5 Description of pre-built images #
SLE Micro can be deployed using pre-built images. Currently, there are two types of images available: raw disk images and selfinstall ISOs.
SLE Micro raw images are delivered for the AMD64/Intel 64 architecture, IBM Z ZSeries and also AArch64. The selfinstall images are currently delivered only for the AMD64/Intel 64 architecture. The pre-built images are intended to be configured on the first boot by using either Ignition or Combustion. The boot loader detects the first boot; for more information see Section 5.2, “First boot detection”. Each image has default mounted subvolumes as described in Section 5.1, “Default partitioning”. The procedure of deploying these images is described in Chapter 6, Deploying raw images.
Using firewall along with Podman may result in missing Podman-related firewall
rules after reloading the firewalld service. Therefore,
it is recommended to keep the firewall disabled if you intend to use Podman.
SLE Micro can run as a KVM host server—Xen is not supported. However, there are several limitations of SLE Micro running as a VM Host Server; for details refer to virtualization limits and support.
5.1 Default partitioning #
The pre-built images are delivered with a default partitioning scheme, which
can be changed during the first boot by using Ignition or Combustion. For a
procedure to repartition the system, refer to
Section 8.2, “config.ign” or
Section 9.2, “The script configuration file”.
If you intend to perform any changes to the default partitioning scheme, the root file system must be btrfs.
Each image has the following subvolumes:
/home /root /opt /srv /usr/local /var
The images also have mounted subvolumes for booting by default. The specific subvolumes differ according to the architecture.
The /etc directory is mounted as OverlayFS, where the
upper directory is mounted to /var/lib/overlay/1/etc/. For details, refer to Section 1.1, “/etc on a read-only file system”.
You can recognize the subvolumes mounted by default by the option
x-initrd.mount in /etc/fstab. Other
subvolumes or partitions must be configured either by Ignition or
Combustion.
5.2 First boot detection #
The configuration runs on the first boot only. To distinguish between the
first and subsequent boots, the flag file
/boot/writable/firstboot_happened is created
after the first boot took place. If the file is not present in the file
system, the attribute ignition.firstboot is passed to the
kernel command line, and thus both Ignition and Combustion are
triggered to run (in the initramfs).
After completing the first boot, the
/boot/writable/firstboot_happened flag file is created.
Even though the configuration may not be successful, due to improper or
missing configuration files, the
/boot/writable/firstboot_happened flag file is
created.
You may force the first boot configuration on subsequent boot by passing
the ignition.firstboot attribute to the kernel command
line or by deleting the
/boot/writable/firstboot_happened flag file.