Docker volume plugin

[Vaibhav Khanduja]

Hi 

I am trying to use external volumes using new docker volume plugin. I see during mount call the plugin expects a local mount point or path to given back as response. My storage is external for some reasons, I cannot mount the drive locally. Is there a way where I can call in hook, which is invoked from within container? I read blogs which suggest entrypoint, but I realize mount is called during container start and entrypoint is called after start is complete.

Thx

[Brian Goff]

The plugin should be able to handle this mount, otherwise it's not much good as a plugin.

Even if the storage is remote, the idea here is you have a plugin that is either 1) an agent running on the host itself, or 2) Somehow has remote access to the host to perform the required operations.

[Luca Cipriani]

Hello,

You can probably try using nsenter that avoids some limitations: https://github.com/jpetazzo/nsenter

[Shripad Nadgowda]

Is there any documentation available on how to develop a new volume plugin? I am also interested in building a network attached storage backend for volumes. But, couldn;t find the right documentation,

Thanks

[Vaibhav Khanduja]

This is a good starting point 

https://github.com/calavera/dkvolume

Sent from my iPhone. Please excuse the typos and brevity of this message.

[Shripad Nadgowda]

Thanks.

I am trying from it. But, i keep getting docker deamon error:

Error response from daemon: Error looking up volume plugin myX: Plugin not found

How do i register my plugin with docker? I thought, docker would simply forward the requests to <driver>.sock

[Vaibhav Khanduja]

The plugins are supported with docker version which is in experimental. Search for getting latest experimental docker version, you should be able to make it work. 

Sent from my iPhone. Please excuse the typos and brevity of this message.

[Shripad Nadgowda]

Yes, I am trying with experimental version 1.8.0-dev. But, not working with it:(

[Vaibhav Khanduja]

Okay .. There is no registration step but the docker daemon looks for the plugin name Unix socket file under plugin dir of docker install. Can you throw more details? The plugin name.. socket file name etc 

Look more info on this vdo: https://youtu.be/SVtsT9WVujs

Sent from my iPhone. Please excuse the typos and brevity of this message.

[Shripad Nadgowda]

I build my docker plugin  named docker-volume-myfs and i started it to listen on myfs.sock.

# ./docker-volume-myfs
listening on /usr/share/docker/plugins/

myfs.sock


Then i tried to make a  'docker run' as follows:

# ./docker-latest --version
Docker version 1.8.0-dev, build 5fdc102, experimental

# ./docker-latest run --volume-driver myfs --volume /data mysql:5.6.17
Error response from daemon: Error looking up volume plugin myfs: Plugin not found

When i looked up this error in docker code, it seems to be coming from
https://github.com/docker/docker/blob/master/volume/drivers/extpoint.go#L61

Here, the Lookup() call seem to be failing. Any idea?

Thanks

On Friday, July 10, 2015 at 1:53:06 AM UTC+5:30, Vaibhav Khanduja wrote:

[srust.bl...@gmail.com]

The directory for plugins to listen on the unix socket has changed in the official 1.8 release.

It is in /run/docker/plugins.

See: https://docs.docker.com/extend/plugin_api/

For the full documentation.

[Rajagopal Vaideeswaran]

All,

Recently we launched Storage Support for Docker Containers with a plugin. The [link] has the details to join the community and try the plugin for free.

Do pass on your valuable feedback via the community.You are most welcome.

with regards,

Rajagopal