Docker Volume Driver For Linode

This volume plugin adds the ability to manage Linode Block Storage as Docker Volumes from within a Linode. Good use cases for volumes include off-node storage to avoid size constraints or moving a container and the related volume between nodes in a Swarm.

Requirements

• Linux (tested on Fedora 34, should work with other versions and distributions)
• Docker (tested on version 20, should work with other versions)

Installation

docker plugin install --alias linode --grant-all-permissions \
linode/docker-volume-linode \
linode-token=<linode token>

Driver Options

Option Name	Description
linode-token	Required The Linode APIv4 Personal Access Token to use. (requires linodes:read_write volumes:read_write events:read_only)
linode-label	The label of the current Linode. This is only necessary if your Linode does not have a resolvable Link Local IPv6 Address.
force-attach	If true, volumes will be forcibly attached to the current Linode if already attached to another Linode. (defaults to false) WARNING: Forcibly reattaching volumes can result in data loss if a volume is not properly unmounted.
mount-root	Sets the root directory for volume mounts (defaults to /mnt)
log-level	Sets log level to debug,info,warn,error (defaults to info)
socket-user	Sets the user to create the docker socket with (defaults to root)

Options can be set once for all future uses with docker plugin set.

Changing the plugin configuration

The plugin can also be configured (or reconfigured) in multiple steps.

docker plugin install --alias linode linode/docker-volume-linode
docker plugin disable linode
docker plugin set linode linode-token=<linode token>
docker plugin enable linode

• For all options see Driver Options section

Docker Swarm

Volumes can be mounted to one container at the time because Linux Block Storage volumes can only be attached to one Linode at the time.

Usage

All examples assume the driver has been aliased to linode.

Create Volume

Linode Block Storage volumes can be created and managed using the docker volume create command.

$ docker volume create -d linode my-test-volume
my-test-volume

If a named volume already exists on the Linode account and it is in the same region of the Linode, it will be reattached if possible. A Linode Volume can be attached to a single Linode at a time.

Create Options

The driver offers driver specific volume create options:

Option	Type	Default	Description
size	int	10	the size (in GB) of the volume to be created. Volumes must be at least 10GB in size, so the default is 10GB.
filesystem	string	ext4	the filesystem argument for mkfs when formating the new (raw) volume (xfs, btrfs, ext4)
delete-on-remove	bool	false	if the Linode volume should be deleted when removed

$ docker volume create -o size=50 -d linode my-test-volume-50
my-test-volume-50

Volumes can also be created and attached from docker run:

docker run -it --rm --mount volume-driver=linode,source=test-vol,destination=/test,volume-opt=size=25 alpine

Multiple create options can be supplied:

docker run -it --rm --mount volume-driver=linode,source=test-vol,destination=/test,volume-opt=size=25,volume-opt=filesystem=btrfs,volume-opt=delete-on-remove=true alpine

List Volumes

$ docker volume ls
DRIVER              VOLUME NAME
linode:latest       my-test-volume
linode:latest       my-test-volume-50

Use Volume

$ docker run --rm -it -v my-test-volume:/usr/local/apache2/htdocs/ httpd
...

Remove Volumes

$ docker volume rm my-test-volume
my-test-volume

$ docker volume rm my-test-volume-50
my-test-volume-50

Manual Installation

• Install Golang: https://golang.org/
• Get code and Compile: go get -u github.com/linode/docker-volume-linode

Run the driver

docker-volume-linode --linode-token=<token from linode console>

Debugging

Enable Debug Level on plugin

The driver name when running manually is the same name as the socket file.

docker plugin set docker-volume-linode log-level=debug

Enable Debug Level in manual installation

docker-volume-linode --linode-token=<...> --log-level=debug

Development

A great place to get started is the Docker Engine managed plugin system documentation.

Running Integration Tests

The integration tests for this project can be easily run using the make int-test target. This target provisions and connects to a Linode instance, uploads the plugin, builds it, enables it, and runs the integration test suite. Subsequent runs of this target will re-use the existing Linode instance.

In order to run this target, Ansible and the Linode Ansible Collection must be installed on the local machine:

pip install ansible

ansible-galaxy collection install linode.cloud

pip install -r https://raw.githubusercontent.com/linode/ansible_linode/main/requirements.txt

The integration test suite also requires that a full-access Linode Personal Access Token be exported as the LINODE_TOKEN environment variable.

export LINODE_TOKEN=EXAMPLETOKEN

The integration test suite can now be run:

make int-test

NOTE: This target requires an existing SSH key be created. If an SSH key exists at a path other than ~/.ssh/id_rsa, the QUICKTEST_SSH_PUBKEY argument can be specified:

make QUICKTEST_SSH_PUBKEY="~/.ssh/mykey.pub" int-test

If you would like to create a test environment for docker-volume-linode without running the integration test suite, the QUICKTEST_SKIP_TESTS argument can be specified:

make QUICKTEST_SKIP_TESTS=1 int-test

Discussion / Help

Join us at #linodego on the gophers slack