Detect backing filesystem for lxc container dir.

Detect backing filesystem for lxc container dir.

Have the LXC container manager know the underlying
filesystem of the container directory.

This is necessary for the container manager to become
btrfs aware, for snapshotting containers on clone.

https://code.launchpad.net/~thumper/juju-core/container-dir-filesystem-type/+merge/210101

Requires: https://code.launchpad.net/~thumper/juju-core/autostart-containers-after-creation/+merge/210099

(do not edit description out of merge proposal)

[thumper, 2014-03-09 21:39:10]

Please take a look.

[axw, 2014-03-10 01:20:01]

https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go
File container/lxc/lxc.go (right):

https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go#newcode49
container/lxc/lxc.go:49: var FsCommandOutput = (*exec.Cmd).CombinedOutput
Do you really want CombinedOutput? Just Output, I think.

https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go#newcode52
container/lxc/lxc.go:52: cmd := exec.Command("df", "--output=fstype",
LxcContainerDir)
If you use Output instead, you can store Stderr in a bytes.Buffer and add it to
the error for context.

[axw, 2014-03-11 04:12:12]

On 2014/03/10 01:20:01, axw wrote:
> https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go
> File container/lxc/lxc.go (right):
> 
> https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go#newcode49
> container/lxc/lxc.go:49: var FsCommandOutput = (*exec.Cmd).CombinedOutput
> Do you really want CombinedOutput? Just Output, I think.
> 
> https://codereview.appspot.com/73310043/diff/1/container/lxc/lxc.go#newcode52
> container/lxc/lxc.go:52: cmd := exec.Command("df", "--output=fstype",
> LxcContainerDir)
> If you use Output instead, you can store Stderr in a bytes.Buffer and add it
to
> the error for context.

After discussion, LGTM, since you won't get mixed stdout/stderr.