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Make normal general description
$ lxc-start -n test-lxc
$ lxc-start -n test-lxc
= Dump/Restore a Linux Container =
= Checkpoint and restore an LXC Container =
==[[Installation]]==
== Preparations ==
The installation process is described [[Installation | here]].
You only need to [[Installation | install]] the crtools.
==Example==
== Dump and restore ==
Dumping and restoring an LXC contianer means -- dumping a subtree of processes starting from container init plus all kinds of namespaces.
Restoring is symmetrical. The way LXC container works imposes some more requirements on crtools usage.
* You need to use the <code>--evasive-devices</code> option to handle <code>/dev/log</code> users (there's a bug in LXC code)
* In order to properly isolate container from unwanted networking communication during checkpoint/restore you should provide a script for locking/unlocking the container network (see below)
* When restoring a container with veth device you may specify a name for the host-side veth device
* In order to checkpoint and restore alive TCP connections you should use the <code>--tcp-established</code> option
Typically a container dump command will look like
<pre>
crtools dump
--evasive-devices # handle /dev/log usage bug
--tcp-established # allow for TCP connections dump
-n net -n mnt -n ipc -n pid # dump all the namespaces container uses
--action-script "net-script.sh" # use net-script.sh to lock/unlock networking
-D dump/ -o dump.log # set images dir to dump/ and put logs into dump.log file
-t ${init-pid} # start dumping from task ${init-pid}. It should be container's init
</pre>
and restore command like
<pre>
crtools restore
--evasive-devices
--tcp-established
-n net -n mnt -n ipc -n pid
--action-script "net-script.sh"
--veth-pair eth0=${veth-name} # when restoring a veth link use ${veth-name} for host-side device end
--root ${path} # path to container root. It should be a root of a (bind)mount
-D data/ -o restore.log
-t ${init-pid}
</pre>
We also find it useful to use the <code>--restore-detached</code> option for restore to make contianer reparent to init rather than hanging on a crtools process launched from shell. Another useful option is the <code>--pidfile</code> one -- you will be able to find out the host-side pid of a container init after restore.
== Example ==
We have [http://git.criu.org/?p=crtools.git;a=tree;f=test/app-emu/lxc;hb=HEAD an application test] to test dump/restore of a Linux Container.
We have [http://git.criu.org/?p=crtools.git;a=tree;f=test/app-emu/lxc;hb=HEAD an application test] to test dump/restore of a Linux Container.