curtin

Autoinstall crash when using tmpfs mounts : mount entry without 'device' missing: ['fstype']

Bug #2041725 reported by Florian Bobin on 2023-10-28

This bug affects 4 people

Affects		Status	Importance	Assigned to	Milestone
	curtin	New	Undecided	Unassigned

Bug Description

Hello !

I use the auto-install feature to automatically install my homelab server based on Ubuntu 22.04.3 LTS. However, today the autoinstaller crashed when curtin tried to add a standalone "tmpfs" mount in the target installation fstab, here the stack trace :

start: cmd-install/stage-partitioning/builtin/cmd-block-meta: configuring mount: tmpfs-tmp-mount
An error occured handling 'tmpfs-tmp-mount': ValueError - mount entry without 'device' missing: ['fstype']. ({'path': '/tmp', 'options': 'mode=1777,strictatime,nosuid,nodev,size=50%,nr_inodes=1m', 'spec': 'tmpfs', 'id': 'tmpfs-tmp-mount', 'type': 'mount'})
finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: configuring mount: tmpfs-tmp-mount
TIMED BLOCK_META: 11.849
finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: curtin command block-meta
Traceback (most recent call last):
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/commands/main.py", line 202, in main
     ret = args.func(args)
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/log.py", line 97, in wrapper
     return log_time("TIMED %s: " % msg, func, *args, **kwargs)
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/log.py", line 79, in log_time
     return func(*args, **kwargs)
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/commands/block_meta.py", line 127, in block_meta
     return meta_custom(args)
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/commands/block_meta.py", line 2248, in meta_custom
     handler(command, storage_config_dict, context)
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/commands/block_meta.py", line 1468, in mount_handler
     mount_apply(mount_data(info, storage_config),
   File "/snap/subiquity/5270/lib/python3.10/site-packages/curtin/commands/block_meta.py", line 1251, in mount_data
     raise ValueError(
ValueError: mount entry without 'device' missing: ['fstype']. ({'path': '/tmp', 'options': 'mode=1777,strictatime,nosuid,nodev,size=50%,nr_inodes=1m', 'spec': 'tmpfs', 'id': 'tmpfs-tmp-mount', 'type': 'mount'})
mount entry without 'device' missing: ['fstype']. ({'path': '/tmp', 'options': 'mode=1777,strictatime,nosuid,nodev,size=50%,nr_inodes=1m', 'spec': 'tmpfs', 'id': 'tmpfs-tmp-mount', 'type': 'mount'})
curtin: Installation failed with exception: Unexpected error while running command.

This doesn't make sense since I specified the 'fstype' in my mount definition. This working well with other kind of volume having the 'device' directive.

#cloud-config
...omitted for brevity
storage:
  swap:
    size: 0 # Disable creation of swapfile
  config:
    ...omitted for brevity
    # Snap lib volume (path: /var/lib/snapd, size: 5G)
    - id: lvm-system-snaplib-vol
      type: lvm_partition
      volgroup: lvm-system-vg
      name: snap-lib
      size: 5GB
      preserve: false
    - id: lvm-system-snaplib-fs
      type: format
      volume: lvm-system-snaplib-vol
      fstype: ext4
      preserve: false
    - id: lvm-system-snaplib-mount
      type: mount
      device: lvm-system-snaplib-fs
      path: /var/lib/snapd
    ## tmpfs mounts
    # /tmp tmpfs mount (path: /tmp, size: 50% total memory)
    - id: tmpfs-tmp
      type: mount
      spec: tmpfs
      fstype: tmpfs
      path: /tmp
      options: 'mode=1777,strictatime,nosuid,nodev,size=50%,nr_inodes=1m'

I dig a bit and found that the 'fstype' directive was not kept for whatever reason in the final generated storage configuration, so that's why the installation is failing imo.

# cat /var/log/installer/curtin-install/subiquity-partitioning.conf
# Autogenerated by Subiquity: 2023-10-28 15:19:23.214035 UTC
install:
  error_tarfile: /var/log/installer/curtin-errors.tar
  log_file: /var/log/installer/curtin-install.log
  log_file_append: true
  resume_data: /tmp/tmpo7eqfsjb/resume-data.json
  save_install_config: false
  save_install_log: false
  target: /target
  unmount: disabled
storage:
  ...omitted for brevity
  - path: /tmp
    options: mode=1777,strictatime,nosuid,nodev,size=50%,nr_inodes=1m
    spec: tmpfs
    id: tmpfs-tmp-mount
    type: mount

Then, I tried to search a bit in the curtin codebase but can't find anything useful to debug this issue. This was working fine previously when using the Ubuntu 22.04.2 ISO installer. Finally, I tried to disable the autoinstall auto-update when starting the installer and the installation worked as expected !

Here are the software versions used in both cases :

Installer crashed:
  - Ubuntu 22.04.3 ISO
  - Curtin 22.1-125-g7c18bf6a2
  - Subiquity 23.10.1

Installer working fine:
  - Ubuntu 22.04.3 ISO
  - Curtin 22.1-43-g9e9f66e83
  - Subiquity 23.08.1

I attached the crash log, I can provide more debug logs if needed.

Kind regards,

Florian BOBIN

See original description