Use Ignition in custom images

[Randy Kleinman]

Excuse me if this is covered in the docs, but I didn't see it.

Is it possible to install Ignition independently into one of my own OS
images and use it?

[a***@coreos.com]

Yes, but it's pretty involved. Additionally, some operations (i.e.
reformating the root filesystem) don't really makes sense for all operating
systems.

Ignition needs to run from the initramfs, and only run on first boot. Our
dracut modules are in https://github.com/coreos/bootengine. If you're
looking to use something other than dracut, you're largely in uncharted
territory. They rely on a kernel command line parameter `coreos.first_boot`
being specified to indicate its the first boot and Ignition should run.
This is set by grub which looks for a file in /boot to indicate it's the
first boot. This is removed by the ignition-quench unit after Ignition runs.

Ignition also (usually) requires networking, so your initramfs needs to
support that as well.

Hopefully that's enough to get started. Let me know if you have any
specific questions.

Post by Randy Kleinman
Excuse me if this is covered in the docs, but I didn't see it.
Is it possible to install Ignition independently into one of my own OS
images and use it?

[Randy Kleinman]

Thanks Andrew. Yes, I am looking at SLES and CentOS images with systemd so
I think ignition is a good fit. I just wasn't able to see any docs for this
specifically. Not seeing any tar.gz or RPM, is there a list of all of the
content that I would need to get started, or is it all in
https://github.com/coreos/bootengine?

-Randy


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Post by a***@coreos.com
Yes, but it's pretty involved. Additionally, some operations (i.e.
reformating the root filesystem) don't really makes sense for all operating
systems.
Ignition needs to run from the initramfs, and only run on first boot. Our
dracut modules are in https://github.com/coreos/bootengine. If you're
looking to use something other than dracut, you're largely in uncharted
territory. They rely on a kernel command line parameter `coreos.first_boot`
being specified to indicate its the first boot and Ignition should run.
This is set by grub which looks for a file in /boot to indicate it's the
first boot. This is removed by the ignition-quench unit after Ignition runs.
Ignition also (usually) requires networking, so your initramfs needs to
support that as well.
Hopefully that's enough to get started. Let me know if you have any
specific questions.

Post by Randy Kleinman
Excuse me if this is covered in the docs, but I didn't see it.
Is it possible to install Ignition independently into one of my own OS
images and use it?

[Stephen Lowrie]

Randy,

There are Ignition RPMs for CentOS 7 in EPEL Testing x86_64:
https://centos.pkgs.org/7/epel-testing-x86_64/ignition-0.26.0-0.2.git7610725.el7.x86_64.rpm.html
https://centos.pkgs.org/7/epel-testing-x86_64/ignition-dracut-0.26.0-0.2.git7610725.el7.noarch.rpm.html

But notably there are some features in there that need work (I believe
Ignition disks is entirely disabled among other things).

--Stephen

Post by Randy Kleinman
Thanks Andrew. Yes, I am looking at SLES and CentOS images with systemd so
I think ignition is a good fit. I just wasn't able to see any docs for this
specifically. Not seeing any tar.gz or RPM, is there a list of all of the
content that I would need to get started, or is it all in
https://github.com/coreos/bootengine?
-Randy
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Post by a***@coreos.com
Yes, but it's pretty involved. Additionally, some operations (i.e.
reformating the root filesystem) don't really makes sense for all operating
systems.
Ignition needs to run from the initramfs, and only run on first boot. Our
dracut modules are in https://github.com/coreos/bootengine. If you're
looking to use something other than dracut, you're largely in uncharted
territory. They rely on a kernel command line parameter `coreos.first_boot`
being specified to indicate its the first boot and Ignition should run.
This is set by grub which looks for a file in /boot to indicate it's the
first boot. This is removed by the ignition-quench unit after Ignition runs.
Ignition also (usually) requires networking, so your initramfs needs to
support that as well.
Hopefully that's enough to get started. Let me know if you have any
specific questions.

Post by Randy Kleinman
Excuse me if this is covered in the docs, but I didn't see it.
Is it possible to install Ignition independently into one of my own OS
images and use it?