Hi there,
(Cc'd a lot of people, so that hopefully everybody relevant
is included.)
Andreas Henriksson recently pointed me to the fact that there
are several problems with the current init-d-script in Debian
(which I use in my own packages to handle the non-systemd
cases), and he most prominently mentioned the problem that
with init-d-script systemctl redirection via direct calls to
the init script doesn't work properly (in contrast to normal
init scripts, where it does).
What bothered me is that many people (including Andreas) have
started suggesting not to use init-d-script because of its
problems but to rather use the previous template. I think
this is the wrong approach, because I'm perfectly happy in
maintaining something like:
http://sources.debian.net/src/open-isns/0.96-5/debian/open-isns-server.isnsd.init/
http://sources.debian.net/src/open-isns/0.96-5/debian/open-isns-discoveryd.isnsdd.init/
in my packages, but I would hate to have to maintain all of
the boilerplate code.
For this reason I promised Andreas that I'd take a closer look
at those and see what I can do.
I think I have a solution to both issues - and my solution
does not require any change to any individual init script,
and best of all it doesn't even require changes to any
sysvinit-related package (we get to have our cake and eat
it too):
The systemd package could install a diversion of
/lib/init/init-d-script and install its own wrapper. The
wrapper could check for systemd being run and properly handle
the redirect-to-systemctl case. On systems that have systemd
installed but are booted with something else the wrapper
would just source the original wrapper.
This has two distinct advantages:
- diversions now work properly for init-d-scripts
(fixes #826214)
- scripts that use init-d-script _and_ have a native systemd
service with the same name _and_ do _not_ implement custom
verbs in the init script (do_unknown) don't need to depend
on sysvinit-utils anymore. At the same time the entire
init-d-script logic does _not_ need to be installed on
such systems. (init-d-script packages without a native
services still need the dependency though, as expected.)
(fixes #826215)
I've developed a patch against current sid of the systemd
package and tested that on both systemd and sysvinit systems
extensively and made sure all of the code paths work.
The wrapper itself doesn't have much code, but I've added a
lot of comments to make sure that the corner cases (that are
all handled properly) are understood, so people modifying it
don't break it accidentally.
For the sysvinit people, to make it clear thst it doesn't
harmfully affect non-systemd systems: the basic structure of
the wrapper is the following:
#!/bin/sh
if [ -d /run/systemd/system ] ; then
# do systemd-specific stuff
fi
. /lib/init/init-d-script.sysv
exit $?
I have tested the following (with real live packages):
- systems booted with systemd, sysvinit-utils installed:
redirection works as expected, custom verbs are still
handled by init-d-script. The usage message is printed
by the original init-d-script.
- systems booted with systemd, sysvinit-utils not installed:
redirection works as expected, the usage message is
printed by the wrapper
- systems booted with sysvinit, systemd not installed:
everything still works
- systems booted with sysvinit, systemd installed: the
wrapper is a noop that just redirects to the original
init-d-script
- systems booted with sysvinit: installing a daemon,
calling the init script, installing systemd (the package),
calling the init script again, purging systemd, calling
the init script yet again
I've done these tests multiple times with various different
packages and made sure I was hitting every code path of the
added code.
I've attached a git am'able patch against systemd's
debian/232-8 tag in git. Feedback welcome.
Regards,
Christian
PS: There is one corner case that is still open when it comes
to init-d-script and systemd, which is technically neither of
these bugs, but I feel I should mention it: if no native
systemd service is provided in addition to the init-d-script
init script, then systemd still doesn't properly detect
whether reload is possible for that service. I don't think
this is a huge issue, because that can easily be worked
around by providing a native systemd service in addition to
the init script. One could detect this properly by adding
support to detect this to systemd's sysv-generator (or add an
additional new generator), but I don't think that is worth
the effort.
From 63b96c5399280c22f58eb69c8b5eb874d4a2b497 Mon Sep 17 00:00:00 2001
From: Christian Seiler <christ...@iwakd.de>
Date: Sun, 25 Dec 2016 10:36:51 +0100
Subject: [PATCH] Add wrapper for init-d-script
Divert the original /lib/init/init-d-script to init-d-script.sysv in
the same directory. An own wrapper is installed as
init-d-script.systemd. and a symlink to init-d-script is created after
the diversion is in place.
The wrapper has the following tasks:
1. Since init-d-script is surced after the init script name is
prepended to the parameter list (where the verb would usually be),
drop that again before sourcing the code that attempts the redirect
to systemctl.
This will make sure that the systemctl redirect works as expected.
If the logic doesn't redirect (custom verb, for example) the
argument list expected by the original init-d-script is restored
afterwards.
2. Since init-d-script can now be sourced on systemd systems, and will
redirect to systemd - any package that installs an init-d-script
based init script together with a systemd service with the same
name does not have to depend on sysvinit-utils anymore.
On systemd systems without the initscripts package, calling the
init script directly will result in systemctl being called by this
wrapper.
On non-systemd systems, the init system will depend on the
sysvinit-utils pacakge (via e.g. the initscripts package), which
then provide the original init-d-script, which will then be sourced
by the wrapper as a fallback.
However, if a custom verb is implemented in the init script
(i.e. the script defines a function do_unknowwn), the package
containing that init script must then still carry a dependency on the
sysvinit-utils package, because the original init-d-script must be
available.
The wrapper is installed with the systemd package, not the systemd-sysv
package, since once can boot into systemd (via init=) without having to
install the systemd-sysv package.
---
debian/extra/init-d-script.systemd | 89 ++++++++++++++++++++++++++++++++
debian/extra/init-functions.d/40-systemd | 11 ++--
debian/systemd.install | 1 +
debian/systemd.postinst | 12 +++++
debian/systemd.prerm | 10 ++++
5 files changed, 120 insertions(+), 3 deletions(-)
create mode 100755 debian/extra/init-d-script.systemd
diff --git a/debian/extra/init-d-script.systemd b/debian/extra/init-d-script.systemd
new file mode 100755
index 000000000..92232d02c
--- /dev/null
+++ b/debian/extra/init-d-script.systemd
@@ -0,0 +1,89 @@
+#!/bin/sh
+
+# Wrapper around sysv's init-d-script. This serves two purposes:
+#
+# 1. Since scripts using init-d-script prepend their own name to the
+# argument list before sourcing init-d-script, the logic to
+# redirect to systemctl in init-functions.d/40-systemd doesn't
+# properly detect the verb (start, stop, etc.) and will hence not
+# redirect to systemctl, but allow the init script to be run
+# directly. If systemd is running, this wrapper contains glue code
+# to make this work regardless.
+#
+# 2. init-d-script itself shouldn't need to be installed on pure
+# systemd systems if all installed packages provide native services
+# in addition to the init script they provide. In that case this
+# wrapper is sufficient to redirect to systemctl if an init script
+# is called directly regardless, without having to have the
+# init-d-script binary itself installed.
+#
+# The original init-d-script is diverted away to
+# /lib/init/init-d-script.sysv by systemd's postinst.
+
+if [ -d /run/systemd/system ] ; then
+ # Prevent recursion in badly written init scripts. (Same thing as
+ # init-d-script itself does.)
+ if [ x"${1#*init-d-script}" != x"${1}" ] ; then
+ exit 0
+ fi
+
+ INIT_D_SCRIPT_NAME="$1"
+ shift
+
+ if [ -f /lib/lsb/init-functions ] ; then
+ # Multiple sourcing of this is OK in case the redirect isn't
+ # performed, but in order for the redirect logic to work in the
+ # first place, this needs to happen with a restored argument
+ # list that contains the verb in first place.
+ . /lib/lsb/init-functions
+ else
+ # Not installed, but since only a redirect needs to be
+ # attempted in this case, it is possible to source the specific
+ # code directly. However, stubs for the functions used need to
+ # be defined first.
+ log_daemon_msg() { echo -n "$1:${2:+ $2}"; }
+ log_end_msg() {
+ case "$1" in
+ 0) echo . ;;
+ 255) echo " (warning)." ;;
+ *) echo " failed!" ;;
+ esac
+ }
+ . /lib/lsb/init-functions.d/40-systemd
+ fi
+
+ # This will not be reached in most cases, but just in case
+ # revert the shift (a custom verb called, for example).
+ set "$INIT_D_SCRIPT_NAME" "$@"
+ unset INIT_D_SCRIPT_NAME
+
+ if ! [ -f /lib/init/init-d-script.sysv ] ; then
+ # Invalid verb specified, so show usage here, since sysv's
+ # init-d-script is not installed. (If custom verbs are to be
+ # supported by the init script, the pacakge containing it needs
+ # to Depend on sysvinit-utils to make sure this case is never
+ # hit.)
+ _prog="${1##*/}"
+ if [ "$(systemctl -p CanReload --value show ${_prog%.sh}.service 2>/dev/null)" = "no" ] ; then
+ echo "Usage: $1 {start|stop|status|restart|try-restart|force-reload}" >&2
+ else
+ echo "Usage: $1 {start|stop|status|reload|restart|try-restart|force-reload}" >&2
+ fi
+ exit 3
+ fi
+fi
+
+# Redirect to the original implementation of init-d-script. This can
+# be reached in three cases:
+#
+# 1. systemd isn't running.
+# 2. A custom verb is implemented in the init script (do_unknown)
+# and the user called with that custom verb.
+# 3. reload was requested, but no native systemd service exists. In
+# that case, systemd's sysv-generator will not detect the service
+# as reloadable, and the current logic in
+# init-functions.d/40-systemd will not redirect to systemctl to
+# give the init script a chance to directly reload the service.
+
+. /lib/init/init-d-script.sysv
+exit $?
diff --git a/debian/extra/init-functions.d/40-systemd b/debian/extra/init-functions.d/40-systemd
index 8e31544b1..35198fb55 100644
--- a/debian/extra/init-functions.d/40-systemd
+++ b/debian/extra/init-functions.d/40-systemd
@@ -4,7 +4,12 @@
_use_systemctl=0
if [ -d /run/systemd/system ]; then
- prog=${0##*/}
+ if [ -n "$INIT_D_SCRIPT_NAME" ] ; then
+ script=${INIT_D_SCRIPT_NAME}
+ else
+ script=$0
+ fi
+ prog=${script##*/}
service="${prog%.sh}.service"
# Don't try to run masked services. systemctl <= 230 always succeeds here,
@@ -18,7 +23,7 @@ if [ -d /run/systemd/system ]; then
# Redirect SysV init scripts when executed by the user
if [ $PPID -ne 1 ] && [ -z "${init:-}" ] && [ -z "${_SYSTEMCTL_SKIP_REDIRECT:-}" ]; then
- case $(readlink -f "$0") in
+ case $(readlink -f "${script}") in
/etc/init.d/*)
_use_systemctl=1
# Some services can't reload through the .service file,
@@ -86,7 +91,7 @@ if [ "$_use_systemctl" = "1" ]; then
"x$1" = xforce-reload -o \
"x$1" = xstatus ] ; then
- systemctl_redirect $0 $1
+ systemctl_redirect $script $1
exit $?
fi
fi
diff --git a/debian/systemd.install b/debian/systemd.install
index 87cf0acbd..70a3354d0 100644
--- a/debian/systemd.install
+++ b/debian/systemd.install
@@ -65,3 +65,4 @@ var/lib
../../extra/dhclient-exit-hooks.d/ etc/dhcp/
../../extra/kernel-install.d/* usr/lib/kernel/install.d
../../extra/pam.d etc/
+../../extra/init-d-script.systemd /lib/init
diff --git a/debian/systemd.postinst b/debian/systemd.postinst
index 4701665d8..3aca12ccc 100644
--- a/debian/systemd.postinst
+++ b/debian/systemd.postinst
@@ -150,4 +150,16 @@ if dpkg --compare-versions "$2" lt-nl "228-5~"; then
done
fi
+# Divert init-d-script with a small wrapper. Do this in postinst and
+# use a symlink to make sure that the init-d-script file is always
+# available never in a state where the original file is diverted away
+# but systemd isn't unpacked.
+if [ "$1" = "configure" ] ; then
+ dpkg-divert --add --package systemd --rename \
+ --divert /lib/init/init-d-script.sysv /lib/init/init-d-script
+ if ! [ -e /lib/init/init-d-script ] ; then
+ ln -s init-d-script.systemd /lib/init/init-d-script
+ fi
+fi
+
#DEBHELPER#
diff --git a/debian/systemd.prerm b/debian/systemd.prerm
index aedbf58e4..8b8f78ac2 100644
--- a/debian/systemd.prerm
+++ b/debian/systemd.prerm
@@ -12,4 +12,14 @@ if [ "$1" = "remove" ] && [ -d /run/systemd/system ]; then
exit 1
fi
+#
+# Remove previous diversion of /lib/init/init-d-script.
+#
+
+if [ "$1" = "remove" ] && [ -L /lib/init/init-d-script ] && [ x"$(readlink -f /lib/init/init-d-script)" = x"/lib/init/init-d-script.systemd" ] ; then
+ rm -f /lib/init/init-d-script
+ dpkg-divert --remove --package systemd --rename \
+ --divert /lib/init/init-d-script.sysv /lib/init/init-d-script
+fi
+
#DEBHELPER#
--
2.11.0
