cmd/plugins: juju restore plugin

cmd/plugins: juju restore plugin

We also tweak the juju backup plugin so that it preserves
user name and other file metadata.

Verified live.

https://code.launchpad.net/~rogpeppe/juju-core/470-juju-restore/+merge/199711

(do not edit description out of merge proposal)

[rog, 2013-12-19 20:06:26]

Please take a look.

[thumper, 2013-12-19 21:59:02]

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
File cmd/plugins/juju-restore/restore.go (right):

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:82: return nil
Many commands use 'return cmd.CheckEmpty(args[1:])' in this situation to
explicitly error if given too many positional args.

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:87: tar xzf juju-backup.tgz
what if the filename isn't juju-backup.tgz?

[rog, 2013-12-20 00:11:37]

Does this look good to you otherwise?

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
File cmd/plugins/juju-restore/restore.go (right):

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:82: return nil
On 2013/12/19 21:59:03, thumper wrote:
> Many commands use 'return cmd.CheckEmpty(args[1:])' in this situation to
> explicitly error if given too many positional args.

I prefer a better error message.

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:87: tar xzf juju-backup.tgz
On 2013/12/19 21:59:03, thumper wrote:
> what if the filename isn't juju-backup.tgz?

That is what we copy the file to. It would probably be more obvious if this
script was defined closer to its use, below

[thumper, 2013-12-20 01:17:28]

LGTM - although I still think you should be explicit in the handling of unused
positional args.

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
File cmd/plugins/juju-restore/restore.go (right):

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:82: return nil
On 2013/12/20 00:11:37, rog wrote:
> On 2013/12/19 21:59:03, thumper wrote:
> > Many commands use 'return cmd.CheckEmpty(args[1:])' in this situation to
> > explicitly error if given too many positional args.
> 
> I prefer a better error message.

What error message? You don't error out if they give you parameters that you are
not going to use.

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:87: tar xzf juju-backup.tgz
On 2013/12/20 00:11:37, rog wrote:
> On 2013/12/19 21:59:03, thumper wrote:
> > what if the filename isn't juju-backup.tgz?
> 
> That is what we copy the file to. It would probably be more obvious if this
> script was defined closer to its use, below

Ah... I see now

[rog, 2013-12-20 08:48:19]

Please take a look.

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
File cmd/plugins/juju-restore/restore.go (right):

https://codereview.appspot.com/44350043/diff/20001/cmd/plugins/juju-restore/r...
cmd/plugins/juju-restore/restore.go:82: return nil
On 2013/12/20 01:17:28, thumper wrote:
> On 2013/12/20 00:11:37, rog wrote:
> > On 2013/12/19 21:59:03, thumper wrote:
> > > Many commands use 'return cmd.CheckEmpty(args[1:])' in this situation to
> > > explicitly error if given too many positional args.
> > 
> > I prefer a better error message.
> 
> What error message? You don't error out if they give you parameters that you
are
> not going to use.

Ah, sorry, I'd missed that. Done.

[rog, 2013-12-20 15:35:15]

Please take a look.