Dockerised WebDAV Client

This Docker image (also at the GHCR) and associated project facilitate mounting of remote WebDAV resources into containers. Mounting is implemented using davfs2 and the image makes it possible to set all supported davfs configuration options for the share. The image basically implements a docker volume on the cheap: Used with the proper creation options (see below) , you should be able to bind-mount back the remote bucket onto a host directory. This directory will make the content of the bucket available to processes, but also all other containers on the host. The image automatically unmounts the remote bucket on container termination.

Example

Provided the existence of a directory called /mnt/tmp on the host, the following command would mount a remote WebDAV resource, ensure that authentication details are never requested from the command-line and bind-mount the remote resource onto the host's /mnt/tmp in a way that makes the remote files accessible to processes and/or other containers running on the same host.

docker run -it --rm \
    --device /dev/fuse \
    --cap-add SYS_ADMIN \
    --security-opt "apparmor=unconfined" \
    --env "WEBDRIVE_USERNAME=<YourUserName>" \
    --env "WEBDRIVE_PASSWORD=<SuperSecretPassword>" \
    --env "WEBDRIVE_URL=https://dav.box.com/dav" \
    --env "DAVFS2_ASK_AUTH=0" \
    -v /mnt/tmp:/mnt/webdrive:rshared \
    efrecon/webdav-client

The --device, --cap-add and --security-opt options and their values are to make sure that the container will be able to make available the WebDAV resource using FUSE. rshared is what ensures that bind mounting makes the files and directories available back to the host and recursively to other containers.

Container Options

A series of environment variables, most led by WEBDRIVE_ can be used to parametrise the container:

• WEBDRIVE_URL is the URL at which to find the WebDAV resource.
• WEBDRIVE_USERNAME is the user to use for accessing the resource.
• WEBDRIVE_PASSWORD is the password for that user.
• WEBDRIVE_PASSWORD_FILE points instead to a file that will contain the password for the user. When this is present, the password will be taken from the file instead of from the WEBDRIVE_PASSWORD variable. If that variable existed, it will be disregarded. This makes it easy to pass passwords using Docker secrets.
• WEBDRIVE_MOUNT is the location within the container where to mount the WebDAV resource. This defaults to /mnt/webdrive and is not really meant to be changed.
• OWNER is the user ID for the owner of the share inside the container.

davFS Options

All configuration options recognised by davFS can be given for that particular share. Environment variables should be created out of the name of the configuration option for this to work. Any existing option should be translated to uppercase and led by the keyword DAVFS2_ to be recognised. So to set the davfs2 option called ask_auth to 0, you would set the environment variable DAVFS2_ASK_AUTH to 0.

Commands

By default, containers based on this image will keep listing the content of the mounted directory at regular intervals. This is implemented by the command that it is designed to execute once the remote WebDAV resource has been mounted. If you did not wish this behaviour, pass empty.sh as the command instead.

Note that both of these commands ensure that the remote WebDAV resource is unmounted from the mountpoint at termination, so you should really pick one or the other to allow for proper operation. If the mountpoint was not unmounted, your mount system will be unstable as it will contain an unknown entry.

Automatic unmounting is achieved through a combination of a trap in the command being executed and tini. tini is made available directly in this image to make it possible to run in Swarm environments.