How to customise machines

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MAAS allows machine customization before provisioning using Curtin or cloud-init.

Curtin pre-seeding

You can customize Curtin via the curtin_userdata template or by adding a custom file. Curtin supports early and late hooks for pre/post-installation customization.

  • Early Command Example:
    early_commands:
  signal: ["wget", "--no-proxy", "http://example.com/", "--post-data", "system_id=&signal=starting_install", "-O", "/dev/null"]
  • Late Commands Example:
    late_commands:
  add_repo: ["curtin", "in-target", "--", "add-apt-repository", "-y", "ppa:my/ppa"]
  custom: ["curtin", "in-target", "--", "sh", "-c", "/bin/echo -en 'Installed ' > /tmp/maas_system_id"]

Cloud-init pre-seeding

To customize cloud-init:

  • MAAS 3.4+ UI:
    Machines > machine > Actions > Deploy > Cloud-init user-data > enter customizations > Start deployment.

  • Other versions UI:
    Take action > Deploy > > Cloud-init user-data > enter customizations > Start deployment.

  • CLI:

    maas $PROFILE machine deploy $SYSTEM_ID user_data=<base-64-encoded-script>

Set default minimum kernel

To set the default kernel for all machines:

  • MAAS 3.4+ UI:
    Settings > Configuration > Commissioning > Default minimum kernel version > Save.

  • Other versions UI:
    Settings > General > Default minimum kernel version > Save.

  • CLI:

    maas $PROFILE maas set-config name=default_min_hwe_kernel value=$KERNEL

Set minimum kernel per machine

To set a minimum deployment kernel for a specific machine:

  • MAAS UI:
    Machines > machine > Configuration > Edit > Minimum kernel.

  • CLI:

    maas $PROFILE machine update $SYSTEM_ID min_hwe_kernel=$HWE_KERNEL

Set specific kernel during deployment

To set a kernel during deployment:

  • MAAS UI:
    Machines > machine > Take action > Deploy > choose kernel > Deploy machine.

  • CLI:

    maas $PROFILE machine deploy $SYSTEM_ID distro_series=$SERIES hwe_kernel=$KERNEL

Set global kernel boot options

To set global kernel boot options:

  • MAAS 3.4+ UI:
    Settings > Kernel parameters > enter options > Save.

  • Other versions UI:
    Settings > General > enter options > Save.

  • CLI:

    maas $PROFILE maas set-config name=kernel_opts value='$KERNEL_OPTIONS'

Kernel option tags

To create a tag with kernel options:

maas $PROFILE tags create name='$TAG_NAME' comment='$TAG_COMMENT' kernel_opts='$KERNEL_OPTIONS'

View tags:

maas admin tags read | jq -r '(["tag_name","tag_comment","kernel_options"] |(.,map(length*"-"))),(.[]|[.name,.comment,.kernel_opts]) | @tsv' | column -t

Enable hardware sync (MAAS 3.2+)

To enable hardware sync:

  • MAAS 3.4+ UI:
    Machines > machine > Actions > Deploy > Periodically sync hardware > Start deployment.

  • Other versions UI:
    Take action > Deploy > Periodically sync hardware > Start deployment.

  • CLI:

    maas $PROFILE machine deploy $SYSTEM_ID osystem=$OSYSTEM distro_series=$VERSION enable_hw_sync=true

View Hardware Sync Updates

View updates in the MAAS UI or CLI:

maas $PROFILE machine read $SYSTEM_ID

Configure Hardware Sync Interval

Configure the sync interval in MAAS settings.

Set default layout

To set the default storage layout for all machines:

  • MAAS UI:

    1. Settings > Storage > choose default layout.
    2. Enable Erase machines’ disks prior to releasing to force disk erasure.

  • CLI:

    maas $PROFILE maas set-config name=default_storage_layout value=$LAYOUT_TYPE

    Example for setting layout to flat:

    maas $PROFILE maas set-config name=default_storage_layout value=flat

Set per-machine layout

Set a storage layout for a ‘Ready’ machine:

maas $PROFILE machine set-storage-layout $SYSTEM_ID storage_layout=$LAYOUT_TYPE [$OPTIONS]

Example with LVM layout:

maas $PROFILE machine set-storage-layout $SYSTEM_ID storage_layout=lvm lv_size=5368709120

Erase disks

To erase a disk when releasing a machine:

  • Use machine release (singular) instead of machines release (plural).

Example:

maas $PROFILE machine release $SYSTEM_ID comment="some comment" erase=true [secure_erase=true || quick_erase=true]
  • Secure erasure uses the drive’s secure erase feature, if available.
  • Quick erasure wipes 2MB at the start and end of the disk. Not secure but faster.
  • If no options are specified, the disk will be overwritten with null bytes (slow).

Set conditional erasure

To perform secure erasure if available, or quick erasure otherwise:

maas $PROFILE machine release $SYSTEM_ID comment="some comment" erase=true secure_erase=true quick_erase=true
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Hi, there are a couple of issues with this paragraph:

  • Could more details be added about the curtin_userdata template? It mentions adding a custom file as described above, but there isn’t anything described above. Also, the path for this file is not specified, or how this works with snaps where you aren’t supposed to modify the files.

  • The link to “How images get deployed” has been moved. I guess it should be updated to point to https://maas.io/docs/about-images#heading--how-images-deploy ?

Thanks. :slight_smile:

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