Re: Bug: machine id is never generated

[Gylstorff Quirin <quirin.gylstorff@siemens.com>]

On 7/21/22 17:41, Moessbauer, Felix (T CED SES-DE) wrote:
> Hi,
> 
> when booting plain ISAR images (with Debian11), the "/etc/machine-id" is never generated.
> This breaks a couple of services that depend on having the id.
> An example is the systemd-networkd with DHCP, leading to error messages like this one (and breaking networking):
> 
> systemd-networkd[277]: enp8s0: DHCP6 CLIENT: Failed to set identifier: No such file or directory
> 
> The error can manually be fixed by running "systemd-machine-id-setup", but this obviously does not work in embedded scenarios.
> 
> The root cause could be that /etc is read-only mounted when the first-boot-complete.target is reached.
> At least the logs indicate this:
> 
> journalctl --grep machine --no-pager
> -- Journal begins at Thu 2022-07-21 15:07:21 UTC, ends at Thu 2022-07-21 15:35:20 UTC. --
> Jul 21 15:07:21 test-image systemd[1]: System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.
> Jul 21 15:07:21 test-image systemd[1]: 1) /etc/machine-id exists and is populated.
> Jul 21 15:07:21 test-image systemd[1]: 2) /etc/machine-id exists and is empty.
> Jul 21 15:07:21 test-image systemd[1]: 3) /etc/machine-id is missing and /etc is writable.
> Jul 21 15:07:24 test-image systemd[1]: Condition check resulted in Commit a transient machine-id on disk being skipped.

/etc is read only after the initrd gives control to systemd. The remount 
from ro to rw of the rootfs occurs in systemd.


I tested it with my Debian machine and without /etc/machine-id to same 
behavior occurs.

 From my testing setting '/etc/machine-id' to "unitialized\n" results in 
the intended behavior with active first boot mechanic.


```
modified   meta/classes/image-postproc-extension.bbclass
@@ -57,7 +57,7 @@ ROOTFS_POSTPROCESS_COMMAND =+ 
"image_postprocess_machine_id"
  image_postprocess_machine_id() {
      # systemd(1) takes care of recreating the machine-id on first boot
      sudo rm -f '${IMAGE_ROOTFS}/var/lib/dbus/machine-id'
-    sudo rm -f '${IMAGE_ROOTFS}/etc/machine-id'
+    echo  "uninitialized\n"  | sudo tee '${IMAGE_ROOTFS}/etc/machine-id'
  }
```

This still needs to be tested with other images.

Quirin
> 
> Maybe Quirin knows more, as he implemented the postproc removal in 8b5e3f9.
> IIRC Jan also mentioned something that "rw" has to be added to the kernel cmdline, but this looks like a workaround as well.


> For the sake of completeness:
> 
> cat /proc/cmdline

> initrd=\initrd.img-5.10.0-16-amd64 LABEL=Boot root=PARTUUID=9ad286e9-8df8-42c2-ac7d-0f2d7387d03d rootwait console=tty0 console=ttyS0,115200
> 
> IMO this is a pretty critical bug as it affects a ton of images.
> 
> Best regards,
> Felix