vmtest 0.18.0

Helps run your tests in virtual machines
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114

#!/bin/bash
#
# This serves as the init process (PID 1) of the guest VM.
#
# Hopefully this stays fairly simple. The basic idea is that the host rootfs is
# shared as read-only (see `ro` kernel cmdline param).  Since everything
# appears as a regular directory (and not a mount point), we are allowed to
# "mount over" any directory to make it guest-specific and possibly writable.
#
# In general, we want to mount over most of the major pseudo-fs's like procfs,
# cgroup2, devtmpfs, etc.
#
# And for any directories we want the guest to to be able to write into, we can
# mount a tmpfs over it.

set -eu

export PATH={ path }

log() \{
    if [[ -e /dev/kmsg ]]; then
	echo "<6>vmtest: $*" >/dev/kmsg
    else
	echo "vmtest: $*"
    fi
}

# We start with the host procfs mounted in guest /proc.
#
# This may confuse some tools, so start off with mounting guest
# procfs at guest /proc.
/bin/mount -t proc -o nosuid,nodev,noexec proc /proc

# So the kernel doesn't panic when we exit
trap 'poweroff -f' EXIT

umask 022

# devtmpfs might be automounted through CONFIG_DEVTMPFS_MOUNT.
# Check if it's already mounted, and if not, mount it.
#
# Note we do the check in a kind of hacky way to keep the output
# silent. We cannot rely on redirecting output to /dev/null yet.
if ! mount | grep -q " /dev "; then
    log "devtmpfs not automounted, mounting at /dev"
    mkdir -p /dev
    mount -t devtmpfs -o nosuid,noexec dev /dev
fi

if [[ ! -d /dev/shm ]]; then
    log "Mounting tmpfs at /dev/shm"
    mkdir /dev/shm
    mount -t tmpfs -o nosuid,nodev tmpfs /dev/shm
fi

log "Mounting tmpfs at /run"
mount -t tmpfs -o nosuid,nodev tmpfs /run
ln -s /var/run ../run

log "Mounting sysfs at /sys"
mount -t sysfs -o nosuid,nodev,noexec sys /sys

log "Mounting debugfs at /sys/kernel/debug"
mount -t debugfs debugfs /sys/kernel/debug || log "Failed to mount debugfs. CONFIG_DEBUG_FS might be missing from the kernel config"

log "Mounting tracefs at /sys/kernel/debug/tracing"
mount -t tracefs tracefs /sys/kernel/debug/tracing || log "Failed to mount tracefs. CONFIG_DEBUG_FS might be missing from the kernel config"

log "Mounting cgroup2 at /sys/fs/cgroup"
mount -t cgroup2 -o nosuid,nodev,noexec cgroup2 /sys/fs/cgroup

log "Mounting tmpfs at /mnt"
mount -t tmpfs -o nosuid,nodev tmpfs /mnt

# Symlink /dev/fd to /proc/self/fd so process substitution works.
log "Symlink /dev/fd to /proc/self/fd"
[[ -a /dev/fd ]] || ln -s /proc/self/fd /dev/fd

log "Init done"

# Locate our QGA virtio port
vport=
for dir in /sys/class/virtio-ports/*; do
    if [[ "$(cat "$dir/name")" == "org.qemu.guest_agent.0" ]]; then
        vport_name=$(basename "$dir")
        vport="/dev/$\{vport_name}"
    fi
done
if [[ -z "$vport" ]]; then
    log "Failed to locate qemu-guest-agent virtio-port"
    exit 1
fi
log "Located qemu-guest-agent virtio port: $\{vport}"

# Send QGA logs out via kmsg if possible
qga_logs=
if [[ -e /dev/kmsg ]]; then
    qga_logs="--logfile /dev/kmsg"
fi

log "Spawning qemu-ga in the background"
# These --statedir and --pidfile match th default on typical QEMU builds, but
# versions exist where the default is something else. See
# https://github.com/danobi/vmtest/issues/101
qemu-ga --statedir /var/run --pidfile /var/run/qemu-ga.pid \
    --method=virtio-serial --path="$vport" $qga_logs -d


# Run a login shell
# In non-interactive mode, init will block on the shell process. The VM will be killed through QMP.
# In interactive mode, the user will be given a prompt, exiting the shell will trigger the trap function.
# We use `setsid` to make stdin a controlling tty and create a new session.
# https://stackoverflow.com/a/77840840
setsid --ctty --wait /bin/bash --login