lxc-shutdown: Make all processes exit before timeout if shutdown works

The following rationale is for using the -t option:

Currently, lxc-shutdown uses a subprocess for the timeout handling,
where a 'sleep $TIMEOUT' is executed, which will kill the main process
after the timeout has occurred, thus causing the main process to stop
the container hard with lxc-stop.

On the other hand, if the timeout is not reached, the main process
kills the subprocess. The trouble now is that if you kill a shell that
is running in the background, the kill will only take effect as soon as
the program currently running in the shell exits.

This in turn means that the subprocess will never terminate before
reaching the timeout. In an interactive shell, this does not matter,
since people will just not notice the process and lxc-shutdown returns
immediately. In a non-interactive enironment, however, there may be
circumstances that cause the calling program to wait until even that
subprocess is terminated, which means that shutdown will always take as
long as the timeout, even if the container shuts down quite a bit
earlier.

This change makes sure that also all subprocesses of the background
process are killed from the main process. This will immediately
terminate the background process, thus ensuring the desired behaviour.

Signed-off-by: Christian Seiler <christian@iwakd.de>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
lxc-attach: Implement --clear-env and --keep-env

This patch introduces the --clear-env and --keep-env options for
lxc-attach, that allows the user to specify whether the environment
should be passed on inside the container or not.

This is to be expanded upon in later versions, this patch only
introduces the most basic functionality.

Signed-off-by: Christian Seiler <christian@iwakd.de>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
lxc-create: require absolute path for non-standard templates

Otherwise, as an example, if doing 'lxc-create -t debian' while
there is a 'debian' directory, lxc-create will fail to do the
right thing.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
Make lxc.functions return the default lxcpath if /etc/lxc/lxc.conf doesn't provide one

Currently it returns the default path only if /etc/lxc/lxc.conf missing.
Since default lxc.conf doesn't contain lxcpath variable (this is at least the case in ubuntu) all tools fails if one doesn't give -P

caglar@qgq:~/Project/lxc/examples$ sudo /usr/bin/lxc-create -n test
lxc-create: no configuration path defined

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
API shouldn't be calling create for already defined containers or destroy for non defined ones

Currently it always calls create/destroy which might be confusing for the code
that checks the return value of those calls to determine whether operation
completed successfully or not.

>>> c = lxc.Container("r")
>>> c.create("ubuntu")
True
>>> c.create("ubuntu")
True
>>> c.create("ubuntu")
True
>>> c.create("ubuntu")
True
>>> c.create("ubuntu")
>>> c.destroy()
True
>>> c.destroy()
lxc-destroy: 'r' does not exist
False
>>> c.destroy()
lxc-destroy: 'r' does not exist
False

New behaviour

>>> c = lxc.Container("r")
>>> c.create('ubuntu')
True
>>> c.create('ubuntu')
False
>>> c.destroy()
True
>>> c.destroy()
False
>>>

Tested with following script;

import lxc
c = lxc.Container("abcdef")
print ("set", c.set_config_item("lxc.utsname", "abcdef"))
print ("save", c.save_config())
print ("create", c.create("ubuntu"))
print ("create", c.create("ubuntu"))
print ("destroy", c.destroy())
print ("destroy", c.destroy())
print ("set", c.set_config_item("lxc.utsname", "abcdef"))
print ("save", c.save_config())
print ("destroy", c.destroy())
print ("destroy", c.destroy())

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>