Fix bind-volumes on docker >= 1.4.0

[steveej]

If bind-volumes are submitted to docker >= 1.4.0 with the volumes set in addition to the binds, docker will create a regular volume and not bind-mount the specified path.

[lorin]

I tried out this patch locally since I needed the functionality, and I hit a case where this fix didn't work.

If the image specifies a volume directory, and you try to bind a local directory to the volume directory, Docker won't bind the container directory to the host directory.

For example, the Dockerfile of the official nginx image contains:

VOLUME ["/var/cache/nginx"]

If you try to bind this directory to a local directory using the docker module, Docker still won't do the bind correctly:

- docker:
    image: nginx
    name: mynginx
    volumes: /home/lorin/nginx-cache:/var/cache/nginx

I worked around it by passing the bind info in the host_config parameter that gets passed to the create_container method.

diff --git a/cloud/docker/docker.py b/cloud/docker/docker.py
index f71bad4..4c74b1c 100644
--- a/cloud/docker/docker.py
+++ b/cloud/docker/docker.py
@@ -721,6 +721,7 @@ class DockerManager(object):
                   'volumes':      self.volumes,
                   'mem_limit':    _human_to_bytes(self.module.params.get('memory_limit')),
                   'environment':  self.env,
+                  'host_config':  docker.utils.create_host_config(binds=self.binds),
                   'hostname':     self.module.params.get('hostname'),
                   'detach':       self.module.params.get('detach'),
                   'name':         self.module.params.get('name'),

This seems to be discussed in docker/docker-py#419 as bug in docker-py.

[steveej]

I've updated my PR with additional changes.

Things I've tested successfully with the official nginx image

running the image without additional binds

$ ansible -i 'localhost,' localhost -m docker -a 'image=nginx state=running'

                "Volumes": {
                    "/var/cache/nginx": "/var/lib/docker/vfs/dir/4442d05a9d1b51eb82bb27f293809d60c0ad5eecfbe047f7e28db91c45e36c84"
                },
                "VolumesRW": {
                    "/var/cache/nginx": true
                }

running the image and overriding the VOLUME from the Dockerfile

$ ansible -i 'localhost,' localhost -m docker -a 'image=nginx state=running volumes=/var/tmp/nginx-cache:/var/cache/nginx'

                "Volumes": {
                    "/var/cache/nginx": "/var/tmp/nginx-cache"
                },
                "VolumesRW": {
                    "/var/cache/nginx": true
                }

$ ls -l /var/tmp/nginx-cache/

total 0
drwx------ 1 messagebus root 0 12. Mär 13:27 client_temp
drwx------ 1 messagebus root 0 12. Mär 13:27 fastcgi_temp
drwx------ 1 messagebus root 0 12. Mär 13:27 proxy_temp
drwx------ 1 messagebus root 0 12. Mär 13:27 scgi_temp
drwx------ 1 messagebus root 0 12. Mär 13:27 uwsgi_temp

This looks like correct behavior to me.

@lorin
Could you please verify that the problem is gone with my latest commits?

[lorin]

@steveej Just tested it out, this commit resolves the issue. 👍

[magicrobotmonkey]

This would be really nice to see fixed,makes it difficult to use ansible to orchestrate containers

[stefanvanwouw]

Have the same problem. Please accept this PR. +1

[maliskovik]

same issue here.

[lchorbadjiev]

+1

[gregdek]

Lots of love for this PR, including a +1 from @lorin -- promoting to P1_reviewed.