/docs/latest/installing/customizing-the-image/ Recent content in Customizing the image on Flatcar Container Linux Hugo en-us Copyright © The Flatcar Project Contributors. Copyright © Flatcar a Series of LF Projects, LLC. For website terms of use, trademark policy and other project policies please see <a href="https://lfprojects.org/policies/">lfprojects.org/policies</a>. /docs/latest/installing/customizing-the-image/customize-the-image/ Mon, 01 Jan 0001 00:00:00 +0000 /docs/latest/installing/customizing-the-image/customize-the-image/ <p>While <a href="/docs/latest/provisioning/ignition/">Ignition</a> cloud instance userdata is the preferred way of customizing an installation, it can be limiting when the customization concerns the kernel boot arguments or when no cloud instance userdata mechanism is in place. The partition with the OS <code>/usr</code> filesystem can&rsquo;t be modified because it is signed and gets auto-updated. Other partitions like the boot partition, the OEM partition, or even the root partition are open for customization. The boot partition can hold an additional EFI boot loader, the OEM partition can hold a GRUB file for the kernel arguments and possibly a default and/or base Ignition configuration, the root partition can hold the OS configuration and additional binaries. <strong>Note:</strong> Important is that you never boot the image because the first-boot initialization would make all your instances identical, causing problems with the update server, skips the regeneration of SSH host keys, and prevents Ignition from running. In case you have to do so for running Packer and/or Ansible, see the last section for common problems.</p>