Pull missing images on run. Addresses #31.

[chooper]

Pull missing images on run. Addresses #31.

chooper@chimay:~/projects/docker/bin$ ./docker images
NAME                ID                  CREATED             PARENT
chooper@chimay:~/projects/docker/bin$ ./docker run -a base echo "hello world"
Downloading from http://s3.amazonaws.com/docker.io/images/base
Unpacking to base
######################################################################## 100.0%
base:e9cb4ad9173245ac
hello world
chooper@chimay:~/projects/docker/bin$ ./docker run -a base echo "hello world"
hello world
chooper@chimay:~/projects/docker/bin$ ./docker run -a nosuchimage echo "hello world"
Downloading from http://s3.amazonaws.com/docker.io/images/nosuchimage
Unpacking to nosuchimage
######################################################################## 100.0%
Error: Error downloading image: nosuchimage
chooper@chimay:~/projects/docker/bin$

[shykes]

Thanks for the contribution!

You can use ioutil.Discard instead of os.Open("/dev/null")

It's in package io/ioutil

[shykes]

Also, how does it behave when you pin the image version?

• If I run 'docker run base:NO_SUCH_ID' does it try running it even if another ID is available?

[chooper]

The run fails because "dotcloud pull" fails:

chooper@chimay:~/projects/docker/bin$ ./docker run -a base:d34db33f echo "hello world"
Downloading from base:d34db33f
Unpacking to base:d34db33f
curl: (6) Couldn't resolve host 'base'
base:d34db33f:e3b0c44298fc1c14
lxc-start: No such file or directory - failed to mount 'proc' on '/usr/lib/x86_64-linux-gnu/lxc//proc'
lxc-start: failed to setup the mount entries for '87926c6f'
lxc-start: failed to setup the container
lxc-start: invalid sequence number 1. expected 2
lxc-start: failed to spawn '87926c6f'

I'll add better error checking for CmdRun and open a separate issue for CmdPull:

chooper@chimay:~/projects/docker/bin$ ./docker pull base:d34db33f
Downloading from base:d34db33f
Unpacking to base:d34db33f
curl: (6) Couldn't resolve host 'base'
base:d34db33f:e3b0c44298fc1c14

[chooper]

Don't merge this pull request yet. I just noticed that rev 8e0986c breaks the progress bar on "docker pull"

[chooper]

This is ready for review

[chooper]

I made those last improvements I wanted to make. I didn't remove "curl" from the requirements in the README because we might be telling people to download installer scripts that way.

[chooper]

Still fighting with unit tests, I'll ping you when this is ready for re-review/merge

[chooper]

Unit tests passing, except for layers_test which appears to be broken in master as well.