Posted by one friend in comments
Hi Slava, sorry that your question was closed. For the record, Slava is talking about docker.io, a runtime for linux containers. Yes, docker export is a suitable approach. It will generate a tarball of your entire container filesystem state, and dump it on stdout. So
docker export $CONTAINER_ID > $CONTAINER_ID-backup.tar
will yield a usable tarball. You can re-import the tarball with
docker import - slava/$CONTAINER_ID-backup < $CONTAINER_ID-backup.tar
Note the original metadata (eg id of the original image) will be lost. This should be fixed in future versions of docker.
– Solomon Hykes Apr 2 ’13 at 6:35
Adding here so one can find from summary that question was answered. Thanks Solomon!