红帽全球峰会7.4. Collecting the boot loader configuration information by using the bootloader RHEL system role
You can use the bootloader RHEL system role to gather information about the GRUB2 boot loader entries in an automated fashion. This way you can quickly identify that your systems are set up to boot correctly, all entries point to the right kernels and initial RAM disk images.
As a result, you can for example:
- Prevent boot failures.
- Revert to a known good state when troubleshooting.
- Be sure that security-related kernel command-line parameters are correctly configured.
Prerequisites
- You have prepared the control node and the managed nodes.
- You are logged in to the control node as a user who can run playbooks on the managed nodes.
-
The account you use to connect to the managed nodes has
sudopermissions for these nodes.
Procedure
Create a playbook file, for example,
~/playbook.yml, with the following content:--- - name: Configuration and management of GRUB2 boot loader hosts: managed-node-01.example.com tasks: - name: Gather information about the boot loader configuration ansible.builtin.include_role: name: redhat.rhel_system_roles.bootloader vars: bootloader_gather_facts: true - name: Display the collected boot loader configuration information debug: var: bootloader_factsFor details about all variables used in the playbook, see the
/usr/share/ansible/roles/rhel-system-roles.bootloader/README.mdfile on the control node.Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.ymlNote that this command only validates the syntax and does not protect against a wrong but valid configuration.
Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
After you run the preceding playbook on the control node, you will see a similar command-line output as in the following example:
... "bootloader_facts": [ { "args": "ro crashkernel=1G-4G:256M,4G-64G:320M,64G-:576M rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap $tuned_params quiet", "default": true, "id": "2c9ec787230141a9b087f774955795ab-6.12.el10_0.aarch64", "index": "1", "initrd": "/boot/initramfs-6.12.0.el10_0.aarch64.img $tuned_initrd", "kernel": "/boot/vmlinuz-6.12.0-0.el10_0.aarch64", "root": "/dev/mapper/rhel-root", "title": "Red Hat Enterprise Linux (6.12.0-0.el10_0.aarch64) 10" } ] ...The command-line output shows the following notable configuration information about the boot entry:
args- Command-line parameters passed to the kernel by the GRUB2 boot loader during the boot process. They configure various settings and behaviors of the kernel, initramfs, and other boot-time components.
id- Unique identifier assigned to each boot entry in a boot loader menu. It consists of machine ID and the kernel version.
root- The root filesystem for the kernel to mount and use as the primary filesystem during the boot.
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