How to debug an ignition file

I am trying to install OCP 4.3 using PXE

I can boot coreos_production_pxe.vmlinuz and fedora-coreos-32.20200601.3.0-live-kernel-x86_64 (I cannot find an appropriate kernel/initrd for rhel coreos). When I PXE boot these systems, I have DNS, internet access, etc. so I’m pretty confident my infrastructure is okay.

When I try to run the coreos installer, it just hangs and then 5 minutes later the system resets. I see it download the ignition file and the root FS image.

Is there a way to get debugging info from ignition in real time?

one option

remove console=ttyS0 from the kernel command line and you can watch ignition do its thing


The likely problem however is that you are doing a mix-and-match between OCP 4.3 and Fedora CoreOS, which do use incompatible version of Ignition configuration. OCP is a product which is by design coupled to its own operating system (RHCOS), and Fedora CoreOS is not a drop-in a replacement for that.

sorry, that wasn’t clear. I am using the RHEL Core OS installer and initrd when I run the install. I only mention the others because I used them to prove to myself that this wasn’t a setup issue.

I now know the issue is unsupported hardware. When I boot the RHEL CoreOS kernel, my SSD does not show up as a drive. When I boot fedora/coreos, I can see it. So apparently RHEL CoreOS has a smaller supported hardware list. Unfortunately. I can’t see the supported HW list because I am a partner, not a customer.

RHEL CoreOS is RHEL, see for some notable drivers dropped from RHEL8 (some of those may still exist in Fedora, confusingly).

I see. Then the detour through Fedora CoreOS it likely not useful as the kernel and driver plumbing is quite different (even just for the kernel versions).

My understanding is that you may have access to vanilla RHEL images and docs. If so, please try spinning up a RHEL 8.x on that same hardware and see how it goes. As RHCOS is the same OS content as RHEL but assembled in a way to suit OpenShift better, the same list of supported hardware should apply.

As a last step if you see major differences on your hardware between RHEL 8 and RHCOS, feel free to report that on Bugzilla against Openshift/RHCOS.

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Bummer, I was hoping to learn how to debug an ignition file.

the only advice I have there is remove “console=ttyS0” from the kernel command line and watch the boot process

I booted RHEL 8.2 and it also does not see my SSDs. I am going to investigate if this is an issue with the controller or the SSD itself by booting fedora or ubuntu and checking the components against