On Mon, 2012-10-22 at 09:06 +0100, John wrote: > On 22/10/12 03:06, Michael H. Warfield wrote: > > On Mon, 2012-10-22 at 02:53 +0200, Kay Sievers wrote: > >> On Sun, Oct 21, 2012 at 11:25 PM, Michael H. Warfield <mhw@xxxxxxxxxxxx> wrote: > >>> This is being directed to the systemd-devel community but I'm cc'ing the > >>> lxc-users community and the Fedora community on this for their input as > >>> well. I know it's not always good to cross post between multiple lists > >>> but this is of interest to all three communities who may have valuable > >>> input. > >>> > >>> I'm new to this particular list, just having joined after tracking a > >>> problem down to some systemd internals... > >>> > >>> Several people over the last year or two on the lxc-users list have been > >>> discussions trying to run certain distros (notably Fedora 16 and above, > >>> recent Arch Linux and possibly others) in LXC containers, virualizing > >>> entire servers this way. This is very similar to Virtuoso / OpenVZ only > >>> it's using the native Linux cgroups for the containers (primary reason I > >>> dumped OpenVZ was to avoid their custom patched kernels). These recent > >>> distros have switched to systemd for the main init process and this has > >>> proven to be disastrous for those of us using LXC and trying to install > >>> or update our containers. > >>> > >>> To put it bluntly, it doesn't work and causes all sorts of problems on > >>> the host. > >>> > >>> To summarize the problem... The LXC startup binary sets up various > >>> things for /dev and /dev/pts for the container to run properly and this > >>> works perfectly fine for SystemV start-up scripts and/or Upstart. > >>> Unfortunately, systemd has mounts of devtmpfs on /dev and devpts > >>> on /dev/pts which then break things horribly. This is because the > >>> kernel currently lacks namespaces for devices and won't for some time to > >>> come (in design). When devtmpfs gets mounted over top of /dev in the > >>> container, it then hijacks the hosts console tty and several other > >>> devices which had been set up through bind mounts by LXC and should have > >>> been LEFT ALONE. > >>> > >>> Yes! I recognize that this problem with devtmpfs and lack of namespaces > >>> is a potential security problem anyways that could (and does) cause > >>> serious container-to-host problems. We're just not going to get that > >>> fixed right away in the linux cgroups and namespaces. > >>> > >>> How do we work around this problem in systemd where it has hard coded > >>> mounts in the binary that we can't override or configure? Or is it > >>> there and I'm just missing it trying to examine the sources? That's how > >>> I found where the problem lay. > >> As a first step, this probably explains most of it: > >> http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface > > A very long ways, yeah. That looks like it could be just what we've > > been looking for. Just gotta figure out how to set that environment > > variable but that's up to a couple of others to comment on in the > > lxc-users list. Then we'll see where we go from there. > > > > Many thanks! > > > >> Kay > > Regards, > > Mike > > > > I've just performed a very quick check on my Arch Linux system here. > > on host (running systemd): > # cat /proc/1/environ > TERM=linuxRD_TIMESTAMP= > > In a container (running sysvinit): > # cat /proc/1/environ > STY=623.systemd-lithiumTERM=screenTERMCAP=SC|screen|VT 100/ANSI X3.64 > virtual terminal:\ > :DO=\E[%dB:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:bs:bt=\E[Z:\ > :cd=\E[J:ce=\E[K:cl=\E[H\E[J:cm=\E[%i%d;%dH:ct=\E[3g:\ > :do=^J:nd=\E[C:pt:rc=\E8:rs=\Ec:sc=\E7:st=\EH:up=\EM:\ > :le=^H:bl=^G:cr=^M:it#8:ho=\E[H:nw=\EE:ta=^I:is=\E)0:\ > :li#24:co#80:am:xn:xv:LP:sr=\EM:al=\E[L:AL=\E[%dL:\ > :cs=\E[%i%d;%dr:dl=\E[M:DL=\E[%dM:dc=\E[P:DC=\E[%dP:\ > :im=\E[4h:ei=\E[4l:mi:IC=\E[%d@:ks=\E[?1h\E=:\ > :ke=\E[?1l\E>:vi=\E[?25l:ve=\E[34h\E[?25h:vs=\E[34l:\ > :ti=\E[?1049h:te=\E[?1049l:k0=\E[10~:k1=\EOP:k2=\EOQ:\ > :k3=\EOR:k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:\ > :k8=\E[19~:k9=\E[20~:k;=\E[21~:F1=\E[23~:F2=\E[24~:\ > :kh=\E[1~:@1=\E[1~:kH=\E[4~:@7=\E[4~:kN=\E[6~:kP=\E[5~:\ > :kI=\E[2~:kD=\E[3~:ku=\EOA:kd=\EOB:kr=\EOC:kl=\EOD:WINDOW=0SHELL=/bin/shPATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/binLANG=en_GB.UTF-8container=lxc > So it looks like that "container" environment variable is already set on > PID1 Yeah, I saw that myself last night. Testing that out and it's still not working here (although it doesn't seem to be grabbing the host console now) if I use systemd but upstart fires right up and I see that container variable set. Looked like a number of mounts listed on that wiki page. Maybe something is missing. Right now it's just hanging trying to start the container and, when I subsequently try to shut the container down it results in a hung resource and it can't delete the cgroups directory because it's busy. Only thing I did was change the link to /sbin/init from upstart to systemd and it's now dead and I'll have to reboot the host to free the resource. :-P > Regards, > John Regards, Mike -- Michael H. Warfield (AI4NB) | (770) 985-6132 | mhw@xxxxxxxxxxxx /\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/ NIC whois: MHW9 | An optimist believes we live in the best of all PGP Key: 0x674627FF | possible worlds. A pessimist is sure of it!
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