Metadata-Version: 1.1
Name: buttervolume
Version: 1.3
Summary: Docker plugin to manage Docker Volumes as BTRFS subvolumes
Home-page: https://github.com/anybox/buttervolume
Author: Christophe Combelles
Author-email: ccomb@anybox.fr
License: Apache License, Version 2.0
Description: .. image:: https://travis-ci.org/anybox/buttervolume.svg?branch=master
           :target: https://travis-ci.org/anybox/buttervolume
           :alt: Travis state
        
        
        BTRFS Volume plugin for Docker
        ==============================
        
        This package provides a Docker volume plugin that creates a BTRFS subvolume for
        each container volume.
        
        Please note this is **not** a BTRFS storage driver for Docker, but a plugin to manage only
        volumes. It means you can use any storage driver, such as AUFS, this is independant topic.
        
        .. contents::
        
        Introduction
        ************
        
        `BTRFS <https://btrfs.wiki.kernel.org/>`_ is a next-generation copy-on-write
        filesystem with subvolume and snapshot support. A BTRFS `subvolume
        <https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Subvolumes>`_ 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
        <https://docs.docker.com/engine/tutorials/dockervolumes/>`_ 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 a
        dumb directory in the host filesystem.  A number of `Volume plugins
        <https://docs.docker.com/engine/extend/legacy_plugins/#/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.
        
        Build
        *****
        
        You can build a docker image with the provided Dockerfile::
        
            $ cd docker
            $ docker build -t buttervolume .
        
        Install and run
        ***************
        
        Make sure the directory ``/var/lib/docker/volumes`` is living in a BTRFS
        filesystem. It can be a BTRFS mountpoint or a BTRFS subvolume or both.
        You should also create the directory for the unix socket of the plugin::
        
            $ sudo mkdir /run/docker/plugins
        
        Then create a container for buttervolume with access to the host volumes and
        the unix socket
        
        Either from the image you just built::
        
            $ sudo docker create --privileged -v /var/lib/docker:/var/lib/docker -v /run/docker/plugins/:/run/docker/plugins/ --name buttervolume buttervolume
            $ docker start buttervolume
        
        Or directly by pulling a `prebaked image <https://hub.docker.com/r/anybox/buttervolume/>`_ from the Docker hub::
        
            $ docker run --privileged -v /var/lib/docker/volumes:/var/lib/docker/volumes -v /run/docker/plugins:/run/docker/plugins anybox/buttervolume
        
        You can also locally install and run the plugin with::
        
            $ virtualenv venv
            $ ./venv/bin/python setup.py develop
            $ sudo ./venv/bin/buttervolume run
        
        Usage
        *****
        
        Running the plugin
        ------------------
        
        If you installed it locally, You can start the plugin with::
        
            $ sudo buttervolume run
        
        If you're running it in a privileged container, it will be automatically started.
        
        When started it will create a unix socket ``/var/run/docker/plugins/btrfs.sock`` for use by
        Docker. The name of the socket file is actually the name of the plugin you can
        use with ``docker volume create -d <driver>`` or ``docker create --volume-driver=<driver>``.  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)
            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/docker/volumes`` and
        the snapshot will be created in ``/var/lib/docker/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/docker/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/docker/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>
        
        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/docker/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/docker/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. This requires that ssh
        keys be present and already authorized on the target host, and that the
        ``StrictHostKeyChecking no`` option be enabled in ``~/.ssh/config``.
        
        
        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 distantant volume and replace in the local volume. Before running the
        ``rsync`` command a snapshot is made on the locale 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/docker/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.
        
        Disabling copy-on-write
        -----------------------
        
        UPDATE: Copy On Write is disabled by default.
        
        TODO: replace the .nocow file feature with an option to pass
        
        With `buttervolume` you can disable copy-on-write in a volume by creating a ``.nocow`` file at the
        root of the volume. The `buttervolume` plugin will detect it at mount-time and apply ``chattr +C`` on the volume root.
        
        Why disabling copy-on-write? If your docker volume stores databases such as
        PostgreSQL or MariaDB, the copy-on-write feature may hurt performance a lot.
        The good news is that disabling copy-on-write does not prevent from doing
        snaphots, so we get the best of both world: good performances with the ability
        to do snapshots.
        
        Creating such a ``.nocow`` file can easily be done in a Dockerfile, before the
        ``VOLUME`` command:
        
        .. code:: Dockerfile
        
            RUN mkdir -p /var/lib/postgresql/data \
                && chown -R postgres: /var/lib/postgresql/data \
                && touch /var/lib/postgresql/data/.nocow
            VOLUME /var/lib/postgresql/data
        
        Alternatively you can create the ``.nocow`` file just after the ``docker
        create`` command, by inspecting the location of the created volumes with
        ``docker inspect container | grep volumes``.
        
        Test
        ****
        
        If your volumes directory is a BTRFS partition or volume, tests can be run
        with::
        
            $ export SSH_PORT=22  # port of your running ssh server with authorized key
            $ sudo -E python3 setup.py test
        
        or using and testing the docker image (with python >= 3.5)::
        
            $ docker build -t anybox/buttervolume docker/
            $ sudo docker run -it --rm --privileged \
                -v /var/lib/docker:/var/lib/docker \
                -v "$PWD":/usr/src/buttervolume \
                -w /usr/src/buttervolume \
                anybox/buttervolume test
        
        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
            Formatting '/var/lib/docker/btrfs.img', fmt=raw size=10737418240
            $ sudo mkfs.btrfs /var/lib/docker/btrfs.img
            Btrfs v3.17
            See http://btrfs.wiki.kernel.org for more information.
        
            Turning ON incompat feature 'extref': increased hardlink limit per file to 65536
            ERROR: device scan failed '/var/lib/docker/btrfs.img' - Block device required
            fs created label (null) on /var/lib/docker/btrfs.img
                nodesize 16384 leafsize 16384 sectorsize 4096 size 10.00GiB
        
        .. 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 mkdir /tmp/btrfs_mount_point \
                && sudo mount -o loop /var/lib/docker/btrfs.img /tmp/btrfs_mount_point/ \
                && sudo btrfs subvolume create /tmp/btrfs_mount_point/snapshots \
                && sudo btrfs subvolume create /tmp/btrfs_mount_point/volumes \
                && sudo btrfs subvolume create /tmp/btrfs_mount_point/received \
                && sudo umount /tmp/btrfs_mount_point/ \
                && sudo rm -r /tmp/btrfs_mount_point/
        
        * Stop docker, create required mount point and restart docker::
        
            $ sudo systemctl stop docker \
                && sudo mkdir -p /var/lib/docker/volumes \
                && sudo mkdir -p /var/lib/docker/snapshots \
                && sudo mkdir -p /var/lib/docker/received \
                && sudo mount -o loop,subvol=volumes /var/lib/docker/btrfs.img /var/lib/docker/volumes \
                && sudo mount -o loop,subvol=snapshots /var/lib/docker/btrfs.img /var/lib/docker/snapshots \
                && sudo mount -o loop,subvol=received /var/lib/docker/btrfs.img /var/lib/docker/received \
                && sudo systemctl start docker
        
        * once you are done with your test when you can umount those volume and you will
          find back your previous docker volumes::
        
        
            $ sudo systemctl stop docker \
                && sudo umount /var/lib/docker/volumes \
                && sudo umount /var/lib/docker/snapshots \
                && sudo umount /var/lib/docker/received \
                && sudo systemctl start docker \
                && sudo rm /var/lib/docker/btrfs.img
        
        Credits
        *******
        
        - Christophe Combelles
        - Pierre Verkest
        
        
        CHANGELOG
        =========
        
        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
        
        
Platform: UNKNOWN
Classifier: Programming Language :: Python :: 3
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: System Administrators
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Operating System :: POSIX :: Linux
Classifier: Topic :: System :: Clustering
