Update cobbler signatures for RHEL8

Jul 3, 2019 · 3 min read

Cobbler is a great tool for PXE booting, I’ve been using it for years in both my personal and professional lives. Occassionally when a new OS comes out, you may find yourself needing to update cobbler’s distro signatures so it can import a new OS distribution. Thankfully, with their distro signatures being hosted on GitHub, this is really easy to do if your cobbler server isn’t able to pull the latest signatures on its own.

I know lots of us are booting OS’s these days from QCOW images in a cloud, but I still find PXE booting very useful. I’ve built up quite a few custom kickstart files over the years, including some that provision automatically with Ansible, so I still find myself building a quick kickstart file to automate a few of my server builds. Recently, I was building a RHEL8 host via PXE and realised I needed to update my cobbler server to include the new distro:

$ sudo mount rhel-8.0-x86_64-dvd.iso /mnt/
$ sudo cobbler import --name=RHEL-8.0 --arch=x86_64 --path=/mnt
task started: 2019-07-03_162132_import
task started (id=Media import, time=Wed Jul 3 16:21:32 2019)
No signature matched in /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64
!!! TASK FAILED !!!
$ sudo cobbler signature report
Currently loaded signatures:
debian:
	jessie
	squeeze
	stretch
	wheezy
...
redhat:
..
	fedora28
	fedora29
	rhel4
	rhel5
	rhel6
	rhel7
...
11 breeds with 82 total signatures loaded

Oh yea… no rhel8 listed… time to update. Cobbler provides a method to do this, but YMMV depending if the cobbler community has updated their github.io signature file. I did the update below, but noticed rhel8 still isn’t in this latest.json file:

$ sudo cobbler signature update
task started: 2019-07-03_162517_sigupdate
task started (id=Updating Signatures, time=Wed Jul 3 16:25:17 2019)
Successfully got file from https://cobbler.github.io/signatures/2.8.x/latest.json
*** TASK COMPLETE ***

Thankfully, there’s not a ton of magic to this signature file, and it’s available on the cobbler github project page. So I grabbed it directly, restarted cobbler, and I was able to see rhel8 included in the signature listing.

$ sudo wget https://raw.githubusercontent.com/cobbler/cobbler/master/config/cobbler/distro_signatures.json -O distro_signatures.json
--2019-07-03 16:25:48-- https://raw.githubusercontent.com/cobbler/cobbler/master/config/cobbler/distro_signatures.json
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.52.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.52.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 52085 (51K) [text/plain]
Saving to: ‘distro_signatures.json’

distro_signatures.json 100%[=========================================================================================================================================>] 50.86K --.-KB/s in 0.05s

2019-07-03 16:25:48 (978 KB/s) - ‘distro_signatures.json’ saved [52085/52085]

$ sudo systemctl restart cobblerd
$ sudo cobbler signature report
Currently loaded signatures:
debian:
	buster
	jessie
	squeeze
	stretch
	wheezy
...
redhat:
...
	fedora28
	fedora29
	fedora30
	ovz7
	rhel4
	rhel5
	rhel6
	rhel7
	rhel8
11 breeds with 95 total signatures loaded

Sweet. So I was able to import a RHEL8 ISO DVD into cobbler for use in my PXE booting.

$ sudo cobbler import --name=RHEL-8.0 --arch=x86_64 --path=/mnt
task started: 2019-07-03_162628_import
task started (id=Media import, time=Wed Jul 3 16:26:28 2019)
Found a candidate signature: breed=suse, version=sles15generic
Found a candidate signature: breed=redhat, version=rhel8
Found a matching signature: breed=redhat, version=rhel8
Adding distros from path /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64:
creating new distro: RHEL-8.0-x86_64
trying symlink: /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64 -> /export/www/cobbler/links/RHEL-8.0-x86_64
creating new profile: RHEL-8.0-x86_64
associating repos
checking for rsync repo(s)
checking for rhn repo(s)
checking for yum repo(s)
starting descent into /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64 for RHEL-8.0-x86_64
processing repo at : /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/AppStream
need to process repo/comps: /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/AppStream
looking for /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/AppStream/repodata/*comps*.xml
Keeping repodata as-is :/export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/AppStream/repodata
processing repo at : /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/BaseOS
need to process repo/comps: /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/BaseOS
looking for /export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/BaseOS/repodata/*comps*.xml
Keeping repodata as-is :/export/www/cobbler/ks_mirror/RHEL-8.0-x86_64/BaseOS/repodata
*** TASK COMPLETE ***

Happy PXE booting.