[lxc-devel] symbolic link for /var/lib/lxc

[Serge Hallyn]

Quoting Harald Dunkel (harald.dunkel at aixigo.de):
> Hi folks,
> 
> please consider this:
> 
> # ls -al /var/lib/lxc
> lrwxrwxrwx 1 root root 11 Aug 11  2014 /var/lib/lxc -> /export/lxc
> 
> # lxc-ls --fancy
> NAME          STATE    IPV4           IPV6  GROUPS  AUTOSTART
> -------------------------------------------------------------
> lxchost01     RUNNING  10.123.96.134  -     auto    BY-GROUP
> lxchost02     RUNNING  10.123.99.37   -     auto    BY-GROUP
> lxchost03     RUNNING  10.123.96.51   -     auto    BY-GROUP
> lxchost04     STOPPED  -              -     auto    NO
> lxchost05     RUNNING  10.123.96.46   -     auto    BY-GROUP
> lxchost06     RUNNING  10.123.96.55   -     auto    BY-GROUP
> lxchost07     RUNNING  10.123.99.219  -     auto    BY-GROUP
> lxchost08     RUNNING  10.123.96.53   -     auto    BY-GROUP
> lxchost09     RUNNING  10.123.96.76   -     auto    BY-GROUP
> lxchost10     RUNNING  10.123.99.216  -     auto    BY-GROUP
> lxchost11     RUNNING  10.123.99.125  -     auto    BY-GROUP
> lxchost12     STOPPED  -              -     -       NO
> 
> # lxc-ls -P /export/lxc --fancy
> NAME          STATE    IPV4  IPV6  GROUPS  AUTOSTART
> ----------------------------------------------------
> lxchost01     STOPPED  -     -     auto    BY-GROUP
> lxchost02     STOPPED  -     -     auto    BY-GROUP
> lxchost03     STOPPED  -     -     auto    BY-GROUP
> lxchost04     STOPPED  -     -     auto    NO
> lxchost05     STOPPED  -     -     auto    BY-GROUP
> lxchost06     STOPPED  -     -     auto    BY-GROUP
> lxchost07     STOPPED  -     -     auto    BY-GROUP
> lxchost08     STOPPED  -     -     auto    BY-GROUP
> lxchost09     STOPPED  -     -     auto    BY-GROUP
> lxchost10     STOPPED  -     -     auto    BY-GROUP
> lxchost11     STOPPED  -     -     auto    BY-GROUP
> lxchost12     STOPPED  -     -     -       NO
> 
> 
> This looks pretty fragile to me. Shouldn't lxc report the same
> state for both paths, no matter what?

No, because when you start the container, it listens on a
abstract unix socket, i.e. @/var/lib/lxc/rootw1/command, for
things like 'what is your init pid'.  The lxcpath is a part of
that path.  So when you callously do lxc-ls using a different
lxcpath than you used for lxc-start, you end up looking for
a command socket which doesn't exist.

Since a container named 'lxchost01' could exist and be running
in 5 different lxcpaths at the same time, we can't really avoid
this.  (that is, it has to be the case that the lxcpath matters)

-serge