Can't mount HOST folder into Amazon Docker Container?

Question

I'm using an EC2 instance to run docker. From my local machine using OSX, I'm using docker machine to create containers and volumes. However when I'm trying to mount a local folder to any container is not possible.

docker create -v /data --name data-only-container ubuntu /bin/true
docker run -it --volumes-from data-only-container -v $(pwd)/data:/backup ubuntu bash

With the first command I create a data only container and I'm executing the second command to get into a container that should have the data-only-container volumes and the one I'm trying to mount, however when access it the folder /backup is empty

What I'm doing wrong?

EDIT: I'm trying to mount a host folder in order to restore backuped data from my PC to container. In that case what would be a different approach?

Shall I try to use Flocker?

Answer 1

A host volume mounted with -v /path/to/dir:/container/mnt mounts a directory from the docker host inside the container. When you run this command on your OSX system, the $(pwd)/data will reference a directory on your local machine that doesn't exist on the docker host, the EC2 instance. If you log into your EC2 instance, you'll likely find the $(pwd)/data directory created there and empty.

If you want to mount folders from your OSX system into a docker container, you'll need to run Docker on the OSX system itself.

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Edit: To answer the added question of how to move data up to your container in the cloud, there are often ways to move your data to the cloud provider itself, outside of docker, and then include it directly inside the container. To do a docker only approach, you can do something like:

tar -cC /source . | \
docker run --rm -i -v app-data:/target busybox \
  /bin/sh -c "tar -xC /target"

This will upload your data with tar over a pipe into a named volume on your docker host. You can then include the named "app-data" volume in any other containers. If you need to do this multiple times with larger data sets, creating an rsync container would be more efficient.