default hostname now is `fedora`, used to be `localhost`

[vrutkovs]

Booted 33.20201006.1.0 from next stream on GCP and default hostname is fedora:

[    2.041577] systemd[1]: No hostname configured.
[    2.042356] systemd[1]: Set hostname to <fedora>.

OKD-on-FCOS expects default hostname to be localhost (as on AWS).

See openshift/machine-config-operator#2160 (comment)

[bdurrow]

perhaps related? https://github.com/peckato1/fedora-systemd-package/commit/6eb8bcde288dda39b163e87ee0926f6f30fcad73

[bdurrow]

This is what I see in my boot logs:

Welcome to �[0;38;2;60;110;180mFedora CoreOS 33.20201006.10.2 dracut-050-63.git20200529.fc33 (Initramfs)�[0m!

[    2.456683] systemd[1]: No hostname configured.
[    2.457970] systemd[1]: Set hostname to <fedora>.

According to the systemd code this indicates that systemd was compiled with FALLBACK_HOSTNAME set to fedora perhaps with -Dfallback-hostname=fedora
https://github.com/systemd-rhel/rhel-8/blob/45d093a37b6f8c2ceae9bfd090c5265f35413b46/src/core/hostname-setup.c#L42

Prior to pivot the console log shows:

Welcome to �[0;34mFedora CoreOS 32.20200923.3.0 dracut-050-61.git20200529.fc32 (Initramfs)�[0m!

[    2.417343] systemd[1]: No hostname configured.
[    2.418432] systemd[1]: Set hostname to <localhost>.

So it appears that this is baked into the image that pivot “pivots” to in this case:

[    0.000000] Command line: BOOT_IMAGE=(hd0,gpt1)/ostree/fedora-coreos-a370d0067f2cb442383e4725688a2bfb92a84f59ceb6cd9ead44826dcc53634a/vmlinuz-5.8.13-300.fc33.x86_64 systemd.unified_cgroup_hierarchy=0 console=tty0 console=ttyS0,115200n8 ostree=/ostree/boot.0/fedora-coreos/a370d0067f2cb442383e4725688a2bfb92a84f59ceb6cd9ead44826dcc53634a/0 ignition.platform.id=gcp root=UUID=b583abc4-1973-439f-8aa2-169f7f218dc2 rw rootflags=prjquota

[vrutkovs]

Ways to fix it:

• Update systemd-resolved to use localhost - might take time to propagate in the next stream, as it would be Fedora-wide update. It probably would be pushed back, as its important for GCP install of OKD
• Update it in FCOS. Again, not sure its worth it
• Update afterburn to replace fedora hostname with localhost

I'm not entirely sure which platforms are affected - so far AWS is known to work and it certainly breaks on GCP. Could we give a try on all FCOS-supported platforms?

Seems afterburn fix is the easiest to implement, but not sure if its a good idea to clean up after systemd-resolved

[jlebon]

Maybe let's keep discussing in openshift/machine-config-operator#2160 how to proceed before doing anything here?

[lucab]

I was a bit puzzled by this bug report, so I checked the behavior of a plain FCOS 33.x on GCP and I can see the hostname properly set from DHCP in initramfs:

NetworkManager[490]: <info>  [1603701253.4075] policy: set 'Wired Connection' (ens4) as default for IPv4 routing and DNS
NetworkManager[490]: <info>  [1603701253.4075] policy: set-hostname: set hostname to 'lbruno-temp.c.example.internal' (from DHCPv4)

This seems right to me, and it also matches the behavior I'd expect on other platforms.
How does OKD end up having fedora instead? Can we see the full initramfs logs to check what's going on?

[bdurrow]

Right, okd disables DHCP on GCP:
https://github.com/openshift/machine-config-operator/blob/f2489433faacc32a7ead1caafcf076b943ffc9d8/templates/common/gcp/files/etc-networkmanager-conf.d-hostname.yaml#L12

If it weren't for that I wouldn't personally have a problem with my deployments but I have modified my installer to allow me to set my clusterdomain to the basedomain instead of having to have a 4 segment domain name.

[lucab]

I've opened https://bugzilla.redhat.com/show_bug.cgi?id=1892235 for Fedora package owners to explore whether the branding sugar can be applied in a different place or in some other way which would be easier to control at provisioning time.