Runc

This article provides an overview of CRIU integration with runc and explains how to use it.

Container Checkpoint/Restore

Create a container rootfs

mkdir -p alpine-container/rootfs && cd alpine-container
wget https://dl-cdn.alpinelinux.org/alpine/latest-stable/releases/x86_64/alpine-minirootfs-3.22.2-x86_64.tar.gz
tar -xzf alpine-minirootfs-3.22.2-x86_64.tar.gz -C rootfs
rm -f alpine-minirootfs-3.22.2-x86_64.tar.gz

Create a container specification file:

runc spec

Set a command to run in the container:

sed -i 's/"sh"/"sh", "-c", "i=0; while true; do echo $i; i=$(expr $i + 1); sleep 1; done"/' config.json

Start the container and redirect the output/error to looper.out and looper.out:

sudo runc run looper 0</dev/null 1>looper.out 2>looper.err &

Alternatively, you can disable the interactive terminal and run container in the background as follows:

sed -i 's/"terminal": true/"terminal": false/g' config.json
sudo runc run -d looper 0</dev/null 1>/dev/null 2>/dev/null

Show running containers

sudo runc list
sudo runc state looper

Now the container can be checkpointed:

mkdir /tmp/checkpoint
sudo runc checkpoint --image-path /tmp/checkpoint --work-path /tmp/checkpoint looper

Once the container is checkpointed it will be no longer visible in runc list.

The following command can be used to restore the container:

sudo runc restore --image-path /tmp/checkpoint --work-path /tmp/checkpoint looper

Show running containers:

sudo runc list
sudo runc state looper

The following command can be used to terminate the running container:

sudo runc kill looper KILL
sudo runc delete looper