Additional overlays to support provision-to-disk without ignition

- sfdisk - partitions the disk
- mkfs - formats partitions
- mkswap - formats partitions for swap
- systemd.mount - explicit creation of systemd mount units
- systemd.swap - explicit creation of systemd swap units

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

userdocs/nodes/disks.rst

@@ -4,7 +4,8 @@ Provisioning disks
 
 As a tech preview, Warewulf provides structures to define disks, partitions, and
 file systems. These structures can generate a configuration for `Ignition`_ to
-provision partitions and file systems dynamically on cluster nodes.
+provision partitions and file systems dynamically on cluster nodes, or with
+sfdisk, mkfs, and mkswap during boot.
 
 .. _Ignition: https://coreos.github.io/ignition/
 

userdocs/overlays/overlays.rst

@@ -371,6 +371,105 @@ specified with a ``localtime`` tag.
 
    wwctl profile set default --tagadd="localtime=UTC"
 
+sfdisk
+------
+
+The **sfdisk** overlay partitions block devices during wwinit. Configuration may
+be provided using native disk and partition configuration or via an ``sfdisk``
+resource.
+
+Multiple devices can be partitioned, with each device provided as an item in
+``sfdisk`` list.
+
+.. code-block:: yaml
+
+   sfdisk:
+     - device: /dev/sda
+       label: gpt
+       partitions:
+         - device: /dev/sda1
+           name: sfdisk-rootfs
+           size: 4194304
+         - device: /dev/sda2
+           name: sfdisk-scratch
+           size: 1048576
+         - device: /dev/sda3
+           name: sfdisk-swap
+           size: 2097152
+
+All headers and named partition fields supported by the ``sfdisk`` input format
+are supported in the ``sfdisk`` resource.
+
+If any disk/partition configuration is provided for a node with explicit
+arguments to ``wwctl <node|profile> set``, the ``sfdisk`` resource is ignored.
+
+To use the sfdisk overlay, include sfdisk in the Dracut image. Optionally also
+include blockdev and/or udevadm, to allow the partition table to be re-scanned.
+
+.. code-block:: shell
+
+   wwctl image exec rockylinux-8 -- /usr/bin/dracut --force --no-hostonly --add wwinit --install sfdisk --install blockdev --install udevadm --regenerate-all
+
+For more information, see the :ref:`provision to disk` section.
+
+mkfs
+----
+
+The **mkfs** overlay formats block devices during wwinit. Configuration may be
+provided using native filesystem fields or via an ``mkfs`` resource.
+
+.. code-block:: yaml
+
+   mkfs:
+     - device: /dev/sda1 # the device to format
+       type: xfs # what type of file system to create
+       options: -b 1024 # additional options to pass to mkfs
+       overwrite: false # whether to overwrite an existing format
+       size: 0 # defaults to the full device
+
+If any filesystem configuration is provided for a node with explicit arguments
+to ``wwctl <node|profile> set``, the ``mkfs`` resource is ignored.
+
+To use the mkfs overlay, include mkfs and any necessary file-system-specific
+sub-commands in the Dracut image. Optionally also include wipefs to detect
+existing file systems.
+
+.. code-block:: shell
+
+   wwctl image exec rockylinux-9 -- /usr/bin/dracut --force --no-hostonly --add wwinit --install mkfs --install mkfs.ext4 --install wipefs --regenerate-all
+
+For more information, see the :ref:`provision to disk` section.
+
+mkswap
+------
+
+The **mkswap** overlay formats block devices during wwinit. Configuration may be
+provided using native filesystem fields or via a ``mkswap`` resource.
+
+.. code-block:: yaml
+
+   mkswap:
+     - device: /dev/sda2 # the device to format
+       overwrite: false # whether to overwrite an existing format
+       label: swap # the label to set for the swap device
+
+If any filesystem configuration is provided for a node with explicit arguments
+to ``wwctl <node|profile> set``, the ``mkswap`` resource is ignored.
+
+To use the mkswap overlay, include mkswap in the Dracut image. Optionally also
+include wipefs to detect existing file systems.
+
+.. code-block:: shell
+
+   wwctl image exec rockylinux-9 -- /usr/bin/dracut --force --no-hostonly --add wwinit --install mkswap --regenerate-all
+
+systemd mounts
+--------------
+
+Two overlays, **systemd.mount** and **systemd.swap**, configure mounted and swap
+storage based on the configuration of native file system fields. They are often
+paired with the ``mkfs`` and ``mkswap`` overlays.
+
 host
 ----
 

userdocs/overlays/templates.rst

@@ -95,6 +95,16 @@ referenced symlink.
 
    {{ ImportLink "/etc/localtime" }}
 
+When paired with ``file``, ``ImportLink`` can create multiple symlinks from a
+single template.
+
+.. code-block::
+
+   {{ file "/tmp/test-link1"}}
+   {{ softlink "/tmp/test-target1" }}
+   {{ file "/tmp/test-link2"}}
+   {{ softlink "/tmp/test-target2" }}
+
 basename
 --------
 
@@ -133,6 +143,9 @@ Causes the processed template file to become a symlink to the referenced target.
   
    {{ printf "%s/%s" "/usr/share/zoneinfo" .Tags.localtime | softlink }}
 
+When paired with ``file``, ``softlink`` can create multiple symlinks from a
+single template.
+
 .. _readlink:
 
 readlink

userdocs/server/bootloaders.rst

@@ -454,6 +454,52 @@ Ignition must be included in the Dracut image.
 
 The necessary file system may alternatively be prepared out-of-band.
 
+With sfdisk and mkfs
+--------------------
+
+Systems that do not have access to Ignition (e.g., Rocky Linux 8) can provision
+the root file system using a combination of ``sfdisk`` and ``mkfs``. To use
+them, include ``sfdisk`` and ``mkfs`` in your system overlay. The ``sfdisk`` and
+``mkfs`` overlays provision disk and file systems during the first stage of a
+two-stage boot. This allows the root file system to be provisioned before the
+image is loaded.
+
+Configure the ``sfdisk`` and ``mkfs`` overlays using resources:
+
+.. code-block:: shell
+
+   wwctl node set wwnode1 \
+     --diskname /dev/vda --diskwipe \
+     --partname rootfs --partcreate --partnumber 1 \
+     --fsname rootfs --fsformat ext4 --fspath /
+
+In order to allow Dracut to provision the disk, partition, and file system, some
+additional commands must be included in the Dracut image, depending on which
+functionality is used:
+
+- **sfdisk:** writes the partition table
+
+  - **blockdev:** used to re-read the partition table after writing
+
+  - **udevadm:** used to trigger udev events after writing the partition table
+
+- **mkfs:** formats file systems (may also require file-system-specific commands like mkfs.ext4)
+
+  - **mkfs.ext4**, **mkfs.btrfs**, etc: used by mkfs to format specific file systems
+
+  - **wipefs:** used to determine if a file system already exists
+
+.. code-block:: shell
+
+   wwctl image exec rockylinux-8 -- /usr/bin/dracut --force --no-hostonly \
+     --add wwinit \
+     --install sfdisk \
+     --install blockdev \
+     --install udevadm \
+     --install mkfs \
+     --install mkfs.ext4 \
+     --install wipefs \
+     --regenerate-all
 
 Configuring the root device
 ---------------------------