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Line 47: − − Work is in progress to add native checkpoint and restore support − to Docker. Once ready, specific commands (for example, "docker − checkpoint" and "docker restore") will use CRIU to do the actual − C/R operations while Docker continues to maintain its parent-child − relationship and container states. Line 74:
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minor formatting fixes + rm obsolete paragraph
watch this short demo
watch this short demo
'''[https://www.youtube.com/watch?v=HFt9v6yqsXo video]'''
'''[https://www.youtube.com/watch?v=HFt9v6yqsXo video]'''
to see how it works. Source files for Docker 1.5 C/R is at this
to see how it works. Source files for Docker 1.5 C/R are at this
'''[https://github.com/SaiedKazemi/docker/tree/cr repo]'''.
'''[https://github.com/SaiedKazemi/docker/tree/cr repo]'''.
The '''[https://github.com/SaiedKazemi/docker/wiki wiki]'''
The '''[https://github.com/SaiedKazemi/docker/wiki wiki]'''
page provides an overview of the project history.
page provides an overview of the project history.
Work in underway to integrate C/R into the new libcontainer.
Work in underway to integrate C/R into the new <code>libcontainer</code>.
For native C/R support, additional functionality was added to CRIU.
For native C/R support, additional functionality was added to CRIU.
== External C/R ==
== External C/R ==
Starting with CRIU 1.3, it's possible to checkpoint and restore a
Starting with CRIU 1.3, it is possible to checkpoint and restore a
process tree running inside a Docker container. However, it's
process tree running inside a Docker container. However, it's
important to note that Docker needs native support for checkpoint
important to note that Docker needs native support for checkpoint
child of Docker and, from Docker's point of view, the container's
child of Docker and, from Docker's point of view, the container's
state will remain "Exited" (even after successful restore).
state will remain "Exited" (even after successful restore).
It's important to re-emphasize that by checkpointing and restoring
It's important to re-emphasize that by checkpointing and restoring
However, because Docker by default uses the AUFS graph driver and
However, because Docker by default uses the AUFS graph driver and
the AUFS module in the kernel reveals branch pathnames in
the AUFS module in the kernel reveals branch pathnames in
/proc/<pid>/map_files, --root is used to specify the root of the
<code>/proc/''pid''/map_files</code>, option <code>--root</code>
is used to specify the root of the
mount namespace. Once the kernel AUFS module is fixed, it won't
mount namespace. Once the kernel AUFS module is fixed, it won't
be necessary to specify this option anymore.
be necessary to specify this option anymore.
This option is used to specify the path of the external bind mounts.
This option is used to specify the path of the external bind mounts.
Docker sets up /etc/{hostname,hosts,resolv.conf} as targets with
Docker sets up <code>/etc/{hostname,hosts,resolv.conf}</code> as targets with
source files outside the container's mount namespace. Older versions
source files outside the container's mount namespace. Older versions
of Docker also bind mount /.dockerinit.
of Docker also bind mount <code>/.dockerinit</code>.
For example, assuming the default Docker configuration, /etc/hostname
For example, assuming the default Docker configuration, <code>/etc/hostname</code>
in the container's mount namespace is bind mounted from the source
in the container's mount namespace is bind mounted from the source
at /var/lib/docker/containers/<container_id>/hostname.
at <code>/var/lib/docker/containers/''container_id''/hostname</code>.
=== <code>--manage-cgroups</code> ===
=== <code>--manage-cgroups</code> ===
=== <code>--evasive-devices</code> ===
=== <code>--evasive-devices</code> ===
Docker bind mounts /dev/null on /dev/stdin for detached containers
Docker bind mounts <code>/dev/null</code> on <code>/dev/stdin</code> for detached containers
(i.e., docker run -d ...). Since earlier versions of Docker used
(i.e., <code>docker run -d ...</code>). Since earlier versions of Docker used
/dev/null in the global namespace, this option tells CRIU to treat
<code>/dev/null</code> in the global namespace, this option tells CRIU to treat
the global /dev/null and the container /dev/null as the same device.
the global <code>/dev/null</code> and the container <code>/dev/null</code> as the same device.
== Restore Prework ==
== Restore Prework ==
As mentioned earlier, by default Docker uses AUFS to set up the
As mentioned earlier, by default Docker uses AUFS to set up the
container's filesystem. When Docker notices that the process has
container's filesystem. When Docker notices that the process has
exited (due to criu dump), it dismantles the filesystem. We need
exited (due to CRIU dump), it dismantles the filesystem. We need
to set up the filesystem again before attempting to restore.
to set up the filesystem again before attempting to restore.
</pre>
</pre>
Optionally, you can specify -v to see the commands that docker_cr.sh
Optionally, you can specify <code>-v</code> to see the commands that <code>docker_cr.sh</code>
executes. For example:
executes. For example: