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The Kubernetes kubelet creates checkpoints which consists of metadata (checkpointed.pods) and tar archives containing the actual pod checkpoints.

With the help of this tool (checkpointctl) it is possible to display, extract or insert checkpoints.

To display the checkpoints which are currently in the kubelet's default checkpoint directory just use checkpointctl show:

$ checkpointctl show

Displaying data from /var/lib/kubelet/checkpoints/checkpointed.pods

+-----------+-----------+-----------+-----------------------------------+---------------+
|    POD    | NAMESPACE | CONTAINER |               IMAGE               | ARCHIVE FOUND |
+-----------+-----------+-----------+-----------------------------------+---------------+
| my-redis  | default   | redis     | redis                             | true          |
+-----------+           +-----------+-----------------------------------+               +
| counters  |           | counter   | quay.io/adrianreber/counter       |               |
+           +           +-----------+-----------------------------------+               +
|           |           | wildfly   | quay.io/adrianreber/wildfly-hello |               |
+-----------+-----------+-----------+-----------------------------------+---------------+

To extract all checkpoints from the kubelet use:

$ checkpointctl extract -o /tmp/checkpoints.tar

Extracting checkpoint data from /var/lib/kubelet/checkpoints/checkpointed.pods

Resulting in a tar archive at /tmp/checkpoints.tar which can then be used to insert this checkpoint archive into another kubelet:

$ checkpointctl insert -i /tmp/checkpoints.tar

Inserting a checkpoint archive will add the new checkpoints to existing checkpoints.

All operations default to /var/lib/kubelet/checkpoints which can be changed using the --target parameter.

The command checkpointctl show can also be used on an exported tar archive to see which checkpoints are part of an exported tar archive:

$ checkpointctl show --target /tmp/checkpoints.tar

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