CMDFS in docker

WARNING: This instruction is not ready yet! We are waiting for some fixes in cmdfs project! (2017 Sep 25)

This is a docker container using cmdfs fuse file system.

Usage examples:

You have a folder structure containing ALL your photos. You would like to see your photos on your digital photo frame (maybe an old tablet), but you don't like to scale and copy newly added fotos time and again to the frames storage. Additionally you dont want to show ALL of your Photos. Some private subfolder should be excluded. Here comes cmdfs. Some possibilities:

• present a filtered subset of you photo collections in a dynamically populated folder. This folder can be share then through samba or dlna/upnp to your photo frame
• present only landscape oriented photos out of your full collection to the photo frame
• run automatic rsync backups of downscaled versions of your photos
• many more

How to use

Download and extract all these files to a folder on your host.

Or use git to download

git clone https://github.com/allofmex/docker-cmdfs.git

Before we can use cmdfs we need to compile it from source. We will do this in a temporary gcc container to keep the host clean:

sudo su
cd /HOSTPATHOFCMDFSFILES
chmod u+x build.sh
chmod a+x config-example/*.sh
./build.sh

This should download, init and run the build process. If all went fine, you will have a cmdfs-latest.deb file in the work folder.

Prepare mount points where your filtered folder should appear:

mkdir /HOSTFILTEREDFOTOSDIR
chmod a+w /HOSTFILTEREDFOTOSDIR

Now we have cmdfs ready to be installed in a container:

Build image and run container

Docker

docker build -t cmdfs-image .
docker run -d -v /HOSTFOTODIR:/hostSource:ro -v /HOSTFILTEREDFOTOSDIR:/hostTarget:shared --privileged cmdfs-image

Or if you prefer docker-compose

Edit docker-compose.yml based on your environment first. Then:

docker-compose build
docker-compose up -d

In this case the container will use the example configuration in folder config-example. It's configured to:

• mount a folder photos_all in your HOSTFILTEREDFOTOSDIR, containing a downscaled version of all jpg,png,... files
• a second folder photos_landscape which uses the first photos_all as input but presents only photos that have landscape aspect ratio (wider than high)

The mounts are getting exposed to host system. This approach enables it to use the resulting folder e.g. for a second samba container. (see "Extra notes" below)

Customization

If not specified, the container will use config in config-example. You may want to use your own filter settings. Just copy folder config-example to /HOSTPATHOFCMDFSFILES/config and add

-v /HOSTPATHOFCMDFSFILES/config:/etc/cmdfs/

in docker run command or uncomment the correspondending line in docker-compose.yml if you use compose. The container will call run.sh script at initialization. If you like to setup own mount, add or edit cmdfs /hostSource /hostTarget/... lines. How to configure the -o "..." options see http://cmdfs.sourceforge.net/ or http://www.linux-magazine.com/Online/Features/Cmdfs

Extra notes:

• We need --privileged setting to be able to mount within container
• This container is configured to expose the mounts back to host to use them again in other container or on host itself. To achieve this we have :shared at the volume mount. Without it would be visible only inside the container.
• You need allow_other option in cmdfs (fuse) mount option. There may be better (more secure) options, but than you have to handle user/group settings if you want to access the mount from other container.
• If you use the cmdfs created folder as container volume mount for another container (-v .../photos_all:/mnt...), make sure the cmdfs container gets started before you start the second container or mount parent folder of cmdfs mountpoint. Else the mount don't gets visible in the container!
• You may add -v /CMDFSCACHE:/c to keep the cmdfs cache persistent (maybe your photos source is a harddisk, running only on access and you like to put the cache on a ssd. Repeated access to same file will not cause your harddisk to spin-up.)

Debugging:

To see if container is STATUS UP and to get container name:

docker ps

For more info about startup:

docker logs CONTAINERNAME

You may also add /dev/log:/dev/log to your container volume mounts to receive cmdfs syslog messages on host.