(growvols.parse_shell_vars(LSBLK))
         disk = {

releasenotes/notes/fix-growvols-multipath-partition-delimiter-b93d07653b635a7c.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixed an issue in the growvols element where a ``partition_delimiter``
+    inserted between the device name and the partition number for multipath
+    devices was not handled correctly. This fix resolves `bug 2109988
+    <https://bugs.launchpad.net/diskimage-builder/+bug/2109988>`_.
+