buttervolume 3.10

Description:

buttervolume 3.10

BTRFS Volume plugin for Docker
What will Buttervolume allow you to do?

Quickly recover recent data after an exploit or failure of your web sites or applications
Quickly rollback your data to a previous version after a failed upgrade
Implement automatic upgrade of your applications without fear
Keep an history of your data
Make many backups without consuming more disk space than needed
Build a resilient hosting cluster with data replication
Quickly move your applications between nodes
Create preconfigured or templated applications to deploy in seconds

What can Buttervolume do?

Snapshot your Docker volumes
Restore a snapshot to its original volume or under a new volume
List and remove existing snapshots of your volumes
Clone your Docker volumes
Replicate or Sync your volumes to another host
Schedule periodic snapshots, sync or replication of your volumes
Schedule periodic removal of your old snapshots

How does it work?
Buttervolume is a Docker Volume Plugin that sits on top of a BTRFS partition
and can manage and replicate BTRFS snapshots of your Docker volumes.

Contents

BTRFS Volume plugin for Docker

Introduction
Prerequisites
Build and run as a contributor
Install and run as a user
Upgrade
Configure
Usage

Running the plugin
Running the plugin locally or in legacy mode
Creating and deleting volumes
Managing volumes and snapshots
Create a snapshot
List the snapshots
Restore a snapshot
Clone a volume
Delete a snapshot
Replicate a snapshot to another host
Synchronize a volume from another host volume
Purge old snapshots
Schedule a job
List scheduled jobs
Copy-on-write


Testing
Working without a BTRFS partition
Migrate to version 3
Credits


CHANGELOG

3.10 (2023-04-09)
3.9 (2022-10-11)
3.8 (2022-10-07)
3.7 (2018-12-13)
3.6 (2018-12-11)
3.5 (2018-06-07)
3.4 (2018-04-27)
3.3 (2018-04-27)
3.2 (2018-04-27)
3.1 (2018-04-27)
3.0 (2018-04-24)
2.0 (2018-03-24)
1.4 (2018-02-01)
1.3.1 (2017-10-22)
1.3 (2017-07-30)
1.2 (2017-07-16)
1.1 (2017-07-13)
1.0 (2017-05-24)





Introduction
BTRFS is a next-generation copy-on-write
filesystem with subvolume and snapshot support. A BTRFS subvolume can be
seen as an independant file namespace that can live in a directory and can be
mounted as a filesystem and snapshotted individually.
On the other hand, Docker volumes are commonly used
to store persistent data of stateful containers, such as a MySQL/PostgreSQL
database or an upload directory of a CMS. By default, Docker volumes are just
local directories in the host filesystem. A number of Volume plugins
already exist for various storage backends, including distributed filesystems,
but small clusters often can’t afford to deploy a distributed filesystem.
We believe BTRFS subvolumes are a powerful and lightweight storage solution for
Docker volumes, allowing fast and easy replication (and backup) across several
nodes of a small cluster.


Prerequisites
Make sure the directory /var/lib/buttervolume/ is living in a BTRFS
filesystem. It can be a BTRFS mountpoint or a BTRFS subvolume or both.
You should also create the directories for the config and ssh on the host:
sudo mkdir /var/lib/buttervolume
sudo mkdir /var/lib/buttervolume/config
sudo mkdir /var/lib/buttervolume/ssh


Build and run as a contributor
If you want to be a contributor, read this chapter. Otherwise jump to the next section.
You first need to create a root filesystem for the plugin, using the provided Dockerfile:
git clone https://github.com/anybox/buttervolume
./build.sh
By default the plugin is built for the latest commit (HEAD). You can build another version by specifying it like this:
./build.sh 3.7
At this point, you can set the SSH_PORT option for the plugin by running:
docker plugin set anybox/buttervolume SSH_PORT=1122
Note that this option is only relevant if you use the replication feature between two nodes.
Now you can enable the plugin, which should start buttervolume in the plugin
container:
docker plugin enable anybox/buttervolume:HEAD
You can check it is responding by running a buttervolume command:
export RUNCROOT=/run/docker/runtime-runc/plugins.moby/ # or /run/docker/plugins/runtime-root/plugins.moby/
alias drunc="sudo runc --root $RUNCROOT"
alias buttervolume="drunc exec -t $(drunc list|tail -n+2|awk '{print $1}') buttervolume"
sudo buttervolume scheduled
Increase the log level by writing a /var/lib/buttervolume/config/config.ini file with:
[DEFAULT]
TIMER = 120
Then check the logs with:
sudo journalctl -f -u docker.service
You can also locally install and run the plugin in the foreground with:
python3 -m venv venv
./venv/bin/python setup.py develop
sudo ./venv/bin/buttervolume run
Then you can use the buttervolume CLI that was installed in developer mode in the venv:
./venv/bin/buttervolume --version


Install and run as a user
If the plugin is already pushed to the image repository, you can install it with:
docker plugin install anybox/buttervolume
Check it is running:
docker plugin ls
Find your runc root, then define useful aliases:
export RUNCROOT=/run/docker/runtime-runc/plugins.moby/ # or /run/docker/plugins/runtime-root/plugins.moby/
alias drunc="sudo runc --root $RUNCROOT"
alias buttervolume="drunc exec -t $(drunc list|tail -n+2|awk '{print $1}') buttervolume"
And try a buttervolume command:
buttervolume scheduled
Or create a volume with the driver. Note that the name of the driver is the
name of the plugin:
docker volume create -d anybox/buttervolume:latest myvolume
Note that instead of using aliases, you can also define functions that you
can put in your .bash_profile or .bash_aliases:
function drunc () {
RUNCROOT=/run/docker/runtime-runc/plugins.moby/ # or /run/docker/plugins/runtime-root/plugins.moby/
sudo runc --root $RUNCROOT $@
}
function buttervolume () {
drunc exec -t $(docker plugin ls --no-trunc | grep 'anybox/buttervolume:latest' | awk '{print $1}') buttervolume $@
}


Upgrade
You must force disable it before reinstalling it (as explained in the docker documentation):
docker plugin disable -f anybox/buttervolume
docker plugin rm -f anybox/buttervolume
docker plugin install anybox/buttervolume


Configure
You can configure the following variables:


DRIVERNAME: the full name of the driver (with the tag)
VOLUMES_PATH: the path where the BTRFS volumes are located
SNAPSHOTS_PATH: the path where the BTRFS snapshots are located
TEST_REMOTE_PATH: the path during unit tests where the remote BTRFS snapshots are located
SCHEDULE: the path of the scheduler configuration
RUNPATH: the path of the docker run directory (/run/docker)
SOCKET: the path of the unix socket where buttervolume listens
TIMER: the number of seconds between two runs of the scheduler
DTFORMAT: the format of the datetime in the logs
LOGLEVEL: the Python log level (INFO, DEBUG, etc.)


The configuration can be done in this order of priority:


from an environment variable prefixed with BUTTERVOLUME_ (ex: BUTTERVOLUME_TIMER=120)
from the [DEFAULT] section of the /etc/buttervolume/config.ini file
inside the container or /var/lib/buttervolume/config/config.ini on the
host


Example of config.ini file:
[DEFAULT]
TIMER = 120
If none of this is configured, the following default values are used:


DRIVERNAME = anybox/buttervolume:latest
VOLUMES_PATH = /var/lib/buttervolume/volumes/
SNAPSHOTS_PATH = /var/lib/buttervolume/snapshots/
TEST_REMOTE_PATH = /var/lib/buttervolume/received/
SCHEDULE = /etc/buttervolume/schedule.csv
RUNPATH = /run/docker
SOCKET = $RUNPATH/plugins/btrfs.sock # only if run manually
TIMER = 60
DTFORMAT = %Y-%m-%dT%H:%M:%S.%f
LOGLEVEL = INFO




Usage

Running the plugin
The normal way to run it is as a new-style Docker Plugin as described above in
the “Install and run” section, which will start it automatically. This will
create a /run/docker/plugins/<uuid>/btrfs.sock file to be used by the
Docker daemon. The <uuid> is the unique identifier of the runc/OCI
container running it. This means you can probably run several versions of the
plugin simultaneously but this is currently not recommended unless you keep in
mind the volumes and snapshots are in the same place for the different
versions. Otherwise you can configure a different path for the volumes and
snapshots of each different versions using the config.ini file.
Then the name of the volume driver is the name of the plugin:
docker volume create -d anybox/buttervolume:latest myvolume
or:
docker volume create --volume-driver=anybox/buttervolume:latest
When creating a volume, you can choose to disable copy-on-write on a per-volume
basis. Just use the -o or –opt option as defined in the Docker documentation
docker volume create -d anybox/buttervolume -o copyonwrite=false myvolume


Running the plugin locally or in legacy mode
If you installed it locally as a Python distribution, you can also
start it manually with:
sudo buttervolume run
In this case it will create a unix socket in /run/docker/plugins/btrfs.sock
for use by Docker with the legacy plugin system. Then the name of the volume
driver is the name of the socket file:
docker volume create -d btrfs myvolume
or:
docker create --volume-driver=btrfs
When started, the plugin will also start its own scheduler to run periodic jobs
(such as a snapshot, replication, purge or synchronization)


Creating and deleting volumes
Once the plugin is running, whenever you create a container you can specify the
volume driver with docker create --volume-driver=btrfs --name <name> <image>. You can also manually create a BTRFS volume with docker volume create -d btrfs. It also works with docker-compose, by specifying the
btrfs driver in the volumes section of the compose file.
When you delete the volume with docker rm -v <container> or docker volume rm <volume>, the BTRFS subvolume is deleted. If you snapshotted the volume
elsewhere in the meantime, the snapshots won’t be deleted.


Managing volumes and snapshots
When buttervolume is installed, it provides a command line tool
buttervolume, with the following subcommands:
run Run the plugin in foreground
snapshot Snapshot a volume
snapshots List snapshots
schedule (un)Schedule a snapshot, replication or purge
scheduled List scheduled actions
restore Restore a snapshot (optionally to a different volume)
clone Clone a volume as new volume
send Send a snapshot to another host
sync Synchronise a volume from a remote host volume
rm Delete a snapshot
purge Purge old snapshot using a purge pattern


Create a snapshot
You can create a readonly snapshot of the volume with:
buttervolume snapshot <volume>
The volumes are currently expected to live in /var/lib/buttervolume/volumes and
the snapshot will be created in /var/lib/buttervolume/snapshots, by appending the
datetime to the name of the volume, separated with @.


List the snapshots
You can list all the snapshots:
buttervolume snapshots
or just the snapshots corresponding to a volume with:
buttervolume snapshots <volume>
<volume> is the name of the volume, not the full path. It is expected
to live in /var/lib/buttervolume/volumes.


Restore a snapshot
You can restore a snapshot as a volume. The current volume will first
be snapshotted, deleted, then replaced with the snapshot. If you provide a
volume name instead of a snapshot, the latest snapshot is restored. So no
data is lost if you do something wrong. Please take care of stopping the
container before restoring a snapshot:
buttervolume restore <snapshot>
<snapshot> is the name of the snapshot, not the full path. It is expected
to live in /var/lib/buttervolume/snapshots.
By default, the volume name corresponds to the volume the snapshot was created
from. But you can optionally restore the snapshot to a different volume name by
adding the target as the second argument:
buttervolume restore <snapshot> <volume>


Clone a volume
You can clone a volume as a new volume. The current volume will be cloned
as a new volume name given as parameter. Please take care of stopping the
container before cloning a volume:
buttervolume clone <volume> <new_volume>
<volume> is the name of the volume to be cloned, not the full path. It is expected
to live in /var/lib/buttervolume/volumes.
<new_volume> is the name of the new volume to be created as clone of previous one,
not the full path. It is expected to be created in /var/lib/buttervolume/volumes.


Delete a snapshot
You can delete a snapshot with:
buttervolume rm <snapshot>
<snapshot> is the name of the snapshot, not the full path. It is expected
to live in /var/lib/buttervolume/snapshots.


Replicate a snapshot to another host
You can incrementally send snapshots to another host, so that data is
replicated to several machines, allowing to quickly move a stateful docker
container to another host. The first snapshot is first sent as a whole, then
the next snapshots are used to only send the difference between the current one
and the previous one. This allows to replicate snapshots very often without
consuming a lot of bandwith or disk space:
buttervolume send <host> <snapshot>
<snapshot> is the name of the snapshot, not the full path. It is expected
to live in /var/lib/buttervolume/snapshots and is replicated to the same path on
the remote host.
<host> is the hostname or IP address of the remote host. The snapshot is
currently sent using BTRFS send/receive through ssh, with an ssh server direcly
included in the plugin. This requires that ssh keys be present and already
authorized on the target host (under /var/lib/buttervolume/ssh), and that
the StrictHostKeyChecking no option be enabled in
/var/lib/buttervolume/ssh/config on local host.
Please note you have to restart you docker daemons each time you change ssh configuration.
The default SSH_PORT of the ssh server included in the plugin is 1122. You can
change it with docker plugin set anybox/buttervolume SSH_PORT=<PORT> before
enabling the plugin.


Synchronize a volume from another host volume
You can receive data from a remote volume, so in case there is a volume on
the remote host with the same name, it will get new and most recent data
from the distant volume and replace in the local volume. Before running the
rsync command a snapshot is made on the local machine to manage recovery:
buttervolume sync <volume> <host1> [<host2>][...]
The intent is to synchronize a volume between multi hosts on running
containers, so you should schedule that action on each nodes from all remote
hosts.

Note
As we are pulling data from multiple hosts we never remove data, consider
removing scheduled actions before removing data on each hosts.


Warning
Make sure your application is able to handle such synchronisation



Purge old snapshots
You can purge old snapshot corresponding to the specified volume, using a retention pattern:
buttervolume purge <pattern> <volume>
If you’re unsure whether you retention pattern is correct, you can run the
purge with the --dryrun option, to inspect what snapshots would be deleted,
without deleting them:
buttervolume purge --dryrun <pattern> <volume>
<volume> is the name of the volume, not the full path. It is expected
to live in /var/lib/buttervolume/volumes.
<pattern> is the snapshot retention pattern. It is a semicolon-separated
list of time length specifiers with a unit. Units can be m for minutes,
h for hours, d for days, w for weeks, y for years. The pattern
should have at least 2 items.
Here are a few examples of retention patterns:


4h:1d:2w:2y
Keep all snapshots in the last four hours, then keep only one snapshot
every four hours during the first day, then one snapshot per day during
the first two weeks, then one snapshot every two weeks during the first
two years, then delete everything after two years.




4h:1w
keep all snapshots during the last four hours, then one snapshot every
four hours during the first week, then delete older snapshots.




2h:2h
keep all snapshots during the last two hours, then delete older snapshots.






Schedule a job
You can schedule a periodic job, such as a snapshot, a replication, a
synchronization or a purge. The schedule it self is stored in
/etc/buttervolume/schedule.csv.
Schedule a snapshot of a volume every 60 minutes:
buttervolume schedule snapshot 60 <volume>
Remove the same schedule by specifying a timer of 0 min:
buttervolume schedule snapshot 0 <volume>
Schedule a replication of volume foovolume to remote_host:
buttervolume schedule replicate:remote_host 3600 foovolume
Remove the same schedule:
buttervolume schedule replicate:remote_host 0 foovolume
Schedule a purge every hour of the snapshots of volume foovolume, but
keep all the snapshots in the last 4 hours, then only one snapshot every 4
hours during the first week, then one snapshot every week during one year, then
delete all snapshots after one year:
buttervolume schedule purge:4h:1w:1y 60 foovolume
Remove the same schedule:
buttervolume schedule purge:4h:1w:1y 0 foovolume
Using the right combination of snapshot schedule timer, purge schedule timer
and purge retention pattern, you can create you own backup strategy, from the
simplest ones to more elaborate ones. A common one is the following:
buttervolume schedule snapshot 1440 <volume>
buttervolume schedule purge:1d:4w:1y 1440 <volume>
It should create a snapshot every day, then purge snapshots everydays while
keeping all snapshots in the last 24h, then one snapshot per day during one
month, then one snapshot per month during only one year.
Schedule a syncrhonization of volume foovolume from remote_host1
abd remote_host2:
buttervolume schedule synchronize:remote_host1,remote_host2 60 foovolume
Remove the same schedule:
buttervolume schedule synchronize:remote_host1,remote_host2 0 foovolume


List scheduled jobs
You can list all the scheduled job with:
buttervolume scheduled
It will display the schedule in the same format used for adding the schedule,
which is convenient to remove an existing schedule or add a similar one.


Copy-on-write
Copy-On-Write is enabled by default. You can disable it if you really want.
Why disabling copy-on-write? If your docker volume stores databases such as
PostgreSQL or MariaDB, the copy-on-write feature may hurt performance, though
the latest kernels have improved a lot. The good news is that disabling
copy-on-write does not prevent from doing snaphots.



Testing
If your volumes directory is a BTRFS partition or volume, tests can be run
with:
./test.sh


Working without a BTRFS partition
If you have no BTRFS partitions or volumes you can setup a virtual partition
in a file as follows (tested on Debian 8):
Setup BTRFS virtual partition:
sudo qemu-img create /var/lib/docker/btrfs.img 10G
sudo mkfs.btrfs /var/lib/docker/btrfs.img

Note
you can ignore the error, in fact the new FS is formatted

Mount the partition somewhere temporarily to create 3 new BTRFS subvolumes:
sudo -s
mkdir /tmp/btrfs_mount_point
mount -o loop /var/lib/docker/btrfs.img /tmp/btrfs_mount_point/
btrfs subvolume create /tmp/btrfs_mount_point/snapshots
btrfs subvolume create /tmp/btrfs_mount_point/volumes
btrfs subvolume create /tmp/btrfs_mount_point/received
umount /tmp/btrfs_mount_point/
rm -r /tmp/btrfs_mount_point/
Stop docker, create required mount point and restart docker:
systemctl stop docker
mkdir -p /var/lib/buttervolume/volumes
mkdir -p /var/lib/buttervolume/snapshots
mkdir -p /var/lib/buttervolume/received
mount -o loop,subvol=volumes /var/lib/docker/btrfs.img /var/lib/buttervolume/volumes
mount -o loop,subvol=snapshots /var/lib/docker/btrfs.img /var/lib/buttervolume/snapshots
mount -o loop,subvol=received /var/lib/docker/btrfs.img /var/lib/buttervolume/received
systemctl start docker
Once you are done with your test, you can unmount those volumes and you will
find back your previous docker volumes:
systemctl stop docker
umount /var/lib/buttervolume/volumes
umount /var/lib/buttervolume/snapshots
umount /var/lib/buttervolume/received
systemctl start docker
rm /var/lib/docker/btrfs.img


Migrate to version 3
If you’re currently using Buttervolume 1.x or 2.0 in production, you must
carefully follow the guidelines below to migrate to version 3.
First copy the ssh and config files and disable the scheduler:
sudo -s
docker cp buttervolume_plugin_1:/etc/buttervolume /var/lib/buttervolume/config
docker cp buttervolume_plugin_1:/root/.ssh /var/lib/buttervolume/ssh
mv /var/lib/buttervolume/config/schedule.csv /var/lib/buttervolume/config/schedule.csv.disabled
Then stop all your containers, excepted buttervolume
Now snapshot and delete all your volumes:
volumes=$(docker volume ls -f driver=btrfs --format "{{.Name}}")
# or: # volumes=$(docker volume ls -f driver=btrfs|tail -n+2|awk '{print $2}')
echo $volumes
for v in $volumes; do docker exec buttervolume_plugin_1 buttervolume snapshot $v; done
for v in $volumes; do docker volume rm $v; done
Then stop the buttervolume container, remove the old btrfs.sock file, and
restart docker:
docker stop buttervolume_plugin_1
docker rm -v buttervolume_plugin_1
rm /run/docker/plugins/btrfs.sock
systemctl stop docker
If you were using Buttervolume 1.x, you must move your snapshots to the new location:
mkdir /var/lib/buttervolume/snapshots
cd /var/lib/docker/snapshots
for i in *; do btrfs subvolume snapshot -r $i /var/lib/buttervolume/snapshots/$i; done
Restore /var/lib/docker/volumes as the original folder:
cd /var/lib/docker
mkdir volumes.new
mv volumes/* volumes.new/
umount volumes # if this was a mounted btrfs subvolume
mv volumes.new/* volumes/
rmdir volumes.new
systemctl start docker
Change your volume configurations (in your compose files) to use the new
anybox/buttervolume:latest driver name instead of btrfs
Then start the new buttervolume 3.x as a managed plugin and check it is started:
docker plugin install anybox/buttervolume:latest
docker plugin ls
Then recreate all your volumes with the new driver and restore them from the snapshots:
for v in $volumes; do docker volume create -d anybox/buttervolume:latest $v; done
export RUNCROOT=/run/docker/runtime-runc/plugins.moby/ # or /run/docker/plugins/runtime-root/plugins.moby/
alias drunc="sudo runc --root $RUNCROOT"
alias buttervolume="drunc exec -t $(drunc list|tail -n+2|awk '{print $1}') buttervolume"
# WARNING : check the the volume you will restore are the correct ones
for v in $volumes; do buttervolume restore $v; done
Then restart your containers, check they are ok with the correct data.
Reenable the schedule:
mv /var/lib/buttervolume/config/schedule.csv.disabled /var/lib/buttervolume/config/schedule.csv


Credits
Thanks to:

Christophe Combelles
Pierre Verkest
Marcelo Ochoa
Christoph Rist
Philip Nagler-Frank
Yoann MOUGNIBAS




CHANGELOG

3.10 (2023-04-09)

updated dependencies
fixed bug #45



3.9 (2022-10-11)

Fixed a crash when option_copyonwrite is not set
Restored the test suite
Improved and simplified the build script and test script



3.8 (2022-10-07)

Switched to copy-on-write by default
Allow to choose to enable/disable copy-on-write for each volume
Allow to change the default SSH_PORT in the plugin config
Updated the base docker image and dependencies
Added an option to show the version number
Improved documentation



3.7 (2018-12-13)

Unpinned urllib3



3.6 (2018-12-11)

Fixed zombie sshd processes inside the plugin
Minor documentation change



3.5 (2018-06-07)

Improved documentation



3.4 (2018-04-27)

Fix rights at startup so that ssh works



3.3 (2018-04-27)

Fixed a bug preventing a start in certain conditions



3.2 (2018-04-27)

Fixed the socket path for startup



3.1 (2018-04-27)

Fixed a declaration in Python 3.6
Automatically detects the btrfs.sock path
Made the runpath and drivername configurable



3.0 (2018-04-24)

Now use the docker managed plugin system
Stop the scheduler before shutdown to avoid a 5s timeout
Improved logging
Improved the migration doc from version 1 or 2



2.0 (2018-03-24)


BREAKING CHANGE: Please read the migration path from version 1 to version 2:
BTRFS volumes and snapshots are now stored by default in different directories under /var/lib/buttervolume



Configuration possible through environment variables or a config.ini file
implemented VolumeDriver.Capabilities and just return 'local'
other minor fixes and improvements



1.4 (2018-02-01)

Add clone command
replace sync by btrfs filesystem sync



1.3.1 (2017-10-22)

fixed packaging (missing README)



1.3 (2017-07-30)

fixed the cli for the restore command



1.2 (2017-07-16)

fixed the purge algorithm



1.1 (2017-07-13)

allow to restore a snapshot to a different volume name



1.0 (2017-05-24)

initial release, used in production