fix(cloud-hypervisor): Add initrd for urunit configuration

[cmainas]

Description

Include cloud-hypervisor in Linux's MonitorCli in order to set the urunit configuration as the initrd for the cloud-hypervisor VM.

Related issues

• Fixes urunit config is not passed as initrd in cloud-hypervisor #842

How was this tested?

Executed the arbor.nbfc.io/nubificus/urunc/busybox-cloud-hypervisor-linux-raw:latest and checked urunit logs along with cloud-hypervisor command

logs:

[   11.863133] Run /urunit as init process
Warning: No configuration for block mounts
/bin/sh: can't access tty; job control turned off
/ # 
[   32.981715] ACPI: PM: Preparing to enter system sleep state S5
[   33.008017] reboot: Restarting system
[   33.020332] reboot: machine restart

urunit found the configuration since it reports no block configuration. Also the cloud-hypervisor command:

$ ps aux | grep cloud
root       11277  7.8  0.1  19348  7052 pts/1    S+   15:59   0:00 sudo docker run --rm -it --runtime io.containerd.urunc.v2 harbor.nbfc.io/nubificus/urunc/busybox-cloud-hypervisor-linux-raw:latest
root       11278  0.0  0.0  19348  2588 pts/3    Ss   15:59   0:00 sudo docker run --rm -it --runtime io.containerd.urunc.v2 harbor.nbfc.io/nubificus/urunc/busybox-cloud-hypervisor-linux-raw:latest
root       11279 15.7  0.7 1809316 29568 pts/3   Sl+  15:59   0:01 docker run --rm -it --runtime io.containerd.urunc.v2 harbor.nbfc.io/nubificus/urunc/busybox-cloud-hypervisor-linux-raw:latest
root       11319 52.4  0.9 287932 36608 ?        Ssl  15:59   0:03 /opt/urunc/bin/cloud-hypervisor --memory size=268M,shared=on --cpus boot=1 --kernel /cntrRootfs/.boot/kernel --console off --serial tty --seccomp true --net tap=tap0_urunc,mac=92:18:8b:9d:fa:a9,mtu=1500 --initramfs /urunit.conf --fs tag=fs0,socket=/tmp/vhostqemu --cmdline panic=-1 console=ttyS0 root=fs0 rw rootfstype=virtiofs ip=172.17.0.2::172.17.0.1:255.255.0.0:urunc:eth0:off retain_initrd URUNIT_CONFIG=/sys/firmware/initrd init=/urunit -- /bin/sh
cmainas    11371  0.0  0.0   9144  2260 pts/4    S+   15:59   0:00 grep --color=auto cloud

LLM usage

N/A

Checklist

• I have read the contribution guide.
• The linter passes locally (make lint).
• The e2e tests of at least one tool pass locally (make test_ctr, make test_nerdctl, make test_docker, make test_crictl).
• If LLMs were used: I have read the llm policy.

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[ananos]

Tested this on our dev box (CLH v50.0, virtiofsd 1.13.2). First reproduced #842 on main with the busybox-cloud-hypervisor-linux-raw image: the guest boots over virtiofs but urunit reports

Read configuration file: No such file or directory
Could not read file /sys/firmware/initrd

With this patch the same image boots and urunit finds its configuration ("Warning: No configuration for block mounts", which is the expected output for this image), and the CLH command line now carries --initramfs /urunit.conf. Also ran our standard qemu/fc boots with the patched binary -- no regression for the other monitors.

The fix itself is minimal and in the right place: BuildExecCmd for cloud-hypervisor already translated ExtraInitrd to --initramfs, it was only the MonitorCli gate that left CLH out. LGTM!

[ananos]

Verified on our dev box (details in the comment above) -- reproduced #842 on main and confirmed the fix. LGTM!