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{{Warning|External C/R was done as a proof-of-concept. Do not use it; please see [[Docker]] for a proper way to do checkpoint/restore with Docker. This article is kept here for historical purposes and some background info.}}
{{Note| External C/R was done as proof-of-concept. Its use is discouraged and the helper script mentioned below may break in the near future.}}
This approach is called external because it's happening external to the
This approach is called external because it's happening external to the
include the Docker daemon which runs in the global PID namespace.
include the Docker daemon which runs in the global PID namespace.
== Command Line Options ==
In addition to the usual CRIU command line options used when
In addition to the usual CRIU command line options used when
line options are needed for Docker containers.
line options are needed for Docker containers.
=== <code>--root</code> ===
This option has been used in the past only for restore operations
This option has been used in the past only for restore operations
be necessary to specify this option anymore.
be necessary to specify this option anymore.
=== <code>--ext-mount-map</code> ===
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.
at <code>/var/lib/docker/containers/''container_id''/hostname</code>.
at <code>/var/lib/docker/containers/''container_id''/hostname</code>.
=== <code>--manage-cgroups</code> ===
When a process tree exits after a checkpoint operation, the cgroups
When a process tree exits after a checkpoint operation, the cgroups
re-creating them if necessary.
re-creating them if necessary.
=== <code>--evasive-devices</code> ===
Docker bind mounts <code>/dev/null</code> on <code>/dev/stdin</code> for detached containers
Docker bind mounts <code>/dev/null</code> on <code>/dev/stdin</code> for detached containers
the global <code>/dev/null</code> and the container <code>/dev/null</code> as the same device.
the global <code>/dev/null</code> and the container <code>/dev/null</code> as the same device.
=== <code>--inherit-fd</code> ===
For native C/R support, this option tells CRIU to let the restored process "inherit"
For native C/R support, this option tells CRIU to let the restored process "inherit"
its specified file descriptor (instead of restoring from checkpoint).
its specified file descriptor (instead of restoring from checkpoint).
== Restore Prework for External C/R ==
Docker supports many storage drivers (AKA graph drivers) including
Docker supports many storage drivers (AKA graph drivers) including
filesystem again before attempting to restore.
filesystem again before attempting to restore.
== An External C/R Example ==
Below is an example to show C/R operations for a shell script that
Below is an example to show C/R operations for a shell script that
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== External C/R Helper Script ==
As seen in the above examples, the CRIU command line for checkpointing and
As seen in the above examples, the CRIU command line for checkpointing and
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== See also ==
* [[Docker]]
[[Category:HOWTO]]
[[Category:HOWTO]]