rda0 / ansible-role-bootloader

Configures the bootloader including kernel boot parameters

bootloader

This role configures the bootloader (if present) including its kernel boot parameters. It does NOT install a bootloader, this is the job of the "os-installer".

The following bootloaders are supported and auto-detected:

• grub2: enabled when /etc/default/grub is present
• extlinux (syslinux): enabled when /syslinux.cfg is present

extlinux

If it detects extlinux, it will check if grub2 is installed alongside and show a warning.

This bootloader has two optional parameters (default = False):

• bootloader_extlinux_remove_grub: Remove grub
• bootloader_extlinux_install_to_bootsector: Install extlinux to the bootsector of /

custom host/group based inventory parameters

For example to add custom boot parameters and a serial console speed of 57600:

bootloader_serial_console_speed: '57600'
bootloader_kernel_parameters_custom:
  - 'foo=bar'
  - 'baz=raboof'

boot parameters from other roles

All roles that require the setting of special kernel boot parameters need to depend on this role and supply a list of parameters to this role via the dependencies vars attribute. This role (bootloader) needs to be enhanced to include this list of parameters. For an example of such a role, please refer to the role hypervisor and the variable bootloader_kernel_parameters_hugepages in role bootloader.

inventory config

The variable defaults in defaults/main.yml are tailor made for the production inventory, which has the serial console enabled by default, no grub password and a 5 second grub timeout.

For the workstations inventory, these variables are overidden in group_vars/all/bootloader.yml. The grub prompt is hidden (to show grub, press SHIFT during boot) and password protected.

The scheduler parameter elevator=noop is intentionally not included in the default configuration. It should only be included when it makes sense (Areca Controller and Kernel <= 4.19). It is therefore set via host_vars. I think in the future, we should aim for configuring the io scheduler via udev rules, because the newer multiqueue schedulers mq_*, cannot anymore be configured via kernel parameters. For an example see inventories/production/host_vars/phd-hv04/base.yml where the io scheduler must be set due to Areca Controller sending the wrong disk information to the Kernel.

The special kernel parameter for grub lvmwait=/dev/vg0/root is not included by default. This parameter should not be required for future installations. It can only have an effect, if the disk where the grub.cfg is located, is on an lvm volume. This parameter was required for some old Kernels.

All KVM virtual machines (except some exceptions) are using the extlinux bootloader, which is already configured in the defaults.