Clean All Dockers and Configure With Btrfs

So dockers tend to start growing like weeds. And cost me space i don’t have. But one could change the storage driver. You could choose LVM and take advantage of the snapshots or btrfs which i allready have.

Btrfs

Btrfs is a next generation copy-on-write filesystem that supports many advanced storage technologies that make it a good fit for Docker. Btrfs is included in the mainline Linux kernel.

Docker’s btrfs storage driver leverages many Btrfs features for image and container management. Among these features are block-level operations, thin provisioning, copy-on-write snapshots, and ease of administration. You can easily combine multiple physical block devices into a single Btrfs filesystem.

Requirements

  • Install btrfs
  • Make sure you have a volume formated as btrfs (not part of the article)

Clean all dockers and images

# Delete all containers
sudo docker rm $(sudo docker ps -a -q)
# Delete all images
sudo docker rmi $(sudo docker images -q)

Setup

Make sure you have btrfs on your system

sudo cat /proc/filesystems | grep btrfs
  1. Stop docker
sudo service docker stop
  1. Create a backup of you docker settings
sudo mv /var/lib/docker/ /var/lib/docker.bak
  1. create a subvolume from an existing btrfs FS
btrfs subvolume create /archive/dockers

NOTE: It’s better to use a dedicate disk for it

  1. Create the symlink
ln -s /archive/dockers /var/lib/docker
  1. Copy the backup data to the new location
cp -rp /var/lib/docker.bak/* /var/lib/docker/
  1. Configure Docker to use the btrfs storage driver. This is required even though /var/lib/docker/ is now using a Btrfs filesystem. Edit or create the file /etc/docker/daemon.json.
{
  "storage-driver": "btrfs"
}
  1. Start docker service
sudo service docker start
  1. Check if docker is running with docker support
sudo docker info|grep  "Storage Driver"

You could check the volumes being created with the command

sudo btrfs subvolume list /var/liv/docker |grep dockers

References