The Node Images and Boot Configurations section discusses the creation and modification of compute node images and how to add locally installed nodes to the system. ClusterWare provides support for an additional method of dynamically provisioning compute nodes: Kickstart.
Create Local Repo¶
ISO images of the installation DVDs for RHEL-family (see Supported Distributions and Features)
systems can be downloaded from their respective websites and imported into
ClusterWare as repos using the
scyld-clusterctl repos command.
scyld-clusterctl repos create name=Rocky8repo iso=@Rocky-8.7-x86_64-dvd1.iso
Once the upload completes, the ISO will be automatically forwarded to all head nodes and will be locally mounted on each. Below are the repository details immediately after the upload completes:
[cwadmin@virthead]$ scyld-clusterctl repos -i Rocky8repo ls -l Repos Rocky8repo iso chksum: e47d5ca236a3152d63814b32081a1a3261dd1cf4 filename: 4aceb9db1aef4670be82bf49855b514a mtime: 2023-01-31 23:07:36 UTC (0:08:31 ago) size: 11.3 GiB (12129927168 bytes) isolabel: Rocky-8-7-x86_64-dvd keys:  name: Rocky8repo urls <BASE_URL>/isomount/Rocky8repo/BaseOS/ <BASE_URL>/isomount/Rocky8repo/AppStream/
display URLs for the repositories identified on the ISO.
For example, there is a repository in the root of the uploaded Rocky-8 ISO,
<BASE_URL> tag is used as a placeholder to signify that any head
node can provide access.
When using such a URL,
<BASE_URL> with the actual head node's base URL,
The ISO can also be downloaded using the
scyld-clusterctl repos -i Rocky8repo download iso
Just like URL defined repos, repos created using ISOs can be referenced in distros. See Creating PXEboot Images in Node Images and Boot Configurations in this guide for details about using repos and distros to create compute node images.
Create Boot Configuration¶
In addition to providing content for distros, repos based on RHEL-family ISO images can also be used to kickstart locally installed compute nodes. To prepare a kickstart configuration, create a boot configuration that references the repo directly:
scyld-bootctl create name=Rocky8boot repo=Rocky8repo
The resulting boot configuration will automatically locate the kernel and initramfs on the ISO and default to using no image:
[cwadmin@virthead]$ scyld-bootctl -i Rocky8boot ls -l Boot Configurations Rocky8boot image: none initramfs: repo:images/pxeboot/initrd.img kernel: repo:images/pxeboot/vmlinuz last_modified: 2023-01-31 23:27:08 UTC (0:00:13 ago) name: Rocky8boot release: 4.18.0-425.3.1.el8.x86_64 repo: Rocky8repo
Initially this boot configuration can be used to boot a disked node with the live boot style assigned either by the boot configuration boot_style field or a _boot_style node attribute. When live booting a node, the cluster administrator will need to access the node's console to proceed through the operating system installation steps. To use the serial-over-lan BMC feature, the administrator may need to provide an appropriate console= cmdline, e.g.:
scyld-bootctl -i Rocky8boot update cmdline=console=ttyS0,115200
The specific details of the console and other command line arguments depend on the target hardware and are beyond the scope of this document. Once the installation process is complete, the compute node should use a next boot style in order to skip the PXE boot process and instead boot from the next boot device. Cluster administrators are encouraged to configure the BIOS of locally installed compute nodes to attempt PXE boot first and then boot from the local disk so that the next boot style works as intended.
A kickstart file configures how a kickstarted node is initialized at boot time.
The files are stored on the head node in the
In a multihead configuration this folder must currently be manually synced
between head nodes.
These kickstart files typically contain a limited set of
variables that will be substituted at download time.
For example, the ClusterWare package includes the
basic.ks kickstart file
that begins with the following contents:
# Node fields, attributes, status, and hardware are available in # dictionaries referenced by name or initial. Some examples: # # <node[ip]> # <a[_boot_config]> # <hardware[mac]> # Perform a SOL friendly text-based install. text # Pull some basics from the head node. url --url <root_url()> lang <head[lang]> keyboard <head[keymap]> timezone <head[timezone]>
Two different types of tags are supported, and both provide simple
text substitution. The first, exemplified by the
<repo_url()> tag, is a function call
that accepts as an optional argument the name of a ClusterWare repo. That tag
will be replaced by an appropriate URL for the named repo. Similarly,
certain values are represented as more of a dictionary-like reference,
<head[timezone]>. These tags provide a simple variable lookup
for information such as the head node timezone. The snippet above
shows all the currently supported tags except for the
<include(partial.ks)> tag. The
include tag allows a cluster
administrator to break the kickstart files into manageable hunks that
can then be included into a top-level kickstart file, much like a C or
C++ "#include <filename>".
basic.ks performs a boot time install of both the base
distribution core packages (e.g., from Rocky8repo) and the associated
ClusterWare clusterware-node package which is appropriate for that
particular base distribution.
Associate the boot configuration with a kickstart file:
scyld-bootctl -i Rocky8boot update kickstart=basic.ks
and associate a compute node to boot this boot configuration:
scyld-nodectl -i n0 set _boot_config=Rocky8boot
Finally, reboot node n0 to initiate the kickstart, which will take a few minutes to complete.
Once the freshly installed node has booted, there will be a
/root/anaconda-ks.cfg file that can be used as a starting point for
creating a more generalized kickstart file. If the cluster
administrator would like to reinstall the node the exact same way, the
simplest thing to do is copy that
anaconda-ks.cfg file to the head
node's kickstart directory and assign it to be used in the boot
# Copy the compute node's /root/anaconda-ks.cfg to the head node, # and then copy to the head node's kickstart files folder. cp anaconda-ks.cfg /opt/scyld/clusterware/kickstarts # And update the boot configuration to use the file. scyld-bootctl -i Rocky8boot update kickstart=anaconda-ks.cfg
After that file is in place, any compute node booted from that boot
configuration without the next or live boot style will boot using
the kernel and initramfs from the ISO, and a URL to the kickstart file
will be added to the kernel command line. Keep in mind that once a
node starts the kickstart process, it is a good idea to change its
boot style to next so that it does not reboot at the end of the
install process and immediately reinstall. Configuring the kickstart
process to end with a
shutdown command (see your operating system
documentation) is the current best practice.
If a cluster administrator wants to use a different kernel and/or
initramfs for kickstarting instead of the ones found on the ISO, those
can be replaced just like in any other boot configuration through the
update action. Updating them with an empty string will reset them
back to the detected paths:
scyld-bootctl -i Rocky8boot update kernel= initramfs=