Creating Images

Important

Various commands that manipulate images execute as user root, thereby requiring that the commands internally use sudo and requiring that user root must have access to the workspace that contains the administrator's images. Typically the per-user workspace is ~/.scyldcw/workspace/. If that directory is not accessible to the command executing as root, then another accessible directory can be employed. You can identify that alternative path by adding a modimg.workspace setting to ~/.scyldcw/settings.ini.

The scyld-install script creates an initial image with the default name DefaultImage based on publicly available repositories that match the head node operating system. If these repositories are not accessible, the scyld-add-boot-config tool can be run later with locally accessible repositories as described in Creating Local Repositories without Internet. Once the DefaultImage is created, use scyld-modimg to modify it directly. A safer approach is to use scyld-imgctl to clone the DefaultImage to new name, and then use scyld-modimg to modify that cloned image, leaving the DefaultImage untouched. See Modifying Images for details. You can also recreate the DefaultImage. See Recreating the Default Image for details.

You can also create a new image from an ISO or network accessible package repository. When doing that, consider the source of the components (packages) for the new image. A distro ties together a list of repos (package repositories) and an optional release. The package_manager is determined during image creation, but can be overridden in the distro. The initial default distro matches the original head node's version, uses package_manager yum, and downloads packages from a one item repos list containing "Rocky_base":

[admin@virthead]$  scyld-clusterctl distros ls -L
Distros
  Rocky
    name: Rocky
    packaging: rpm
    release: 8
    repos
      Rocky_appstream
      Rocky_base

[admin@virthead]$ scyld-clusterctl repos ls -L
Repos
Rocky_appstream
  keys: []
  name: Rocky_appstream
  urls
    http://dl.rockylinux.org/pub/rocky/$releasever/AppStream/$basearch/os/

Rocky_base
  keys: []
  name: Rocky_base
  urls
    http://dl.rockylinux.org/pub/rocky/$releasever/BaseOS/$basearch/os/

Use the following command to create a new image named "NewImg" using the default distro that downloads packages from the latest Rocky yum repo:

scyld-modimg --create --set-name NewImg

To create a Rocky image that contains something other than the latest Rocky release, see Creating Arbitrary Rocky Images. To create a RHEL image, see Creating Arbitrary RHEL Images.