cmd/juju: add juju set subcommand

cmd/juju: add juju set subcommand

This proposal only includes the command parsing, a following CL 
will include --config parsing and config updating.

https://code.launchpad.net/~dave-cheney/juju-core/094-cmd-juju-config-set/+merge/124105

Requires: https://code.launchpad.net/~dave-cheney/juju-core/094-cmd-juju-config-get/+merge/124094

(do not edit description out of merge proposal)

[dave_cheney.net, 2012-09-13 07:24:17]

Please take a look.

[fwereade, 2012-09-13 10:42:53]

A few questions and minors...

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go
File cmd/juju/set.go (right):

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode33
cmd/juju/set.go:33: }
if c.ConfPath != "" {
    panic("not implemented")
}

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode35
cmd/juju/set.go:35: if len(args) == 0 || len(strings.Split(args[0], "=")) > 1 {
Just a thought, out of scope -- should we perhaps be reusing the get/set
commands for env-get/env-set when no service name is specified?

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode56
cmd/juju/set.go:56: return nil, errors.New("missing option value")
Why can't we set values to empty?

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode59
cmd/juju/set.go:59: }
hmm, should we error out when nothing is actually set?

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode70
cmd/juju/set.go:70: return nil
panic("not implemented")

[dave_cheney.net, 2012-09-13 11:48:03]

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go
File cmd/juju/set.go (right):

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode33
cmd/juju/set.go:33: }
On 2012/09/13 10:42:54, fwereade wrote:
> if c.ConfPath != "" {
>     panic("not implemented")
> }

Done.

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode35
cmd/juju/set.go:35: if len(args) == 0 || len(strings.Split(args[0], "=")) > 1 {
On 2012/09/13 10:42:54, fwereade wrote:
> Just a thought, out of scope -- should we perhaps be reusing the get/set
> commands for env-get/env-set when no service name is specified?

SGTM

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode56
cmd/juju/set.go:56: return nil, errors.New("missing option value")
On 2012/09/13 10:42:54, fwereade wrote:
> Why can't we set values to empty?

Yes, this should be possible, but there might be some slight of hand with the
zero value required for options that are no string types. Ie, 

key="somebooleanvalue"
value=""

^ coercing "" to a bool will need some rumination.

https://codereview.appspot.com/6494131/diff/2001/cmd/juju/set.go#newcode59
cmd/juju/set.go:59: }
On 2012/09/13 10:42:54, fwereade wrote:
> hmm, should we error out when nothing is actually set?

Maybe, this is just the scafold at the moment.

[fwereade, 2012-09-14 06:19:16]

LGTM on the understanding that followups are coming. We should try to talk with
niemeyer about clearing settings; I think there's some potential interaction
with the current "incompatible charm upgrades" thread on the juju-dev list.

[dave_cheney.net, 2012-09-18 10:09:33]

Please take a look.

[dave_cheney.net, 2012-09-18 10:12:07]

*** Submitted:

cmd/juju: add juju set subcommand

This proposal only includes the command parsing, a following CL 
will include --config parsing and config updating.

R=fwereade
CC=
https://codereview.appspot.com/6494131