Kernel arguments and environment variables can be set with WORKDIR when using krun

[eriksjolund]

Kernel arguments and environment variables can be set with WORKDIR when using krun

Preparation

1. Log in as root on a Fedora 41 system
2. Create file /root/test.bash containing

   #!/bin/bash
   set -o errexit
   set -o nounset
   argument=$1
   command=$2
   dir=$(mktemp -d)
   
   cat << EOF > $dir/Containerfile
   FROM docker.io/library/fedora
   RUN mkdir "/etc/ $argument"
   WORKDIR "/etc/ $argument"
   EOF
   
   podman build -q -t mytest $dir > /dev/null
   podman --runtime krun run --rm -t localhost/mytest $command
   

Example 1

Set kernel argument loglevel=7

Run command

bash test.bash loglevel=7 true

The following output is printed

[    0.340584] loop: module loaded
[    0.340849] tun: Universal TUN/TAP device driver, 1.6
[    0.341277] device-mapper: ioctl: 4.48.0-ioctl (2023-03-01) initialised: [email protected]
[    0.341678] Initializing XFRM netlink socket
[    0.341800] NET: Registered PF_INET6 protocol family
[    0.342494] Segment Routing with IPv6
[    0.342584] In-situ OAM (IOAM) with IPv6
[    0.342665] NET: Registered PF_PACKET protocol family
[    0.343246] NET: Registered PF_VSOCK protocol family
[    0.345757] NET: Registered PF_TSI protocol family
[    0.346034] IPI shorthand broadcast: enabled
[    0.349106] registered taskstats version 1
[    0.355095] Btrfs loaded, zoned=no, fsverity=no
[    0.355753] Key type encrypted registered
[    0.355903] clk: Disabling unused clocks
[    0.356118] virtio-fs: tag <> not found
[    0.356728] VFS: Mounted root (virtiofs filesystem) on device 0:21.
[    0.356956] devtmpfs: mounted
[    0.359573] Freeing unused kernel image (initmem) memory: 1836K
[    0.359831] Write protecting the kernel read-only data: 18432k
[    0.361788] Freeing unused kernel image (rodata/data gap) memory: 1264K
[    0.361953] Run /init.krun as init process
[    0.370394] reboot: Failed to start orderly reboot: forcing the issue
[    0.371127] reboot: machine restart

Example 2

Set environment variable myvar

bash test.bash myvar=hello "printenv myvar"

The following output is printed

hello

About the system

krun was built from git commit e9a2766

# rpm -q libkrun podman
libkrun-1.10.1-2.fc41.x86_64
podman-5.4.0-1.fc41.x86_64

# podman run --rm localhost/crunbuilder rpm -q libkrun
libkrun-1.10.1-2.fc41.x86_64

[giuseppe]

@slp PTAL