Example Dracut Dialog Module

The purpose of this respository is to demonstrate how to incorporate user input during a custom boot process facilitiated through a dracut built initrd. Why would someone do this? Here are some of the use-cases:

1. Finish a first time install: If you are familiar with the minimal Raspberry Pi installation, you will know what I mean. The created user for the minimal install is completed using a dialog at the tail of the initial boot.
2. Locked disk drives: In normal situations, a device can facilitate measured boot protection (encrypted system drives using an HSM). With a dialog perhaps there could be warning about what happened and what to do next.
3. Text base install wizards: A direct boot Linux image can facilitate a manual flashing using the dialog UI for some of the parameters.

Building This Example

The quickest way to test this module is to build the initrd image within a docker container (see this image), and direct boot from it using qemu.

The follow prerequisites:

1. Install docker for your platform.
2. apt-get install qemu qemu-system-x86

Once you have the completed the above, continue below:

1. Build the image: docker build -t dracut .
2. Jump into the image: docker run -it --rm --name dracut -v $PWD:/source:rw dracut
3. Build the image:

(cd source && cp -r 95dialogboot /usr/lib/dracut/modules.d/ && dracut -H boot-dialog.img)

4. Finally, direct boot using this ramd:

sudo qemu-system-x86_64 -kernel /boot/vmlinuz-$(uname -r) -initrd boot-dialog.img --append "rd.info"

You will see the example dialog on pre-mount. Pressing esc or ctl-c will continue the dracut execution.

What's next?

In almost all cases, the idea of halting the boot procedure for human interaction is a cause for concern. Enabling this behavior is something that is considered something of a "last resort", with an example being an oeprator is performing a human assisted flash of a device (ie: respberry pi). The boot should always be very fast and should not block! With that tenet in place, this repository will likely remain strictly an example to demonstrate that these exstenuating circumstances can be handled.