cmkinitramfs 0.1.0

A customizable simple initramfs generator

cmkinitramfs

A customizable initramfs generator made to support different kind of configurations.

cmkinitramfs

Build an initramfs from a configuration file.

First create the initramfs in a temporary directory. The initramfs is then installed to /usr/src/initramfs.cpio. The temporary directory used to build it is deleted. The kernel is cleaned from the initramfs related files (only relevant for built-in initramfs). Then the initramfs is copied and compressed to /boot/initramfs.cpio.xz.

Usage:

cmkinitramfs [--help] [--debug] [--dry-run] [--output OUTPUT] [kernel]

• --help: Show command usage.
• --dry-run: Only create the initramfs in a temporary directory, don't actually create the cpio archive or install it.
• --debug: Same as dry-run but also don't create files which requires root privileges (e.g. /dev/console), this allows the program to be run as a normal user.
• --output: Change the path of the created CPIO archive. Defaults to /usr/src/initramfs.cpio. If this is set, the initramfs will not be installed to /boot. Set to "-" to output the CPIO archive to stdout.
• --clean: Overwrite the temporary directory to build initramfs.
• --quiet: Don't output status informations to stderr.
• kernel: Selects a specific kernel version, defaults to the current kernel in /usr/src/linux. This option is used to cleanup the initramfs from the kernel tree and force it's update (only for built-in initramfs). Set to "none" to disable the cleanup.

This script run cmkinit, the path of the executable can be overriden with the CMKINIT_SCRIPT environment variable.

cmkinit

Build the /init script according to the configuration file. This program is used by cmkinitramfs, but can be called independently.

The content of the script is outputed to stdout.

cmkinitramfs.py

Module providing functions used by cmkinitramfs. This library should be the only code reading or writing to the temporary directory. All modification to the initramfs directory should pass through it.

This module provides a global variable DESTDIR to select the path of the initramfs temporary directory, it defaults to /tmp/initramfs.

The global variable QUIET is a boolean, if set to True, it will reduce the information outputed to stderr.

cmkinit.py

Module providing functions related to the construction of the /init script, and classes allowing the management of data sources used during the boot process.

Each data type in the configuration file has a corresponding Data class in this module.

cmkinitramfs.ini

This is the configuration file for both programs.

It contains one DEFAULT section and one section for each data source used during the init process.

It's default path is /etc/cmkinitramfs.ini and can be overriden by the CMKINITCFG environment variable.

DEFAULT section

This section configures the programs behaviour.

It defines the temporary directory used to build the initramfs, the root data source, the data sources required to boot, keyboard keymap, final init process to run, special files needed to be copied, ...

The /init script will first initialize itself, then load the root data source, then all the data sources enumerated in mountpoints.

Section of any type

Any section other than DEFAULT is a data source.

Configuration found for multiple types:

• type: Defines the type of data (e.g. luks, lvm, ...)
• need: Defines data sources needed for this data source to be loaded and used.
• load-need: Defines data sources needed for this data source to be loaded, but not needed to use it (load-time dependency). If a data source is only found in load-need, it will be unloaded when not needed anymore. For security purposes (e.g. LUKS key), load-time dependencies will load other data sources in order to be unloaded as soon as possible.
• source: Define a data source to use as source for the current one (e.g. a device to mount or unlock). Multiple formats are accepted:
  • "PATH=/path/to/file": Pass a file path as source (e.g. /root/key or /dev/sda1).
  • "UUID=xxxx-yyyy": Pass an UUID as source, this will use the findfs program to find a corresponding device.
  • "DATA=data-source-name": Pass an other data source as source, data sources know how to find their corresponding data. e.g. my-luks-partition will return /dev/mapper/my-luks-partition-name.
  • Anything else: Use it as a data source name, "xxx" is the same as "DATA=xxx".

Section type luks

Defines a LUKS data source.

Configuration (bold = mandatory):

• type
• need
• load-need
• source
• name: Name to use for the luks device.
• key: Defines a data source to use as LUKS key, same format as source.
• header: Defines a data source to use as LUKS header, same format as source.

Section type lvm

Defines a LVM logical volume.

Configuration (bold = mandatory):

• type
• need
• load-need
• vg-name: Defines the volume group name (e.g. my-vg).
• lv-name: Defines the logical volume name (e.g. my-lv).

Section type mount

Defines a mountpoint.

Configuration (bold = mandatory):

• type
• need
• load-need
• source
• mountpoint: Defines the mountpoint where to mount the source. Only directories directly within /mnt will be created if they don't exists, any other mountpoint has to have an existing directory. e.g. /mnt/a/b will fail if a or b does not exists, but /mnt/a will create a if it does not exists.
• filesystem: Defines the filesystem (e.g. ext4).
• options: Mount options to use, defaults to "ro". If you want to use system defaults, put "defaults" here and not an empty string.

Section type md

Defines a MD RAID device.

Configuration (bold = mandatory):

• type
• need
• load-need
• name: Name to use for the md device.
• source or sourceN: Defines data sources to use for assembling the raid device. Use source when only one source is needed. Use source0, source1, ... when one or more sources are needed. The indexing must start at 0.

Section type clone

Defines the cloning of a directory to another.

Configuration (bold = mandatory):

• type
• need
• load-need
• source
• destination: Specify the destination of the clone, same format as source.