Image Inspector can extract docker images to a target directory and (optionally) serve the content through webdav.
$ ./image-inspector --image=fedora:22 --serve 0.0.0.0:8080
2015/12/10 19:24:44 Image fedora:22 is available, skipping image pull
2015/12/10 19:24:44 Extracting image fedora:22 to
/var/tmp/image-inspector-121627917
2015/12/10 19:24:46 Serving image content
/var/tmp/image-inspector-121627917 on
webdav://0.0.0.0:8080/api/v1/content/
$ cadaver http://localhost:8080/api/v1/content
dav:/api/v1/content/> ls
Listing collection `/api/v1/content/': succeeded.
Coll: boot 4096 Dec 10 20:24
Coll: dev 4096 Dec 10 20:24
Coll: etc 4096 Dec 10 20:24
Coll: home 4096 Dec 10 20:24
Coll: lost+found 4096 Dec 10 20:24
...
To build image-inspector using godep:
$ godep go build
$ docker run -ti --rm --privileged \
-v /var/run/docker.sock:/var/run/docker.sock \
openshift/image-inspector --image=fedora:20 --path=/tmp/image-content