Simple script to backup LXC containers

lxc-backup.sh

#!/usr/bin/env bash
set -ex

BACKUP_DIR=/path/to/where/backups/should/live
HOSTS=($(lxc list -c n --format csv))

for HOST in "${HOSTS[@]}"
do
    BACKUP_NAME=${HOST}-$(date +"%Y-%m-%d")

    lxc snapshot ${HOST} auto-backup
    lxc publish ${HOST}/auto-backup --alias ${BACKUP_NAME}
    lxc image export ${BACKUP_NAME} ${BACKUP_DIR}/${BACKUP_NAME}
    lxc image delete ${BACKUP_NAME}
    lxc delete ${HOST}/auto-backup
done

Tested today and importing on another host works with this sequence:

# Import the image
lxc image import <tarball> --alias <image_alias>
# Create the container from the image
lxc init <image_alias> <container_name>
# Start the container
lxc start <container_name>

For example, I started my nginx container on a new host with:

lxc image import nginx-2020-01-01.tar.gz.tar.gz --alias nginx-copy
lxc init nginx-copy nginx-copy
lxc start nginx-copy

I use UFW rules to route from the host interface to the container setup the rules:

# /etc/ufw/before.rules
*nat
:PREROUTING ACCEPT [0:0]
# nginx container
-A PREROUTING -i eno1 -p tcp --dport 80 -j DNAT --to <container_ip>:80
-A PREROUTING -i eno1 -p tcp --dport 443 -j DNAT --to <container_ip>:443

COMMIT

# Remainder of file unchanged

…and turn on UFW:

sudo ufw enable

When I edit /etc/ufw/before.rules, I use this one-liner to reload the firewall rules:

for i in $( sudo iptables -t nat --line-numbers -L | grep ^[0-9] | awk '{ print $1 }' | tac ); do sudo iptables -t nat -D PREROUTING $i; done; sudo ufw reload

Awesome :)

One question though.. Will this also re add devices back to the container's config that you've added with:
lxc config device add c1 sharedwww disk source=/wwwdata/ path=/var/www/html/