starting jails in the background & dependencies

[Simon L. Nielsen]

B0;251;0cOn 2010.01.14 13:35:16 +0100, Alexander Leidinger wrote:
> Quoting Remko Lodder <remko at FreeBSD.org> (from Tue, 5 Jan 2010  
> 11:35:48 +0100):
> 
> > On Tue, January 5, 2010 11:24 am, Alexander Leidinger wrote:
> >> On Mon, 07 Dec 2009 08:03:53 +0100 Alexander Leidinger
> >> <Alexander at Leidinger.net> wrote:
> >>
> >>> Hi,
> >>>
> >>> now that jails are started in the background (which is good, to
> >>
> >> I just realized yesterday that it also stops in parallel (in the
> >> background). This is bad. It may be the case that a jail is not fully
> >> stopped via the rc scripts when the OS decides to kill the remaining
> >> processes during a shutdown.
> >>
> >> My first reaction is to only allow to start in the background, but
> >> everything else needs to be serialized.
> >>
> >> Any objections or better ideas out there?
> 
> > I think the best way at this moment is to revert the change ( I can do
> > that , or someone else, I dont mind ) and think of a better concept. Simon
> > also mentioned that he didn't like the current way of doing things, so I
> > kept it in, for possible suggestions. Reverting the change would mean that
> > the old behaviour at least works and is with what people are used to. We
> > can then further improve it where needed.
> 
> What about the following? Just have a look at the principle, I haven't  
> tested it yet. What it does is:
>   - revert back to serial startup by default
>   - allow to only start in the background (jail_parallel_start=YES)

In some thread there was talk about parallel stop as well, but I must
admit I never looked at it.

>   - take input from /dev/null: in case a start script inside the
>     jail wants to read from stdin (it shouldn't), it will not
>     switch the process into STOP state (but should generate some
>     message in the application log)

This seems like a fine change - especially since the output from the
actual jail is hidden.

> Copy&paste, so maybe messed up tabs:

The bottom part of rc.d/jail after the patch seems.... well, "messy"
in lack of a better word, but since I can't come up with a better
solution right now I think this patch should be committed, and then we
can always improve the implementation later.

Note that I haven't tsted it, but I don't see any errors in the patch.

> ---snip---
> Index: share/man/man5/rc.conf.5
> ===================================================================
> --- share/man/man5/rc.conf.5    (Revision 202277)
> +++ share/man/man5/rc.conf.5    (Arbeitskopie)
> @@ -24,7 +24,7 @@
>   .\"
>   .\" $FreeBSD$
>   .\"
> -.Dd November 11, 2009
> +.Dd January 14, 2010
>   .Dt RC.CONF 5
>   .Os
>   .Sh NAME
> @@ -3472,6 +3472,11 @@
>   If set to
>   .Dq Li NO ,
>   any configured jails will not be started.
> +.It jail_parallel_start
> +.Pq Vt bool
> +If set to
> +.Dq Li YES
> +all configured jails will be started in the background (= in parallel).
>   .It Va jail_list
>   .Pq Vt str
>   A space separated list of names for jails.
> Index: etc/rc.d/jail
> ===================================================================
> --- etc/rc.d/jail       (Revision 202277)
> +++ etc/rc.d/jail       (Arbeitskopie)
> @@ -636,7 +636,8 @@
>                  done
> 
>                  eval ${_setfib} jail ${_flags} -i ${_rootdir} ${_hostname} \
> -                       \"${_addrl}\" ${_exec_start} > ${_tmp_jail} 2>&1
> +                       \"${_addrl}\" ${_exec_start} > ${_tmp_jail} 2>&1 \
> +                       </dev/null
> 
>                  if [ "$?" -eq 0 ] ; then
>                          _jail_id=$(head -1 ${_tmp_jail})
> @@ -728,4 +729,19 @@
>   if [ -n "$*" ]; then
>          jail_list="$*"
>   fi
> -run_rc_command "${cmd}" &
> +
> +# Only allow the parallel start of jails, other commands are not
> +# safe to execute in parallel.
> +case "${cmd}" in
> +*start)
> +       ;;
> +*)
> +       jail_parallel_start=NO
> +esac
> +
> +if checkyesno jail_parallel_start; then
> +       run_rc_command "${cmd}" &
> +else
> +       run_rc_command "${cmd}"
> +fi
> +
> Index: etc/defaults/rc.conf
> ===================================================================
> --- etc/defaults/rc.conf        (Revision 202277)
> +++ etc/defaults/rc.conf        (Arbeitskopie)
> @@ -630,6 +630,7 @@
>   ### Jail Configuration #######################################
>   ##############################################################
>   jail_enable="NO"       # Set to NO to disable starting of any jails
> +jail_parallel_start="NO"       # Start jails in the background
>   jail_list=""           # Space separated list of names of jails
>   jail_set_hostname_allow="YES" # Allow root user in a jail to change  
> its hostname
>   jail_socket_unixiproute_only="YES" # Route only TCP/IP within a jail
> ---snip---

-- 
Simon L. Nielsen