Runit tools in busybox - up to the task?
Let's test busybox's runit applets in a hypothetical ;) scenario
when someone needs to stop running, say, systemd on, say, a Fedora machine.
No doubt this will expose various shortcomings.
Started with the machine configured and running under systemd.
Machine has xfce4 desktop environment installed.
Created /var/service and copied busybox/examples/var_service/* there.
Renamed/copied getty_tty1 to getty_tty9/10/11/12 (these consoles are not used
by existing setup).
Deleted dhcpd_if, ftpd, httpd, inetd, nmeter, tftpd (hmm, this needs a way
to store inactive services somewhere in a separate directory).
Adjusted fw/run (need more configurable way to do it; lacks a way to specify
more than one "external" (firewalled) interface).
Renamed/copied dhcp_if, dhcp_if_pinger, ifplugd_if each to a pair
of services for eth0 and wlan0.
Renamed supplicant_if only for wlan0.
Renamed zcip_if only for eth0 (how exactly zeroconf supposed to coexist
on more than one iface? They would all have 169.254/16 subnet - ?!).
Created a user to save all logs under:
groupadd -f --system logger
useradd --system -g logger -d /tmp -s /bin/false logger
Created /var/service/start:
#!/bin/sh
dir=/var/service
export PATH=/sbin:/bin:/usr/sbin:/usr/bin
exec /dev/null 2>&1
umask 022
cd "$dir" || exit $?
exec env - PATH="$PATH" runsvdir -P "$dir"
Created /etc/systemd/system/var.service:
[Unit]
Description=/var/service support
[Service]
ExecStart=/var/service/start
Added symlink: /etc/systemd/system/multi-user.target.wants/var.service ->
-> /etc/systemd/system/var.service
Deinstalled NetworkManager.
Rebooted and tested that services from /var/service do start, and nicely
coexist with the rest of the system.
Tested network (DHCP, zeroconf) and local DNS caching to work.
Now we will pry off X startup from systemd.
Changed /etc/systemd/system/default.target symlink to point to
/lib/systemd/system/multi-user.target instead of a GUI link.
Reboot. Now the system should start with Linux text VT's.
Created /var/service/lightdm_tty8 service. For user's convenience,
it's activated by pressing Enter at a chosen tty.
This is the run file:
#!/bin/sh
tty="/dev/${PWD##*/lightdm_}"
need "$tty"
exec <"$tty"
exec >"$tty" 2>&1
# If udevd is not up, X may fail to find any input devices. Wait for it.
need /run/udevd_ready
echo "Press Enter to start lightdm"; read junk
echo "* Starting lightdm[$$]"
exec \
env - PATH="$PATH" \
lightdm
Hmm. A tool to wait for a file is needed. So far this should do - /bin/need:
#!/bin/sh
i=0
while ! test -e "$1"; do
sleep "0.$i"
test "$i" = 9 || i=$((i+1))
done
Started it. Confirmed that GUI environment starts and seems to work just fine.
The big one: make system boot without systemd. Final preparations are:
* Create dbus and udevd services, start them only if systemd is not detected.
* Create init scripts. The word "init" here has more than one meaning...
Created /var/service/dbus-daemon service. run file:
#!/bin/sh
#exec >/dev/null
exec 2>&1
exec /dev/null
exec 2>&1
exec /run/udevd_ready
echo "Done: trigger+settle"
) &
echo "* Starting systemd-udevd[$$]"
exec \
env - PATH="$PATH" \
/usr/lib/systemd/systemd-udevd
It should auto-shutdown now, since systemd is detected.
Created /init script.
#!/bin/sh
export PATH=/sbin:/bin:/usr/sbin:/usr/bin
/etc/runit/1
exec 0>&- 1>&- 2>&-
# In this form, shell won't have an open fd to the script file
exec env - sh -c 'while :; do sleep 9999; done'
Isn't it a cutie.
In the spirit of runit tool, let's run system startup scripts from
/etc/runit/1. Create it:
#!/bin/sh
dir_and_not_mounted() {
test -d "$1" || return 1
! mountpoint -q -- "$1"
}
if fsck -A; then
true
else
echo "fsck exit code: $?. Boot will not continue."
while true; do sleep 9999; done
fi
mount -o remount,rw /
mount -a
dir_and_not_mounted /proc && mount -t proc proc /proc
dir_and_not_mounted /sys && mount -t sysfs sysfs /sys
# These are mounted by systemd, for some reason not via fstab. Mimic for now:
dir_and_not_mounted /tmp && mount -t tmpfs tmpfs /tmp
dir_and_not_mounted /run && mount -t tmpfs tmpfs /run
# Remove the mess left by systemd which possibly ran in initramfs:
for d in /sys/fs/cgroup/* /sys/fs/cgroup /sys/kernel/security; do
mountpoint -q -- "$d" && umount "$d"
done
# initramfs journald shit no one asked for:
test -d /run/log/journal && rm -rf /run/log/journal
#
# Start service supervision
/var/service/start &
Added "init=/init" to the kernel command line.
Reboot.
Enjoy new view in "ps -AH".
Reboot/poweroff does not need cooperation with init.
Copied examples/shutdown-1.0 to /app/shutdown-1.0.
Installed /sbin/* symlinks as described in README.
What's missing or needs improvement?
/var/service/syslog, /var/service/klogd.
"need" (waiting for a file/device/directory/socket to appear) needs to be
a real tool, not a shell loop. Maybe with an optional timeout?
Maybe it already exists?
ifplugd_handler needs a better way to code for the "if service FOO exists,
start it, if it does not, it's fine" idiom.
Admins would need a convenient tool to tail/page service logs just by name.
Something along the lines of
sview:
#!/bin/sh
test "$1" || {
echo "Syntax: ${0##*/} SERVICE"
exit 1
}
cd "/var/service/$1" || exit $?
test -x ./view && exec ./view
cd "log/logdir" || exit $?
h=`ttysize h`
exec tail -n $((h-1)) -F current 2>&1
svpage:
#!/bin/sh
test "$1" || {
echo "Syntax: ${0##*/} SERVICE"
exit 1
}
cd "/var/service/$1" || exit $?
test -x ./page && exec ./page
test "$PAGER" || PAGER=less
cd "log/logdir" || exit $?
cat @* current | $PAGER
"Perhaps I ought to explain," he continued. "You see, I'm a clockwork man." "Where did Mr. Winchape see him?" broke in Allingham, abruptly. The door closed behind them. Maitrank's fingers crooked and reached for Balmayne. The theorems, formul?, constants, tables, and rules, which are generally termed the principles of mechanics, are in a sense only symbols of principles; and it is possible, as many facts will prove, for a learner to master the theories and symbols of mechanical principles, and yet not be able to turn such knowledge [2] to practical account. That mad fury was also intensified considerably by the accusations about gruesome mutilations committed on German soldiers by Belgians, who were said to have cut off the noses, ears, genitals, and so on of their enemies. These rumours were so persistent that in the end it was generally believed in neutral countries that these things had happened frequently. (even toothaches) as interesting experiences, and be glad to know what "Well, I'm goin' to read your old letter for you, if you'll just gi' me time," remonstrated Maria. "What are you in such a hurry for, old cross-patch? Le' me see: Still, though his blood was already warming with the exhilarating thrill, there were some twinges of conscience. "Nothing. I'm fine." "The people of Rye now they all seem to say "What about Nature?" asked Richard, readjusting his pince-nez and thrusting forward his chin, whereby it was always known in court that he meant to "draw out" the witness. HoME苍井空拍的时候是真舒服吗
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